How to Choose the Right Size Carburetor
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- เผยแพร่เมื่อ 25 ธ.ค. 2024
- Want to know how to select the right size carburetor? Is it some magic formula or do you need an old guy to choose what's right for you? How many CFM do you need? Should you go bigger? Lets go through it and find out the best way to choose one.
AVS2 650 - amzn.to/3b7kP8S
AVS2 650 w/man choke - amzn.to/2JEcqOU
AVS2 800 - amzn.to/350F1Wf
AVS2 800 w/man choke - amzn.to/2XcAgnX
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Holley 600 w/vac sec - amzn.to/3b8kP8D
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Holley 750 w/vac sec - amzn.to/38XDXU1
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#edelbrock #holley #carburetor
Thank you for such an informative video!
I’ve been telling guys since the early 80’s that you have to spec your components for what you want out of it.
They always said bigger is always bigger and you have to chrome it, etc.
I’ve grown up trucking in my blood with the family business. Every truck is different and has to be spec’s out for different applications. If you spec it wrong, it will not be able to do what it was intended for and you can’t make money from it. It will end up costing you more money just to operate if at all.
You explained it very well. You have to first figure out what you want out of it and go from there.
That is why so many guys go and buy that dream car and end up crashing it moments after picking it up. You have to know what the vehicle is capable of doing and what you are capable of doing also. Once you get all the parts of the equation down, you will have a near perfect machine!
I say near perfect because we are never satisfied once you start down this road. lol!
Thanks!
Thank you! You bring up lots of good points. I like to take as much guess work out of things. If you can at least have a process, you can anticipate the results.
Even before seeing this, I believe most guys have too much carburetor on their engine. 750 cfm seems to be the default carb everyone uses, but I chose a 600 cfm for my bone stock 396 325 hp big block. The street manners and throttle response are impressive, better than any of my injected engines in fact. I've had many guys tell me I need a 750, that a 600 is too small etc. but nope.
Really all depends on what you use it for and what it’s set up for. I worked on a set up this morning that was WAY over carburated. I offered to tune one of mine on his set up to prove it. It really common and like you mentioned, doing it right will get you a better running engine. Thanks for watching!
Interesting, anybody's 350 cid V8 at 5000 rpms only needs around 375 cfm, maybe 400 cfm at 5000 rpms, and most street cars never go to a higher rpm than this. Yet most guys never go lower than 650 on a carb, and many go to 750. We need to be realistic when we enter data as to what the revs are going to top out at.
@@bobkonradi1027 and the factory carb was a 750.
The factory carb was a 750 Q-jet, the 350 hp 396 had a 750 holley carb.
True. It’s easier to pick one carburetor and put it on everything than to switch it up. Doesn’t mean the engine is using all 750 cfm. They put 750’s on 305’s and the secondaries wouldn’t even open all the way even at 5500 rpm.
When towing or using engine in a heavy vehicle go smaller CFM. Air Velocity is what we are after in carburetor sizing. We want high air velocity so the carburetor works properly plus to fill the cylinders well especially at low rpms. If air velocity falls off due to carburetor being to big low end suffers. That's why smaller for towing and heavy vehicles. You can go bigger with lighter vehicles and higher rpms engines. When driving on the street we don't see much past 3500 rpms so the high air velocity of a smaller carburetor provides a much better driving experience. Good stuff!
Quality comment, thank you Cliff !
Few weeks ago Brian helped me work through picking the proper fuel delivery for a project I'm working on; very nice and knowledgeable guy. Thanks again Brian.
Best of luck with your project!
I just let your video audio Play in the shop when I’m working and not in the mood for music. It’s great background noise that also refreshes knowledge
Nice! That’s pretty cool actually. 😆 I’ve always wanted to be background noise! Thanks for the laugh. I really do appreciate that and glad you found a way to listen. It’s a great idea! I might start doing the same.
Just ran across this video. It was VERY informative. Here is my dilemma: I have a stock 350 sbc in a 72 Impala coupe (weighs about 3900 lbs.) with a 200R4 transmission and 3.73 rear end. An Edelbrock 1406 (600 cfm) sits atop a dual plane intake manifold that is fed by in-tank pump (max psi: 49-50) regulated to 5.5 psi by an AER fuel regulator. Max RPM for the engine is 5500; however, I have yet to hit 4000 even on the hills in my locale (3800 was the highest so far). I do not race but use the 3.73 gears for acceleration and the 200's OD to cruise. The 1406, IMO, burns too much gas. Edelbrock recommends the 1406; however, an older mechanic I know suggested moving to the 1404 (500 cfm). The math in your video also supports that mechanic. I'm looking for a final confirmation prior to spending the money for a new carb.
If you’re only spinning it to 4000 rpm, then that’s your number. Make the switch to a 500 and then TUNE it for your application. It’s not correct right out of the box. Never is. Once it’s tuned, then you can determine if it was the right move. Sounds like it will be.
@@MuscleCarSolutions thanks for the IMMEDIATE response 👍
@@ernestadamsjr.2662 sure thing. Best of luck with it! My family had a 72 Impala sedan when I was a kid. Love those cars!
If anybody is wondering the 3456 comes from converting cubic inches to cubic feet and from considering that the car is 4 stroke meaning you will only pull air every other rotation.
Then it means you need to half these numbers when using a 2-stroke carb. Or am I wrong?
I did wonder, ty.
Man iv follow you. I got a 350. 1972 Monte. It's a cruiser. But she likes to go fast. I put the fuel just like you I'm sitting at 5000 in Colorado. Adjustments made according to the chart. Still runs rich rich
I just had an "Ah-ha!" moment at @16:10 . It took me a couple runs through your other good videos. U never know what you missed when you don't understand stuff. Thank you, again!
Nice! Well I hope you got the answer you were looking for! If not, just ask and we’ll figure it out. ;)
@@MuscleCarSolutions Thanks! Yeah. I'm trying to piece how it all works. Fun to learn. 👍 I'll have more ?s down the road...har har...
@@stuckinmygarage6220 all good! I’ll be here!
I had a '77 Camaro back in the mid to late 80's that had a .40 over 350 with flat top pistons, roller rockers, stock exhaust manifolds a TH-350 trans, stock converter with 3:08 rear gears and 305 two barrel heads with small ports and an RV type camshaft ( I don't remember the brand name or specs on it though) that had an almost stock idle but you could tell it wasn't completely stock, the intake was a dual plane Edelbrock performer and I put on a 600 Holley with vacuum secondaries. I dont remember if the Edelbrock carburetors were around yet but the Holley was just over $100 brand new back then. I never had to fool with the jets or anything other than the idle speed and mixture, it ran pretty well out of the box. I ended up daily driving that car for quite some time. I had to watch the fuel quality and timing since the 305 heads bumped up the compression a bit but it had excellent throttle response and averaged around 17 MPG on the highway. I'm sure the cam, heads and exhaust held back any real top end performance but the low end torque was good enough for what I used the car for since it rarely saw anything over 4-5K RPM. I still regret selling it along with the other old cars I used to have which were cheap and plentiful back then.
Hi there so I have a 78 bronco with a 460 out of a 70s motorhome. Can’t get it to run fast and efficient lol what carb do you recommend. Currently has a 750 with Edelbrock dual plane manifold
Not sure I understand what you mean by fast and efficient. What is it doing that you don’t like and how have you attempted to tune it? What size did you come up with after watching the video?
I'm running a junkyard low compression dodge 360 , edelbrock 340 manifold , A body manifolds true dual in a 3300 lb car and 373 diff with a edelbrock 600 cfm , mostly in town driving . Runs great , amazing fuel mileage and spark plugs are a light brown .
I have chevy small block what size is best for saving fuel?
Q-jets use the airdoor to tune the cfm.Everyone of them has at least the 750cfm potential i.e. of some rare buicktypes. The factory used the angle of the airdoor for setting the carbs to tamer or smaller engines
Correct but my understanding and experience with them since I was a young man..2 types 750 and a 800 CFM..Look down the secondary if thier is a nub sticking out.. It's a 800 CFM...looks like the tip of your pinky finger..Other wise smooth it's a 750
thanks for clearing alot of this up, I have been looking for a Holley DP for my 466 BBF in my 78 f100 street/strip truck (mostly street realistically), have been concerned about going to little or wasting time over carbureting
It’s a common mistake. It’s easy to say go way bigger and think it’s better than finding what the need of the engine is.
Lol, here I am again listening to your videos. Just put all the side markers in my Mach 1. A tie rod end. And adjusted my reverse band all while listening to these
Appreciate that! Hopefully there was something in there you found useful. 69 or 70 Mach 1 is a bucket list car for me. One of these days!
First - Thanks so much for all your Wonderful Video's. I've never been very well versed in Cars/Working on them. But have just acquired a new care "to me" and have been trying to learn about Carbs and
how they work and how to work on them and your video make thing very clear and understandable even for a 71 yr old Rookie ;-)
So, I have a 1990 Chevy 383 Stroker Motor, in a lightweight car (2700lbs) not sure of any of the internals with the exception Of
it came with documents for an Isky Mega 280 Cam, and it has an Edelbrock 1405 that has had an
Electric Choke added at some point. I did check the Metering Rods and they are the .070 x.047. I've been learning about the timing and have 18 deg Adv and 34 in at about 2500rpm. Hope this is enough information to be able to make some suggestions.
Thanks again, Take Care,
CK
Glad you’re enjoying the videos! So the root question here is the 600 the right carb for the 383 in a light car. First things first. We have to ask the question, “what are you doing with the car”? Just a fun cruiser or something more aggressive? I don’t know a thing about the specs on that cam but I’ll assume they’re around 230 and a fairly tight LSA. 107? That cam is likely going to be done by 6500, so now we know what the max rpm is. The rest is simple from the video. On a lighter car, a little more CFM isn’t a bad thing. If you’re going to work in the power band of that cam (if my assumptions were correct) then a 750 would be a great carb for that set up. Just have to make sure the rest of the engine combination match and you’ll have a screamer of an engine!
Hi,
Thanks so much for the reply and information. I'm just going to be cruising around in it on Nice Sunny Days. I think all in at 6500 is probably all my Heart can take ;-) Appreciate everything, Take Care,
CK
@@CKirk2727 I just found that cam. It’s not going to be a lot of fun for a cruiser. It will sound good, but it’s going to be down on power below 2500. Not very fun. I’m assuming that’s what you’re after though. In which case, the 600 might be ok.
Hi, LOL I had that feeling even with the short amount of time I've had it and driven it.
BUT It is what it is, at least now I know and so that will make things a lot clearer on it's performance, and drivability, and makes me feel a little better about my driving and tuning attempts. Thanks so much again for all your Help and the Great Video's I've learned a lot !!!
I got an 350 small block hard to find a carburetor here I need a lil help
@@xpirxtion same here.
@@ricardssamuls9152 what's the application?
Thanks for mentioning the dump truck engine. I’m I’m the beginning stage of planning a rebuild of a Ford 460 for a stake body that it’s sole purpose is to haul firewood.
Not much information about building high torque low RPM work engines.
Yup. Every year I get quite a few low rpm, high torque applications to help select components for. Dump trucks, yard dogs, logging trucks. Lots of gas powered stuff out there. Surprising how small a carb will work for a 460 when you’re only turning it less than 4000 rpm. Good stuff! Thanks for stopping by!
Thank you for the knowledge but I wanted to ask to be sure I have a 1978 Ford F250 super cab 4x4 with a 460 4000 rpm would probably be my max rpm I'm looking for fuel efficiency more than anything daily driver if you could help me pick a cfm that would be great I run maybe 85 or 87 from the gas pump
Well, you have the key components there. What did the math tell you? Something to keep in mind here. If you really want better fuel economy, and this is something you’re driving frequently, you’ll find those big gains in the transmission, not the engine. I did a video on how to get better fuel economy in a muscle car a few years ago to illustrate how that’s possible.
@@MuscleCarSolutions sounds good I'll find the video I have a C6 automatic transmission if that helps
I have a 350 chevy in an 1981 Chevy k10. I installed a new crate engine in it to replace a worn out 305. I used an Edelbrock AVS2 650 with electric choke. I have the initial timing set a 10 degrees BTDC. The issue that I am having is that when it is warm out and I turn it off, it is hard to restart and acts like it is flooded on restart after 20-30 minutes. I have not made any changes to the carb at this point. I put hedman hedders and glass pack mufflers on it when I installed the engine 3 years ago. So there is no catalyst now. OE fuel pump, no regulator. I'm wondering if the fuel pressure is coming up with a hot engine and leaking past the needle and seat. I have a thermal shield on the fuel line from the fuel pump to the intake manifold, Edelbrock thermal mounting gasket and the adapter to mount a carb. to a quadrajet manifold also. Thanks for any advice that you can give.
It sounds like the thermal gasket isn’t enough. Should have plenty of room under hood to run a thicker spacer. I did a video on heat soak and ways to help cure it. What you’re experiencing is common with the crappy ethanol and fuel we have today.
70 chevelle 10:1 383 230-240 , advertised 280-290 duration, 489 int lift, 519 exhaust, rpm air gap intake, header and full 3' exhaust, th350 2500 stall and 3:42 gears.
I have a '67 Dodge charger, 360cid (sheet metal kits/better camshaft) I put an edelbrock CFM: 600 on it with an electric choke, it worked really well, then the electric choke broke, I didn't know you could buy a repair kit. I bought a new edelbrock 600, manual throttle, I've never gotten it to work well, the nozzles have been changed and sometimes too much petrol or too little, when I'm sitting in a wheelchair, I can't install it myself anymore, Finland has good installers for sure, but they're too expensive for someone on a small pension , would it be a replacement, for example, a holley double pump??
Don’t blindly change parts. Figure out the resin for the issues and fix it. Just mindlessly swapping parts/carburetors isn’t going to solve your problem. Finding the problem is a whole lot less money than the expense of buying an expensive new carburetor every time. I’ve got videos on all the issues you mentioned.
@@MuscleCarSolutions is the edelbrock 600 the right size?
@@petskudahlman I don’t know. You didn’t provide enough info to make that statement. You watched the video? Based on what was in it, what CFM did you come up with?
I have a 1978 c3 corvette L-82 silver anniversary edition. I would like to upgrade the carburetor. What size cfm carb would I need and if I upgrade the air intake manifold am I able to choose any one? Ideally I would like to go fuel injected but I am not sure if I have to add an ecu or not.
Also, it is a manual transmission
@@FrankPung the trouble corvette owners universally experience is lack of under hood space. The only manifold that Edelbrock offers that will fit under that hood is the Torker and honestly, it’s not a very good intake. It is low profile however but it’s a low end power stealer. Lots of folks use them, but be prepared to lose some 2500 rpm and lower power. Yes, all aftermarket fuel injection systems have a computer to control the fuel and spark. They’re not very complicated, but you need a good installer that’s competent in that type of work or time on your own to learn how to get them set up right and how to correct any issues the system may experience.
I have a 84 Silverado 3/4 ton truck with a 350 motor. Truck will be used for towing/hauling and weekend driving. It had an edlebrock carb when I got the truck but I want to upgrade it. Holley 600 or 650? What do you recommend?
If towing and hauling are your plans, the Edelbrock is a better choice. Holleys works exceptionally well in WOT and racing situations.
Putting together a 289 Ford engine in a tiny 2500 lb Sunbeam Tiger. Small 270 cam, dual plane intake, stock exhaust manifolds, 4 speed manual. Will be driven conservatively with the occasional spirited sprint down the on ramp, maybe 5500rpm max. Math works out to 459 cfm. I'm thinking about a 500 cfm 4 barrel...what do you think? Do you know if Holley makes a 500 cfm carb? Or would Edelbrock be a better choice in this case
In this case with a lighter car, I’d use a slightly larger carburetor. 600-650 would be just fine. Everything you have mentioned would match up well with that. Part of the issue with these formulas, they aren’t an exact science. 👊
@@MuscleCarSolutions Thanks! Do you have a personal preference between Holley and Edelbrock?
@@StLouisSled all depends on what you’re going to do with the car. Drag race only? Holley. Street driving? Edelbrock. For what you explained, I’d lean towards the Edelbrock. Easy to tune and will be very friendly for what you’re doing with it.
500 to 550 sounds fine. My friend used a 600 vacuum secondary carb on his 65 Mustang with a 289. Keep in mind two thing. A manual transmission can help a car with too much CFM. When I was in HS, we built a 10.90 comp car at the winter nationals at the old track just outside of Phoenix, Beeline Dragway. We ran a 283 bored out to 292 cubic inch engine. It had a solid roller cam and a 1050 dominator. Again, running a manual trans would have helped, but this high winding screamer was backed by a 2 speed powerglide automatic. It took a good tuner to get that combination running well. We ran under the index in the final, losing a 10.89 pass to the other guys 10.94. Kind a hurts when you lose because you went too fast!
@kennethcohagen3539 I remember beeline in the 70s. Left PHX 20 years ago. Would run out there as an adult just to remember my youth
425 cadillac bored .600 due to cylinder wall damage, so 439 Cid. Stock cam. Dropped into a 64 Buick LeSaber with 3.42 rear gears. Max rpm before valve float is 4500 rpm. Torque peak is 2000, horsepower peak is 4200. I honestly thought the car had had higher rear gearing, but it was originally a manual car with a 300 Cid v8. They all got deeper rear gears. 2000 rpm is 50 mph. Top speed is 107 before valve float shuts it down. Car is primarily a weekend cruiser. I have a 750 cfm Edelbrock on it. Original carb was a 800 cfm Quadrajet.
The Qjet can be a little deceiving when you just look at the CFM number. Yes it capable of 800 CFM but I’d you look at the primaries, they are in fact substantially smaller than the secondaries. It’s how GM wanted to control the fuel and give the air and fuel needed when the demand was needed. The difference in the two carbs really can’t be compared on CFM alone. But you certainly have a lot of cubic inches to feed if you decide to go bigger on that cam! Awesome to hear you’re running a big Caddy. Always fun to see those big old school engines still on the road!
@@MuscleCarSolutions Thanks for the reply. I got the Caddy and TH400 behind it pretty cheap and went with it. It's been fun, but frustrating at times. Partly because I chose a car that isn't common, and an engine to swap that isn't common, either. I'm considering upgrading to a mild cam and stronger valve springs to go to 5000 rpm.
@@johnbutler1323 that’s the downside of the cool factor. Fewer things available for their engines that don’t have a lot of volume to support lots of aftermarket parts. Which just makes what you’re doing even cooler!
@@MuscleCarSolutions Thanks. One of the crazy things about the 425 Caddy is they debored the big 472 from 4.3" to 4.082" and kept the same 4.06" stroke. When they did, they knocked off every ounce of excess metal in the block and heads and actually opened up the water jackets quite a bit. The 425 Caddy big block weighs 100 lbs less than the 472 it's based on, putting at 525 lbs, which is 50 lbs lighter than a fully dressed Chevy small block with iron heads and intake and comes out about even when the Chevy small block has aluminum heads and intake. It's a very light engine for its displacement, especially considering it's all iron. The block is so light, I could pick it up and carry it around when it was stripped. It does take up a lot of real estate, though, and is every bit as wide as a Ford mod motor.
Great video what whil you choose for a 1957 cadillac coupe deville whit a 365 enginge the 500avs2 or the 650 avs2 carb
Based on the information in the video, what did you come up with? If you watched it, you know that there’s not enough information given to make a recommendation.
@@MuscleCarSolutions the car is full origenal but my carb is bad en want to replace it
@@jantienesstruyk3538 understood. I still need all the info from the video. Like max rpm?
@@MuscleCarSolutions the car make max hp at 4800 rpm 320 hp thats al i now i just bouth the car ful stock only want to change the carb en go whit a electronic ignition
@@jantienesstruyk3538 ok. So now you have the CI and the RPM and you can make a choice. Seems like a pretty easy decision. The 500 would be the best way to go.
Great video, alot of guys over cam & over carb their street engines......I am building a 350 Vortec and I picked up a used 600cfm Edelbrock Performer(gonna do a rebuild on it just to be safe). This entire engine is being designed around that 0-5,000 rpm street tourque band. Scored a dualplane non airgap intake. If/when I change the cam I am going for a tight LSA (probobly 108) with a 0-5,000 appropriate duration etc. I am all about that throttle response since I am gonna spend waaaaay more time at 3,000 rpm vs 6,000rpm.....heck I am gonna roll manifolds since headers are a nightmare. Hp/cu-in in a light weight 2wd GMC Jimmy is gonna be FUN.
Great video!! my application is a little different 350ci only turning 3000 MAX rpm on a airboat by your calculations a 500 cfm holly is more than enough. my question is i hear they make a 480 cfm holly 4 barrel would that be a better fit than the 500 2 barrel? Thank you in advance .
Hi, love the content, I've got a 383 Chrysler stroked to 489, mild hyd roller cam and alloy heads, Thinking 750cc will be enough for street, auto 4 sp and 5500 max revs ?, thanks
@@adampell1607 that’s probably where I’d start but knowing the cam specs and being honest about how you want to drive it are the some big factors.
Awesome, yep street car 99 of time. Cheers for the help👌@@MuscleCarSolutions
@ then it will be a very easy size to tune for that application. 👍
I have a 1967 chevy 327 that is stock to mildly built I really dont any other specs....what would be a good size/brand of carb to go with?
You’re in a very difficult spot then. The only way you have left if to define how you’re going to drive it and define what your max rpm is. Then it’s a matter of living with your choice and tuning for that situation.
@@MuscleCarSolutions It's gonna be street driven, weekends and some daily driving,350 turbo trans basic little truck
Well that’s the driving part. Now make a decision on what the max rpm will be and you’re in your way to picking a CFM for that situation.
Great video by the way very informative for people such as myself.
My truck has a 700r4 tranny and the axel gear ratio is unknown at the moment.
Looking for some help. My 86 camaro came with a stock 305 carbureted. The Qjet carb it came with is listed as 750cfm. I bought a 750 cfm edelbrock but everyone is telling me it's to big. Why would it not work if it is the exact same cfm as the factory Qjet. Thanks for any feedback.
Because they deliver fuel differently. Stock 305 is better with a 500cfm Edelbrock.
Great video. I’m new to this and I’m hoping you can give me some guidance. I recently bought a ‘70 c10 that has a sbc 400 with a th350 trans & a 373 rear gear. As far as I can tell the motor is stock. According to some forums I read my trans should shift at around 4500 at wot. When I do the calculations I come up with 520cfm without using the Volumetric efficiency. I’m looking at an edelbrock AVS2 carb in either 500 or 650 cfm. Would you go with the 500cfm if you were just using the truck as a cruiser for the most part?
Because of the cubic inches, I’d probably opt for the 650. Especially with that rear gear. But the biggest question would be, are you planning on any upgrades in the future? Headers, intake, better ignition, etc. if the answer is yes to any or all of them, go with the 650.
Not planning any engine upgrades. There are lots of other things that need attention. I can’t say for sure if I will do some in the future or not. That being said do you still think the 650 is the way to go? When it comes down to it I guess what I am wondering is how much the throttle response will suffer with the 650 if no changes are made to the motor.
Love the video I have a 462 Chevrolet with Pro race right heads elder aluminum 850 cam max rpm 6500 my spark plugs go bad very quickly. Is this carbureted working properly Is it big thank you
I have a 68 f100 long bed . Has a 390 bored .040 mild cam, headers aluminum dual plane intake, and exhaust. automatic transmission. Stock gear ratio. Just a street cruiser. Probably never see 5500 rpm. What are your recommendations.
@@Mjmarquez1984 what did you come up with based on the information in the video?
It came out to a 600 cfm if I round to the nearest hundred
@@Mjmarquez1984 sounds reasonable to me if 5500 is your limit and it’s just a cruiser. Will be very easy to tune.
400 small block bored 30 over with small cam. Got a 750 cfm and a 600 cfm amdni camt seem to get either one adjusted to get the stumble out when the throttle is hammered down
Well. Start with the CFM. Which best fits your situation based on what the video showed? Next if verify initial and full timing. Then verify proper fuel system set up. Then you can start tuning.
I ran your equation on a ZZ4 Chevy motor , 350 x5800 /3456 = 586.3 CFM carb. Chevy documents for the carb calls out for 750 CFM Holley. I have a 600 CFM double pump Holley carb. I am assuming the 750 must be jetted down and my 600 jetted up. Kinda confusing.
You cant tune CFM. It’s a fixed number. You can however adjust fuel and spark to help tune the engine to its full potential. Are you using this as a drag only engine? Any other upgrades of significance? Nitrous? Boost? Then maybe... and that’s a big maybe, a 750 would work. Only if it were a vacuum secondaries carb. Like what was mentioned at the end of the video in other details to look at to confirm the right size. What are you using the engine/car for?
No it’s not a drag vehicle, I have a 1965 El Camino . It’s just a street Rod. I have an appointment with RPM carburetor shop to get it tuned, but I watched your video and ran your numbers for curiousty. Chevy 750 carburetor was most likely for drag car. Thanks
Well a street car is a whole different story. How often do you see 5800? If you’re just cruising, not often at all. You may see it if you’re doing some more aggressive driving, but unless that’s a common occurrence, you’ll never use the CFM that carb delivers. With a 750 it’s going to be very rich pretty consistently. There are a number of other things to consider but in very general terms, it’s all about assessing how you’ll drive it and those factors that are unique to your situation.
@@MuscleCarSolutions I have a ZZ4 in a 29 model A that I just got. It has a 750 on it now but leaking and I was going to replace it. The motor has a performer RPM manifold and edelbrock mechanical fuel pump.Was told it was a stroker motor. But I'm not sure. I was wondering if you think a Edelbrock 600 or the AVS2 650 would be best? Just a cruiser hot rod. Just trying to get it running right to enjoy.
Hello from Canada!
I recently picked up a 1977 GMC Sierra K15 4x4. It's 98% complete. The previous owner dropped in a late model gen1 350 TBI and running gear from a 1987 Chevy Suburban. It's not running it was just placed in, nothing hooked up.
I would like to swap out the TBI set up and put an aftermarket dual plane intake and carburetor on it, possibly headers I can't find any cam specs on this engine but do know it makes 200hp and 300 ft/lbs, At what rpm I don't know.
Realistically this engine wont be seeing to much time at high rpm, probably 5500 max. I keep doing my calculations with a 350 ci and 85% VE and the number keeps coming up at or around 470 cfmchevy. This seems way small for a small block Chevy.
It's a truck build and I'm looking at getting the Holley 90470 off-road carburetor. The website says recommended for 4cyl, v6 and inline 6 engines. Is this carb a poor choice or just what I'm looking for. The next size up in this series is a 670 cfm.
Im in Canada and these carbs are going for just over $1000, I gotta get this right the first time.
Your opinion and knowledge means a lot to me right now, thanks
The thing is if you’re not sure on the cam profile or you feel like a 500 CFM carb would be too small, then put on a bigger one. I can tell you at that Hp level and likely won’t spin that thing past 5000 rpm, I’d have no problem putting a 500 on. But like I said above, if a larger size will make you feel better, then go for it. You’ll know if it was the right choice or not if the tuning becomes difficult.
Was wondering what you think of a 750 Holly 4 barrel on a 428 cobra jet Torino, with air ram, 1969 fastback
For the same reasons in the video, I can’t answer that question without a bit more info.
Looks like the secondary plates are same size as primary . I want to use an Edelbrock on a 460 cid but all I have seen is models that have slightly larger secondary plater . What is model # of carb. in video ?
The 750s and 800s have the same size primary and secondary bore sizes. More importantly, the venturi sizes are different in all CFM sizes.
Hi 454 Chevy 100 octane fuel in a Vdrive boat 6000 to 6500 RPM roller cam what do you suggest for Carb. thanks
I have a 360 Chevy big camera 202016 exhaust for tens in the rear 4 speed to Chevy Malibu 78 I'm going to ask for a size cop should I put on it
I have a 400 sbc with dart iron eagle heads 2.0. ,xe 274-10 cam . I have a 750 dp quick fuel brawler.
is this too much carb? you have been a godsent to me so far. thanks 70 primary, 80 sec 6.5 power valve. has a miss when secondaried come on.
That’s a a really good cam. 230/236 on a 110. Installed a ton of them. It’s all in by 6000 though but if you’re going to the track on occasion or aggressive driving, the 750 should be just about right.
I have initial timing set at 8 and total at 35. my manifold vacuum is only showing 14 hg inches at idle of 800 rpm. msd ready to run diz with va.
I been chasing a bad stumble when you smash the throttle, bogs, spits sometimes backfires. I can ease into throttle up to 100mph but when I go wot it falls. muncie m20 4 speed. 69 Beaumont (Canadian chevelle). 3400 lbs. Could the 6.5 pv be too small or blown perhaps from all the backfiring? Appreciate any help.@@MuscleCarSolutions
@flyinhighaerial3193 couple things jump out here. 8° is not a lot of initial timing. I’m down close to sea level and start at 12-14. If you’re in Canada, I know you have some different fuel options so even if you’re running a fuel with no ethanol, add a bit more timing. Backfiring. The newer carbs have the check ball to keep the PV from being blown out every 2 minutes but it wouldn’t hurt to change it. I’d you’re seeing a stumble, you can try two things. Make sure you have the accelerator pump arm adjusted correctly and you can change the PV. If you want it to come in later and you’ve got the 6.5 in now, change it to a 5.5 and see if it gets better. Worse? Then it could be a lean condition. So go back up with the PV and try again.
Accelerator pump is adjusted. I did drive it for 5 miles to get home and it backfired plenty when I had a coil go bad a couple weeks ago. After seeing your vid on pv’s today I thought it may be the issue.
Today after warming up to operating temp I closed the choke by hand to check for a vacuum leak and could close it entirely with no change in motor. Would that indicate my pv is blown?
Hey your video are awesome,
I’m learning every time.
I just got a 1968 Chevelle with a 307 a 1406 and performer serie manifold intake is it too much?
Runs nice at high rpm if I got stuck in traffic eddy gets flooded….I think
@@dylansretreat could be too much. Really depends on the things I mentioned in this video. Tell me about the 307. Is it stock?
4 scenarios.
1. 70 Torino wagon 351 Cleveland 4v. auto with 3.00 gears. All is stock. It has an EB AVS 650.
2. 71 Torino GT 351 Cleveland 4v. Auto with 3.00 gears. All is stock. It has an EB 600.
3. 71 Mustang Fastback 351 Cleveland 4v. 4 speed 3.25 gears. It has headers EB Performer intake 750 Holley Dbl Pumper. MSD distributor.
4. 73 Australian Falcon 71 351 Cleveland 2v heads auto with 3.00 posi gears. It has a Holley 600 with Edelbrock Performer.
I have tri y headers to put on in the near future.
Can I use a 780 Holley or 800 EB AVS on any of these in the above configurations? Do the 4v Cleveland heads come into play? Would 4v Big heads do better with a 650 at low rpms?
Thank you.
Really you have to follow the formula in the video. Need to know your max rpm and go vehicle by vehicle and make the determination on the best size to go with.
Each would be street driven. Mostly looking for low to mid range torque. Occasionally might see 5000 rpms, but rarely
@@kennethmarston8687 so pretty easy then if you follow the basic formula in the video. If you’re staying under 5000 rpm and mostly stock engines, go with the closest number to what you came up with.
@@kennethmarston8687 I think you’ll find you’re way over carburated on some of those applications.
I have an old step van that I just replaced the Chevy 350 in. Already has an Edelbrock 1406 in and seems to run rich. At 5000 feet of elevation. Can I tune this carb properly for my application?
Thanks!
Can that size be tuned on that engine? Maybe. What did you come up with after watching the video?
Thx for the vid!
Do you think a stock 351 Windsor 2 barrel will benefit from the "big" Autolite 2100 from a 2 barrel 390?
It's one venturi size above the stock carb.
Stock cam street driven, FMX auto.
It ist more about fiddeling around and finding the sweet spot set up for the car.
First of all thank you so much for superb information regarding carburation. You have put my understanding of carburation to another level. Thanks again. I have aquestion for you thats puzzle me alot. I Have a '70 Cadillac Deville, stock engine (375 hp), stock TH400 and stock 2.94:1 rearend. Never passes, and never will, 5000 rpm. When the QJet came to age i put on a Holley 4160 600 cfm (0-80457s). I have a O2 sensor in my exhaust so i can check AFR. What puzzle me is that when passed idle i have almost perfect 14,7:1 AFR. But.... at idle, whatever i adjust or fiddle around with, it never go past 12.0:1. So my idle is a little rough and smell rich. Is there anything i am missing out when adjusting idle or do you have any idea why my AFR are so low in idle?
Hey so I'm young and im learning carbs as much as i can. I have a stock 351w in a 1978 Thunderbird with 2.73 rear gears. Im running true dual exhaust, dual plane intake topped off with a 1405 carburetor running the "10" tune on the 1405 scale. Max rpm 4500. Would a 1404 suit my application better? Or is the 1405 ok?
@@maxsinger3526 depends really. Will always just be a cruiser or do you have plans to build something with more power and rpm? If you’re staying stock and your max rpm is 4500 and it’s just a cruiser, the 500 will be much easier to tune and be a much nicer driving engine.
Just purchased 66 gmc believe it had stock motor and carb 305 v6 and strombreg 2 barrel wondering where I’d be able to buy a remanufactured carb possibly or how to figure out what aftermarket carb would fit on it just for daily driving
Last time I looked there wasn’t a heck of a lot available for those engines. They’re for sure different, but I’m not sure how easy it’s going to be if you want to upgrade anything. I’d have a builder go through the factory carb and leave it be. Unless you plan on swapping the engine to something a little more modern. Then all options are available.
Interesting: The Holley website has a formula and also a little electronic tool where the data is entered and then you get an answer as to what size carb to use. Edelbrock has the same thing. HOWEVER Holley then says to take the cfm recommendation and add 15% to it, for whatever reason. Edelbrock doesn't say this. They just stick to the initial number that their little electronic tool spits out. Both websites do agree, though, on the fact that you have to be realistic in what rpms you're actually going to run the engine at. Don't tell the calculator that you're going to run to 6000 rpm (or whatever) and then actually you never go over 5000.
I'm guessing the 750cfm carb on my 305 low compression el camino is slightly oversized.
It's a qjet the PO put on to replace the feedback carb it came with.
Probably way way too big.
I have a '69 Plymouth Road Runner, 383 HP (with factory mild lumpy cam), automatic and factory a/c. Looking for proper street use Edelbrock AVS2 carb cfm, metering rod and secondary jet size? It currently has an Edelbrock AVS2 1906 (650cfm) that blows a significant amount of black fuel smoke at full throttle. Metering rods and secondary jets were stepped down 2 sizes below factory, as suggested by an Edelbrock technician. Any suggestions?
Adjust the AVS. What is your idle vacuum and what step up spring did you put in?
I have a bone stock sbc 350 with a Holley 650 double pump. Is that too much carb for that motor?
@@jeremywashington-patton9965 probably. Need more details on what you’re doing with the engine/vehicle.
So I’m building a 1996 Chevy Silverado 1500 it’s got the vortec 350 in it and I’m wanting to use it for street and possibly the track and I’m wanting to put a high rise intake on it so what I’m wondering is a 650 too much or not enough for the carburetor I’m wanting to run
What calculation did you come up with after watching the video?
@@MuscleCarSolutions so I used both of them but the first formula I did 350x6000 then divided by 3456 and got 607
Sounds reasonable. I’d you’re primarily going to use it on the street, I’d match that up with your cam selection. Open plenum intakes and very heavy vehicles are generally a dog until 2500+ rpm.
@@MuscleCarSolutions so with cam selections how do you find out the best cam for the build also I apologize this is my first ever build and I’m new to all of it
@@Smokingjoe35 you’ve got more than just a cam selection decision to make. What are you really going to use the vehicle for? What are you looking for a final horsepower number and how are you going to drive it? Is this a full new rebuild or just working with the engine in its current condition?
I got a question. I got a 408 small block Chevy. Vortec heads With some bowl work. Flatappet Howard’s cam 480/488 231/235@.050 108lsa. I have a 850 demon I was wanting to run I know it may be a little big. Not gonna race it but gonna turn it hard on the street 6500 is the Max rpm.
Yup. Your indications are correct. It will likely run rich.
What size carb and what type of carb would be best for a 4×4 off-road truck with a Ford 408W stroker? 6000 max rpm manual transmission 3.55 gears. The truck weight is about 5000
That’s a good one. As the mathematical answer falls at an uncommon number. So you’re using it as an off roader. You should have a cam profile and intake that is around idle-5500 rpm. If that’s true, then the off road 650 Edelbrock would be perfect.
Yes I could use some help with my build, I’m building a 525 cubic inch motor, I’m using a Chevy big block 427 tall deck block 4.310 bore and 4.500 stroke, I bought 26cc dome pistons, use Brodix heads, either 345cc are 366cc, 119cc combustion chamber, I’m shooting for 1.7-1.8 HP per cubic inch, any help would be appreciated, thanks
Well, based on the information in the video, what did you come up with?
Hello friend, very good video I have a 2600 cc montero, doing the calculations I get 160 inch and exploring the internet I have not found a carburetor that is offroad type with so little cfm, more or less it comes out at 220 cfm rated, if you had Any suggestions I would appreciate very much
Unfortunately you’re going to be limited to what other options might have been available on those smaller engines from the factory. I’m unfamiliar with the small engine sizes but the math still works the same. Though I’m not sure the factory replacement stuff was measured in the same way. Your best bet might be finding a Mitsubishi/Toyota/Nissan type of owners group and see what they are doing for those older carbureted engines.
@@MuscleCarSolutions Thanks a lot friend, both for explaining and answering me, and for sharing your knowledge
@@lastcrew213 sorry I couldn’t be more helpful. Best of luck!
Love your content, I have an 86 cutlass supreme with 307, nothing else done. It would not run with the q-jet, so a friend gave me a 1406. Not looking to race, just have a little performance and decent gas mileage. I think this 1406 is way too big and getting about 10 mpg, where I used to get 20 mpg with the q-jet. Again love your channel and thank you.
Yup. 600 CFM on a 307 is over carbureted. Get a 500 and tune it. Thank you! Glad you’re enjoying it.
@@MuscleCarSolutions great thank you, which 500 do you think; 1901
@@GrandeTime yes go with the AVS2. Either manual or electric choke - your choice.
i had a carter AFB 500CFM carb 20 yrs ago on my 80 impala sports coupe and that had what they called an "Rv cam" 204/214 duration @ .050 and that was more than enough had the stock freeway gears stock heads and i found a cast iron 4bbl intake
I have a 1978 ford weekend fun truck 2wd
460 .040 over
Flat top pistons to
bump compression of the
Stock 3dve heads
Performer rpm Intake
Holley 750cfm vacuum secondary
1970 straight up timing set
Headers 2.5” dual exhaust
Manual transmission 4800-5000 rpm max
Runs good But is old and was thinking upgrade
Since I have no other carbs to compare it to , I was considering an 800cfm edelbrock avs2
Maybe. But that’s a very mismatched intake. It works from 1600-6500. You’d be better off with the performer that works off idle to 5500.
Got a Ford 300 that i plan on keeping the internals mostly stock, just playing around with porting and cleaning up the factory manifolds, in your experience are the 1 barrels that came on these engines decent or should i ditch it for a smaller 2 barrel?
Boy I’ve had great luck with the 300s in the past. No kidding. I drove a cargo van from Dallas to KC with the factory one barrel zip tied onto the manifold. Somehow they vibrates loose and was stuck on the side of the road and zip ties to the rescue. Honestly unless you’re really make some big changes; cam profile, CR, you’re likely going to be ok with the factory carb. If you get into those areas, that’s when I’d look at a slightly bigger carb.
Does a throttle body like the one in this video have the same sound as a 4 bbl carb does when you open it up driving using a low restriction air filter.. Thanks for your time
Not especially. If that’s all you’re interested in, the best way to get that “sound” is with an old Quadrajet. That’s what you get when you have massive secondaries. Big rush of air and the sound you’re after.
@@MuscleCarSolutions Thank you for your response, I have a 1968 GTO I had back in high school. I drive it a lot I don't race it just enjoy driving it and occasionally hammering down and going through the gears. Reliving my teens. I'll stick with the Quadrajet. Thank you again
@@britknowles6530 the Qjet has an awesome sound to it no doubt. Those days are fading quickly. Glad you’re sticking with it! Great carburetors!
Im needing help ive got a 1986 Pontiac Trans Am it has a built 355 Chevrolet motor from 1975 has mechanical fuel pump right now I have a holley street demon 625 cfm on it and I'm having trouble with tuning and I don't know if I'm going with the right carb set up but it's 355 cubic inch with a 6,000 to 6,500 RPM range. Running 93 pump gas motor can also run 110 race gas not sure if that's important mostly street use with some time on drag strip but mostly street can you help car has 373 rear gears with a posi lock
What did the math tell you? Sounds like you’re right in the ballpark of where the car engine needs to be. How does it drive? Are you losing power before you get to 6500? What are the cam specs? This a drag race only vehicle?
I have a 1965 impala 283 stock what kind of carburetor do you recommend My car for is a cruiser but also would be nice to have a little muscle when I need it
Cool. What did you come up with based on what the video taught you?
Howdy. Just found your channel, subscribed and will be viewing more episodes as time permits. I'm taking a bit of a backwards journey from the bigger, faster, louder way of thinking. Car is a 65 Chevy Two station wagon with a 350 topped with Edelbrock Performer RPM heads, intake and 1411 carb. I have removed the RPM cam and installed a Summit 214/224 mild "RV" cam, chucked the 350 turbo for a 700R4 and am currently rebuilding a 1406 carb for it. I drive it a lot and with fuel costs what they are, MPG is important. It cruises the interstate at around 2400 RPM, has 18 in. idle vaccum but still is lousy on gas. The 1406 has factory tune jets/ rods/ springs. Any suggestions? Anyone else shooting for more MPG not worried so much with ET anymore?
Doing the math real quick, I come up with a 405 CFM being sufficient.
If fuel economy is truly what you’re after, a 500 would have been the better choice. But aside from that, the next video you should consider watching is th-cam.com/video/vSfAbSH9NQk/w-d-xo.html
It’s the way the OEs have gone after the growing restrictions on economy. Keeping the operating rpm as low as possible will increase fuel economy. Less rpm means less fuel used. So a modern 6 speed would be an even better choice. You’ll see the largest gains in the trans. Welcome to the channel! Eager to hear how your quest goes for more MPG!
Can you tell me some of the symptoms of over sized carb. I have a jetboat with 750 on it 400 chev mild cam and have never got it to run properly. have tried 3 different ignition systems on it because it has a nasty mid range misfire. Sounds like dizzy going nuts. Jet pump stops it going much past 4ooo rpm at full throttle. No miss at full throttle. Is midrange lean miss a symptom of too large a carb. Any help appreciated and have you seen this happen.
Overly rich condition. In ability to tune it out. Gas in the oil. Fouled plugs. Black smoke from the exhaust.
@@MuscleCarSolutions What about the mid range misfiring is that a symptom you have seen?
@@blurtmenow potentially but you can’t limit your investigation to one system. The ignition is a big part of that and you’ve got to consider something wrong there as well. In fact, I’d start there before doing any tuning or adjustment to the carburetor. If the ignition is not working properly, doesn’t matter what you do to the carburetor.
@@MuscleCarSolutions Thank you for your help with this. I will be checking heaps. Voltages and wiring mainly. I have access to a 600cfm and will take it along if it continues to play up will change it out to see if there is any improvement.
@@blurtmenow get that ignition system right first!
Ford 302 bored 30 over manual going to use a t5 with 3.55 gears in a ford ranger. Looking for a torque cam and wanting to tow/haul with it and also just daily drive it. I was thinking a 600cfm would be great.
If you’re using a smaller duration cam that’s typically all in by 5000-5500 RPM, the 600 or new 650 AVS would work just fine for that application.
I'm thinking the melling 24110. Advertised intake is 282 and advertised exhaust is 298 with an operating rpm of 1,200 to 4,000. The factory cam is advertised intake is 283 and advertised exhaust is 273. Max rpm id go is probably 5,000 for either cam. And could you tell which cam would supply more torque at lower rpm?
@@cargeekscott1871 I’d need to see the specs at .50 to know which would be better on the low end side.
@@MuscleCarSolutions the stock is 186 intake and 197 exhaust and the melling 24110 is 210 intake and 211 exhaust
@@cargeekscott1871 that is a very mild cam. Should be all in by 5000 rpm. Should be just fine with your combination. Just know that the cheap cams are typically valvetrain noisy.
Great info as usual! Appreciate all the knowledge you share with the car community, it really really helps!! Thank you and cheers from Motown. Oh, new subscriber and hit the bell.
Nice! Thanks for that. Just years and years of being around it and making many mistakes. Glad you’re here! Don’t hesitate to ask any questions. I try to answer them all. Motown thawing out and summer is almost there!
@@MuscleCarSolutions We have hit over 80 this week and set records. Scrambling to get my Mustang full spool out and go with a LSD so I can turn the darn thing. Also struggling with Deadhead or Bypass regulator. Probably Deadhead with gauge port Holley 12-840, if any problems will do bypass over winter. Mild built 460, RPM performer, Holley 4160 750,MSD 6al, C-6 manual valve body, full headers, 3" into magna flows, nodular 9" 4:11 gears, 4 link, was ex 8 sec race car, streetable now. Thanks See ya soon.
@@robertclymer6948 sounds like a heck of a fun ride!
So glad I stumbled across this. I'm building a 351w for a 92 f150 4x4 AOD transmission. I'm running a .513 lift 270/276 duration 110 lobe separation roller cam. Stock Gt40 heads with a spring kit an edelbrock performer intake. Motor will be natural aspiration. Cam is rated 1500- 5500 rpm and intake is idle - 5500. It will be a daily driver and toy hauler. I have an edelbrock 1405 600 cfm sitting my shop now, but im wondering if I should step up to one of the new avs 650 cfm. Great content btw.
I’m glad you found it too! I don’t think you can go wrong with the AVSII. Sounds like for what you’re doing the 650 will be exactly what that combination is calling for. The windsor engines are exceptionally versatile and should deliver everything you’re asking from it!
I built a 351w 0.030 over 9.6.1 with a typhoon hi rise Intake. I also am running the same roller cam and I put it in my 87 f150 4x4 with a C6 and 3.55 gears. I have tried a 750, 725, 600 and currently using a 570 (all carbs are Holley) so far I think the 570 works the best.
I have a 1986 Buick regal 3.8
Looking to buy a new carb
Any advice ? On what and where to buy ? Thank you !
Factory.
Love the video. Would love some input on my situation. I have an 87 suburban with a mild 454 BBC. Mild cam, long tube headers. Running a 4 speed manual and it’s also on 40 inch tires and 4.10 gears. (needs 4.56) Just a cruiser/ off-roader that I never take above 4500 rpm. But I do live in the mountains with lots of decent grades where you really need to roll into the throttle to get it to move. I ordered a Holley 570 street avenger because of the low rpms I consistently run but I’m second guessing myself because of the load it sees with the hills and grades. Any ideas would be appreciated!
Get a Performer intake, not an RPM or an air gap. Just the regular Performer, they have faster air velocity that makes more torque.
307 Small Block in a 3/4 ton manual 4 speed GMC pickup. Street drive only with a mild RV cam. Thanks for the great information.
Yup. You’ll have a much smaller CFM carb on that application for sure! Thanks for watching! Glad you found it useful!
I'm running a hot setup on the street. It''s 468 big block Chevy with a 7,000 RPM range. According to the formula it equates to approximately 947.9 (950 cfm). As of right now I am running a 950 carburetor. Pretty much spot on. However, I'm running a FST 4500 series 950. My question, is there a big difference between 4150 style base plate, and a 4500 style base plate? The car loves the 4500 at high rpm.
Thanks so much for the info . I have a 460 that I want to put an Edlebrock carb on .
I’m building a 302 with stock e7 heads upgraded valve springs and lunati voodoo cam. Intake is .549 lift and exhaust is .565 lift and duration at .50 is .221 intake and .227 exhaust. Engine is going in a ford ranger with a m5r2 manual trans and 3.73 gears. Truck will be a street/daily driver truck. I’m thinking a 600cfm would this be about right?
Depending on the math, any other additional equipment to support that cam profile and how you plan on driving it, yes a 600 could be perfect for it.
Thanks for the awesome video! I have a 289, uprated cam but nothing too aggressive in a 1931 Model A hot rod. Pretty light car, I would guess around 2200lbs and its a automatic. Currently has a 600CFM Edelbrock Performer and I’m thinking about moving to a AVS2. Its street driven with 91 pump gas. Thinking a 500CFM?
@@349a4 probably. But also need to know the cam specs so you’ll know what the engine is capable of RPM wise.
@@MuscleCarSolutionsI appreciate the reply! The car is new to me and the internals are unfortunately unknown. It has a very slightly lumpy idle and it still pulls well off idle which is all I know about the cam. My assumption is pretty mild but bigger than stock. I calculated with the assumption of 6500rpm.
@@349a4 so in this case, you can just go by how you’ll drive it. If you’re going to put it on the cams redline often, then yes use that rpm number to calculate your decision on a CFM size. If you’re not planning on driving it that aggressive, then you can use that number. If you go the second route and you have a situation where the math gives you a number in between two sizes, then go with the bigger option.
Awesome and enlightening video! I recently purchased a '67 GTO with a 400ci and Edelbrock 600cfm, intake and a 2004R w/od trans. Runs rough and runs on. I'm now running 93 octane and I'm thinking a Holley DP 750cfm and new TV cable/throttle setup. Am I on the right track? TIA.
Don’t know. What was the size CFM you got from the information in the video? What are you using the vehicle for? Drag only? Cruiser? What have you done to address the running issues you’re having? I’d be a lot more concerned about those before I made any carburetor changes.
@@MuscleCarSolutions I’m looking at 400ci at 6000rpm w/93 octane came to a 750cfm. Definitely a cruiser. I’ve run the higher octane and even tried Seafoam but to no avail.
What’s your timing set at? Initial and all in?
When that thing was new, it probably ran great from the factory using a stock 750 CFM Quadra jet. I know gas today is not as good as it was in 1967, but the engineers at GM knew a thing or two. I would try a QJ.
Would you recommend a 500cfm carb for my chevy 350? I got a edelbrock top end kit with a max rpm of 5500. But i don’t even rev that high on my K5 blazer. If anything i never even see it pass 4000rpm. Im currently running a 650 avs2.
Put that size carb in similar applications all the time. As long you you’re driving it that way, you’ll get good results. If you’re aggressive with it, the 650 is also a good choice.
@@MuscleCarSolutions I appreciate your advice. I guess ill stick to my 650 avs2. I do go off roading but just havent taken the blazer yet. Still need to watch your video again regarding the off roading modifications to the avs2.
Hi, very good explanation of how the carburetor works and how to do the math .
I’ve got a 65 Olds Cutlass with a olds 403 .060 over, headers , olds 350 heads w 65 cc cambers 9.1 :1 , Edelbrock performer rpm intake, Carter 750 , isky 262 / 262 cam , stock rear ended , HEI
TH2004r w lockup converter.
Runs so so. I did the math and it looks like a could go with a 625 or a 650 CFM Edelbrock
408cid x 5000rpm
3456 = 590.2777
Any suggestions?
Thank you for your time and efforts
Job well done.
Ernie
Kind of really depends on this one. I’d probably step up to the AVS2 and go with the 650. You’ll get some better throttle response with the annular discharge carb. Should have no trouble tuning it for that fun Olds motor. Big fan of any of the BOP engines and cars. 👍
@@MuscleCarSolutions thank you very much for your prompt reply and time . Always a pleasure to talk with someone who has been working with this kind of thing . I’d send a picture of my car but this site won’t let me .
Take care and be well
Regards Ernie
@@erniehampton5809 always happy to help!
Hello, I have a 406 w5.7 rods, in 71 monte carlo. Car weights 3710 with driver. 331 gears, 3800k stall. 750 qf dp. AFR 195s, 10.8 cr, 1 5/8 long tubes. 2.5 dual exhaust. Rpm airgap.
Cam is a comp 294 roller. 1.5 roller rockers. I don't take past 6k. I was thinking of trying a vac secondary 650 carb? The dp works great, I tuned it using a wideband O2 sensor. Just thinking of it would be more effective with the smaller carb.
What do you think? Best on the draggy was 12.68@ 110mph with 2.2 60ft.
I think the carb size might be the least of your worries. Which cam is that? Has the 110 LSA?
@@MuscleCarSolutions lift 540/562 dur 242i 246e. And yes 110 lsa. Jetting is 70 front, 77 rear. Like I said it runs awesome, I just wonder for a street car, that I over carbed it on what I have researched and carb math from your video. Wondering if a 650 vac secondary would run the same just cruising. Hate to buy one just to test. I decided on the double pumper because the converter flashes at 4k wot, figuring the same as a clutch dump needing the fuel sooner to meet demand.
It’s really hard to say when the rest of the combination is questionable. That cam doesn’t match up well with that converter. If you’ve gotten it to run ok, I’m not sure I would change it. You’ll end up fighting it.
@@MuscleCarSolutions I know I would fight it, that's why I haven't done it yet. Lol, my OCD. And depending how the overdrive goes, I may change to 3.73-4.10 gear. What converter would you lean towards. Mine is a nitrous converter. The builder didn't receive the parts in time, so I got a free upgrade.
I have an 1977 c20 with a stock 350 manual 4 speed with 3.73 gears I do pull a trailer that’s about 3800 lb , I was thinking a holly 500 cam 2 Barrel when pulling a hill I drop a gear hold rpm around 4200-4300 What carb would you recommend
The formula in the video is the place to start. Is 4300 your max rpm on that engine?
Yes
I’m having my 5.3ls rebuild with a mild cam heads all that good stuff. Thinking of switching to a high performance carburetor. What size should I use. I think I have a 650 double pump on it now
What did you come up with after watching the video?
Brian, great video! I am working on my all original 1956 Ford Ranch Wagon, has the 292 V8 engine with the 3 speed manual transmission, it's a rebuild, but stock, nothing hi performance. I'm wondering which carburetor to go with, any advice? Thanks Brian!
Probably right back to the stock one would be your best choice. What did you come up with when you did the math?
@@MuscleCarSolutions 450-500 cfm The previous owner installed this cheapy 2 barrel carb., original carb was a 4 barrel, original carbs for the 292 can be costly
Thanks for all the great info!
Looking to replace the Holley 600 on my 318 with an AVS2. 4 bbl intake, mild cam, headers, automatic. Makes about 5 in vacuum at idle.
Would you go with the 500 or 650?
Wow. Mild cam and only 5” of vacuum? What’s your definition of mild?? 😂😂
Mild cams don't shake the mirrors off the car. 😉😉
Guess the 650 is the size to go?
I don’t know. You don’t give me enough to go on. I have to know the details that are outlined in the video. Also what you’re using the engine/vehicle for.
@@MuscleCarSolutions Sorry about that, I will try to give more details
The car is a 71 Challenger, only ever street driven. Drive train is a 918 Automatic with a shift kit and a 3.73 rear gear.
The motor was already built when I purchased the car, I don't know the cam spec or compression, but the cam does have a lot of duration and only 5 In of vacuum at idle.
Has a factory 340 intake, and currently using a Holley 600 Vacuum Secondary, long tube headers and dual exhaust.
No boost or Nitrous
Only use ethanol free 93 octane fuel.
Top of the RPM range is 6000, and rarely do I go that high.
Hope you can help me.
Thanks
You’re kind of in a grey area there. Doesn’t help you’re running a stock intake and a wild cam. They don’t match up. The rest gear will help for sure. I’m sure it’s got to have a fairly aggressive stall converter. If that was mine and I had an intake upgrade planned and perhaps a milder cam that would allow you more engine vacuum, I’d likely go with the 650 now and grow into it as the upgrades happen. You’re in a not uncommon situation. But in this case, I’d go larger. The smaller carb would be just fine but it would limit your rpm and that cam. Bette run run a little rich than a little lean.
I have a sbc 355 30 over I don’t know what carb to use could you help please 🙏
@@crfisaiah3963 sure! What did you come up with based on what the video taught?
@ well I learned that I need it to be tuned for street driving besides that I haven’t tried to do the math yet
I’m trying to build a 351windsor with a twin turbo application build out converting to roller, and plan to run about 15-20psi mostly for mountain claiming in winter with a camper on a f250 1991 think a 650 blow threw will do the trick or something bigger ?
Have the same proyect, Just single turbo!!
Thanks for the content! I’m building a factory five car. The final weight is going to be about 2200lbs. I’m running a 347 sbf with a 5500 redline it’s going to be a purely street car. It’ll be mated to a tkx and irs with 3.55 gears. The math leads me to a 550 cam carb. Is that a good choice or would you recommend something else?
600 is good on a street driven car. Might step up to a 650 if you feel like that’s going to change once you get a taste for how fun it will be.
What about splitting the difference with the street demon 625?
@@Doclittle1036 that’s up to you. I hate that carburetor. 😆
Thanks for the advice. I’ll stay away from the demon
@@Doclittle1036 I did a video on the things I don’t like about it. Others have had success with them, but to me they aren’t worth the effort. It’s my bias, but I tried to give all those details in the video and the viewer can decide if it’s worth it or not.
Hi, I just came across your channel while watching one of uncle Tony's Garage's videos. After watching some of your videos, I was wondering if you might be able to help me sort out an issue I'm having. Here's what I have. It's a 1 ton dually with a 454, a manual transmission, 670 street avenger and 4.56 rear end gears.
The issue is a lean spot just before the secondaries open. I've tried going to a black spring which is the stiffest. It got rid of the lean spot, but I don't think the secondaries are opening.
I went one step down to the brown spring which seemed help, but there is a slight lean spot still and I can distinctly feel the secondaries open. Also with the brown spring, at times I don't get a lean spot, but I can't say for sure the secondaries are opening all the way. I don't know if the lack of a hit is misleading me compared to when I get the hit after the lean spot. All this is going wide open throttle from a slow roll at about 1200-1500 rpm. My engine has peak hp at about 4200 rpm and I don't really ever go over that.
When I go wide open throttle at say 2000 rpm and say 30 mph I can't say I ever get a lean spot.
Im not sure what other options i have.
Thanks for your video's, I've been enjoying watching them.
Which carburetor are you working with and what size?
@@MuscleCarSolutions 670 holley street avenger
@@MuscleCarSolutions it's a 670 holley street avenger. I have about 19 inches of vacuum at idle.
I’d stick with the spring that eliminates your possible lean spot. I wouldn’t worry about if they are opening or not. If they aren’t, it will fall flat on its face. It’s normal to have a smooth transition as they open and you want that! Sounds like you’ve done quite a lot to get it figured out to this point.
@@MuscleCarSolutions I haven't done a whole lot, just tried a couple springs and put a .035 squirter in from a .031, which I'm not sure was the right direction. It seemed to clean things up, but I did notice it goes really rich (10.0:1) when I lug the motor and go wide open throttle. I'm not sure if it did that before though.
I went out and drove it again, I think there is considerable amount of power difference between the black and brown spring (brown spring is lighter) It sounds different too. It also revs cleaner and faster and doesn't sound like it's struggling so much to gain rpm.
The air fuel ratio goes to a about 15.0:1 before the secondaries open all the way, it still pulls pretty good up to that point. I think im losing some power though.
Would going from a 6.5 power valve to a 7.5 maybe clean up that lean spot or am I past the opening of the PV by time i get to the lean spot. I wish incould watch the vacuum gauge at same time as the AFR gauge.
Any thoughts would be appreciated even if you still think I should stick with the heavier spring.
I have a 360 30 over probably 6000 rpm what size carb you think would work good going to drive it to car show and such
Well. What did you come up with after watching the video?
I wanting to get a bigger carb for a 350 sbc and I plan on keeping it stock and just road/off road but mainly on road other than the carb and hopefully the intake, when I did the equation I figured I need a 500cfm, but I'm wondering if that would be to much for it or if I could just go ahead with a 600cfm
That’s ultimately going to be your decision. This is really made to get you in the ballpark. Off road use is usually an RPM range that can vary. Off idle to 4500 max. Lower rpm doesn’t require as much CFM. If you w got upgrades planned down the road then it usually best to pick the bigger size. Don’t be afraid of running the smaller size if that’s all you’ll demand of it.
@@MuscleCarSolutions alright, thanks
Also another question I just thought about should I go with a holley or an Edelbrock I've heard good and bad about both
@@noaha2430 off road I’d stick with the Edelbrock. If it was an off road race truck, then go with the Holley. Two different types of carburetor with much different applications. The folks who say one brand or another is junk probably can’t tune either one.
@@MuscleCarSolutions Alright thanks for the help
What do you think my 95 mustang gt with the 302 and b303 cam needs? Using the math I’m gettting 524 cfm without factoring in the cam
That’s about correct for that cam. It’s very limiting with todays better lobe technology. Depends on how you want to drive it. Just a cruiser? A little more aggressive driving? Then a 600 will probably be just fine.
@@MuscleCarSolutions I’m planning on fixing the car up and getting used to the hp. It won’t be carbed for too long. I just need it to run good for right now
Will a 750 (CFM???) Edelbrock for my soon to be machined /rebuilt 1970 472 V8 Cadi CDV (keeping engine as OG as possible and boring only)? I've been advised to go electric choke too, so will I need press. reg, and electric fuel pump too or can I keep my og mechanical fuel pump? Thanks for awesome Vid I think my calc for CFM = 601. [472 X 4,400]/3456= 601 This car will run. 91 gas, mostly cruzin to shows and with low riders, but want to drive say within 100 miles distance on freeway 70mph. Thanks again from Sunny SD, Cali. Cholo Clem
Go with the 650 AVS2 carburetor. Better choice for what you’re doing.
hey guys, thanks for the shows. ive got a 1965 283 , .030 overbored, studded bottom end, summit k1102 cam set ,520 power pack heads freshed up with new valves and z28 valve springs, intake is a 1966 factory GM 4bbl squarebore designed for Holley use from a 327 (is it possible its from a corvette?) because the ports match the pp's way better than the other intakes i tried. I already have a Holley 600 that i plan on using . what tq/hp do you guys think i'll get out of this combination?
Unfortunately the sub 4” bore engines don’t make very good power. That limiting factor really kills the potential, no matter what you throw at it. I don’t know the specs on that cam but I’d guess the power will be under 300.
Do bolt on parts play any type of roll in deciding what size carburetor to go with? I have a SBF 302 with shorty headers MSD box, dizzy, and ignition. 2.25 exhaust from header back out 3" mufflers. AOD transmission. I bought the car as is with a Edelbrock 650cfm. Not sure if any internal work, however is that the right size Carb?
Sort of yes. It’s parts that indicate Joey ours going to drive it, usually. Depending on what you do go with it can make a difference in the size carb you choose. Based on the video, you tell me if that the right size carb. You left out details that will make that determination.
Hello there.
I bought the Edelbrock 1406 (600sfm) to Ford Torino 351 Cleveland, and I think it doesn't ride as good as it used to on HOLLEY.
Is that 1406 good enough for that engine???
Please HELP..
Yes, no, maybe. I don’t have enough information to give an opinion. Watch the video and do the math based on what you have and we can talk about it.
Is that a 2v or 4v 351c? The 4v cleveland came standard with a 4300d autolite carb 750 cfm spread bore type. I have a 1406 600 cfm edelbrock carb on my carb. Im not crazy about the carb. Im wanting to go different might try a street demon or 750 cfm holley
if i used the first equation, thats what id wanna use for a mechanical secondary
i just multiply it by VE 1.1 and get the bigger carb BUT its vacuum secondaries. a double pumper flows way more fuel vs a vac secondary of the same size. freiburger and company tested a 750 dbl pumper vs 750 VS MS made 20+ more HP with no other changes other than the carb type
so just up up in size on a street carb this all N/A pump gas 91-93 octane
The formula, no matter what is used, is going to be a ballpark result. This one is easy to understand and is a good starting point to determine what direction the user needs to go size wise to get the best CFM. Certainly a race application will look at race carburetors and not the VS models. Fortunately is a wide spread on sizes. Hard to get too wrong. The alternative is what I see time and time again. Someone talked them into putting way too much carburetor on their application. The street guys always seem to have the most trouble.
@@MuscleCarSolutions yeah ive read about a lot of guys going for too much carb.
i figured a 6500 RPM 302 with 4.10's and a 3000 stall and aluminum heads and about 10:1 a 600 dbl pumper would work in a 2900 lb car with me in it @ 3100+ mercury zephyr
close enough i guess
Depends on what you’re going to use it for. Sounds like you’ve got it dialed in. I’d trust a 600 to tune through those things you mentioned and the aggressive driving that it’s built for.
@@MuscleCarSolutions yeah I'd say it's gonna be "hot street" somewhat MAYBE a couple of track runs but nothing serious. Just want it to get up and go pretty decent for a fox body on the street
What happens when you port match and polish the intake and heads for more flow?
Port match? You’ll gain a little on the top end. Doubtful it will change a CFM choice but it will be something to consider along with all the other factors in selecting a CFM.