The Holley Carb Adjustment That Has A Twist - A Seemingly Simple Variation With A Big Difference
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- เผยแพร่เมื่อ 29 ก.ย. 2024
- Adjustable float height is one of the features that set Holley style carbs apart from the rest and can add an edge when fine tuning for performance. But, there are a couple of different procedures based upon whether your carb is equipped with sight plugs or a sight glass.
Here's why they're different and how to work with each.
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100% correct. I work at Holley and completely agree with.
I'll pin this, Dennis. Thank you.
Ok, but never break loose the locking screw to adjust fuel level with car running or fuel pump on, at least not in a how to explanation. Now after doing it a few times you get a feel for loosing it and turning hex and not getting sprayed with fuel.
Other thing not mentioned, holley used crappy paper washers that stick to lock screw and adj nut, so the second you break them loose the paper washers are junk, because they just tore in half and will never seal agin.
Great 👍 Have questions for you maybe you can help?
Although I agree that with a sight glass carb, adjusting the float down will raise the fuel level in the bowl and give you a wacky reading,.... EVERYBODY KNOWS YOU MUST RUN THE ENGINE TO STABILIZE THE FUEL LEVEL!
Even if they didn't know that, after they take it out for a test, they'll see the level is off, then readjust the float level.
Anyone with a carb, with a sight plug would know this, or they would never attempt to adjust it, not knowing that.
Anyone who doesn't know to stabilize the float reading, would also not know what the bloody level should even be! They wouldn't even know that it's even adjustable, or where or how to adjust the floats!
I love your vids, but this vid was not needed lol.
Jake, you're wrong. The time honored method of adjusting the float height with a sight plug is to shake the engine side to side and let the excess fuel dribble out, then continue with the adjustment. Waiting for the engine to consume the extra fuel, ESPECIALLY on the secondary side is a foolish waste of time.
Now, the reason I made this video, was because I had just watched a video where an extremely well known TH-camr adjusted the secondary float on a sight glass carburetor clear down to oblivion and as a result developed a "mystery problem" that completely choked off his engines performance.
After scanning through over a thousand comments on that video, and seeing that not one single person caught the oversight, I felt compelled to make this one.
Like #99!
Never knew that about lowering the float displacing fuel like that! I've always just had sight-plugs, but concede that the sight-glass is better.
Anytime you lower the float you want to let it idle and even out the float bowl on its own. It does work with a sight glass style, you do not have to drain it but that way is definitely faster than waiting for the motor to consume it. Raising it is always way faster so I'll set a new carb up with them intentionally low so it doesn't take as long to get them set once you start.
rev the engine, the accel pump will take care of the extra fuel q u q
This is what I was thinking. It just takes a little patience.
I was wondering, that what keeps the motor running if the fuel does not come out from the float chambers. Well there is a few other things i dont understand.😳
@@leadfoot5427 Exactly. I was just wanting to point out that Tony saying the only way is to drain it and start over isn't true. I think he may not have meant to make it sound that way but it's how it sounded to me.
I love your carburetor videos, I’ve learned quite a bit! Thanks Tony!
My 65 bigblock Corvette came with a Demon 750 carb. Every time I hit the brakes even moderately hard the engine died. I adjusted the floats up and down and installed a Holley fuel pressure regulator and nothing helped. I installed a Summit Racing carb I had lying around and problem solved.
Raise the fuel level the amount that you want to reduce it.
Carburetors are the best analog machines ever built. DO NOT ever stop talking about them. Anybody who has a trouble with carbs can get back in their riceburners and go to hell.
yeah, but with todays gas carbs can be a pita for cars not driven a lot. I see the benefits of both systems.
I've adjusted sight glass carbs back down while the engine was running, had no problem with it.
So long as the engine is sucking fuel out of the bowl, it has never been a problem for me.
I have about six carburetors laying around I have to start rebuilding I have my notepad and pencil ready 😂😂😂 keep it coming
How in the world did you get yourself into repairing 6 carbs without already knowing carb basics?
I greatly admire your confidence
@@Onewheelordeal gotta start somewhere 😂😂😂
There all mine too lol old one I never through out
Tony! You just solved a mystery I've been wondering about for 25 years! I got a pile of old holley carbs and parts with an old 63 Maxwedge I bought in the 90's, some of the sight plugs were drilled and tapped and were plugged with a 1/4-20 screw and rubber washer and no one could tell me why. Now it's obvious that with the whole plug out you adjust the level for the street and with just the screw out the bottom of the hole is higher and you're set up for dragging. Neat
The world started turning to crap shortly after Carburettors started disappearing from production vehicles. Bring back carburettors and maybe things would turn back to what they used to be.
Can we bring back distributors to? Purdy please
The Holley clear sight plugs make life much easier.
Great tips.
I used the old holly carbs with the screw in plugs on our circle track car I found a business card or a finger covering half the the hole worked to set the floats. Once you got it where you wanted just screw the plug back in.
On circle track cars i also remember modifying the floats so they wouldn't flood the motor on the curves by making them a wedge shape.
UNCLE TONY, YOU ARE A WONDERFUL PERSON
Maybe I miss the episode but you never even mentioned the nitrous on that 361 that was the 361 correct
I have not talked about it yet. When we introduce the car it's going in later this year, I'll go into all the details. And yes, that's the 361
Who blames squirrels?
Uncle Squirrel will
It's always the squirrel's fault 😂
I blame them for inflation.
or any other animal that nested in my cowl or under an intake manifold.
@@DanEBoyd nah... That's the potato's fault! 🤣
Good video. had to laugh at the last bit where he says glass is nicer than having gas trickling out all over the motor...says the guy who squirts bottles of gas all over the engine looking for vacuum leaks..lol..
While smoking a cigarette!! LOL Its all good.
Wait... I saw those metering blocks, is Tony going to join the shine side?
While I understand exactly what you are explaining about float displacement giving a false high reading. Wouldn't the engine consuming fuel out of the bowl equalize this given enough time? It almost seems as though you are explaining setting static height with an electric pump, rather than dynamic height, engine running?
See, that all depends. I suppose you could wait while the engine consumes fuel, but that could be a fairly long process, and wouldn't apply equally on all carbs. For instance, on a vacuum secondary carb, the rear bowl would take an eternity to drop. Less so on a 4 corner carb, but it would still take some time.
Minor quibble, but it's important to get the terminology correct to minimize confusion. You said you're adjusting the "float bowl" multiple times starting at 2:12, but you're not adjusting the float bowl, you're adjusting the float. The float is inside the float bowl, which is the housing.
Uncle Tony....are you appropriating the 1958 Edsel's engine color for that big block Mopar?
A benefit I've had working on so many holley carbs in the marine industry is that has been the only place I ever seen them use an anti-splash baffle at the back of the float. They make a world of difference when used on the track.
It probably would O.F.F. road too, I wasn’t aware this existed.
Off road… I’m not sure what autocorrect was thinking.
One thing irritates me, when comparing the glas-style with the plug-style fuel bowls. their locations look very different to me. it seems like the bottom of the plug-style hole is around the very upper quarter of the glas-window-style.
if so, how can the fuel bowl level be the same for lower third of glas-window and the lower edge plug-hole?
I'd love to see you do an in depth video on the T quad.
Holley sells the clear plastic sight plugs to make the higher fuel level adjustment. You are supposed to remove them and put the metal ones back in when done adjusting. The problem is that many people left them in thinking they were a suitable replacement or sight glass conversion. Well they would eventually crack or break off and burn down the car. So if you do use them please dont leave them in.
My carb came with them installed and no plugs to replace them with..your claim makes no sense.
@@cuzz63 To be clear, Im talking about the clear plastic plugs that screw in like the metal ones, not the many different types clear bowl site windows. If youve got the clear plastic screw in plugs I would replace them with some brass ones. Its only like 5 bucks. Holley does not sell the clear plastic ones anymore. Probably because of the fire hazard if left in.
@@georgesmith739 thanks.
I much prefer this to the thousands of EFI conversion videos where the well meaning fools become servants of the silicon industry so that they can interact with everything in graph form like an office drone🤣. I love EFI but holy hell is it over promoted.
Your carburetor videos are some of my favorites. Your recent rear end videos were really good too.
The only problem with adjusting the old ones so fuel will just run out is when the motor is shaking around because of the cam, it gets hard to do.
As a kid in high school and into my 20's we all knew the "one flat out" adjustment for Holley carbs. If you have the sight glass and raised it too much do you really need to drain the bowl? Can't you just let the engine burn some of it after lowering the float? Or is that too slow? Seems like the accelerator pump with the engine running would lower it pretty quickly.
I would be happy with more carburetor videos! I want to learn all there is to know about them. Even if alot of would be irrelevant
We usually wacked the throttle a few times to use some fuel up but it was with an electric fuel pump.
Can you do setting up carburetor for turbos?
Personally I blame squirrels..and no video notifications
I had this issue with an Edelbrock Performer years ago. Car would start and run but it blew black smoke out the exhaust under load. After about 30 minutes of driving it would stall and I wouldn't be able to start it again unless it sat for a day. In hindsight this was OBVIOUSLY a flooding issue but I didn't know anything back then. I replaced the Edelbrock with a Quadrajet that I knew was good and called it a day.
Fast forward to a few years later: you dropped a video about how to use the Edelbrock rebuild kit and it encouraged me to buy one and pull that old Performer off the back of the shelf. Turns out one of the floats was just absolutely torqued so the needle and seat would never close. Previous owner did a real hack job on it and I didn't know enough to figure it out until you posted a how-to. What I'm trying to say is don't hesitate to do carburetor videos!
What the hell is Tony doing with a NEW Holley XP E85? Was this sent as a freebie?
Tony, how come you can't lower the float a little while reving the engine to lower the fuel level. I'd imagine it wouldn't work if you really over did it but if it was just a little high wouldn't it work?
NOT ANOTHER CAEBURETOR VIDEO! Just for you, UncT!
I got something outta that
Got any hot tips on changing Holley throttle shaft bushings?
if you didnt post carb videos i dont know if i would have found you
Thank You Tony. Gonna add this to my investigations, process of illinations, why my car wants to lay over at about 5k. 750 vacuum secondary. Can't Gunfight with it doing that.
Tony, i will watch every carb video you do. I learn something valuable every single time.
Uncle Tony, you can never do too many carburetor videos, said the guy headed outside to redo his float height.
Plan Z!!
You won't find me complaining about a Holley carburetor video. I have some dialing-in to do on my 65 Travelall, so I'm all ears. Oh, and eyes too I guess.
I dont have any problems with holleys
PLEASE MORE CARBURETOR VIDEOS!!
I'm working and I'm saving. There's a classic American machine out there somewhere just for me.
🤞 And I can't wait.
UT could you do a video on summit carbs ?
I got something out of that. Thank you Tony.
Engines suck, carbs put out.
Love me a good carburetor video!
Ok Tony I hate to bring this up but someone has to ask it. Do you set the secoundary the same way? As to height?
Yes I would also like to know this
Great video, brother.
I can see people not knowing this info amd chasing the fuel level on a sight glass carb forever. Thanks Uncle Tony
Yes!! Another Carb video!
I blame the squirrels
Hi Tony, thank you for the great videos! I just installed a correct date coded Holley 4053-DZ Dated 942. It seems to be missing the choke rod that goes to the intake, (it is a 1969 Camaro Z/28 with 302 engine), I am trying to get the car back to "factory" as possible. Do you know where I can find one? Any help or advice would greatly be appreciated. Thank you!
Keep the carburetor videos coming. I'm having difficulties with idle on my demon carb sitting on a 496 stroker... Appreciate your videos 👍
If you don't have a sight glass Saran wrap pressed over the hole works pretty good for an accurate reading, obviously you're going to spill a little gas once you have it adjusted but that's what paper towels are for
I always installed “vent whistles “ on drag racing Holleys. They help avoid the flooding when exiting the burnout and doing dry hops.
On my carb, (electric fuel pump) the fuel level seems to go down below the sight glasses when motor is not running.
Question 1: Should it be like that? It has never caused any problem. Car is very easy to start.
Question 2: If No 1 is ok, why can't I just adjust the floates down a bit with engine off, then start the car to check if I hit the correct float level? To me that sounds much easier than draining the bowls etc...?
Or am I missing something here?
I never messed around with Holley carbs.. crazy huh… 40 years of messing with engines.. I acquired a quadrajet replacement spread bore Holley .. NOS 750 cfm. Now I have some more basic knowledge in case I use that carb on one of my Buicks… however I am one of those quadrajet nuts… 😁
You just tweeked my racing knowledge one flat backward. There is always place for improvement, if not reinforcing the existing one. For the Backyard DIY mecanic, we dont set caburators every weeks. Well actually we do but not always the right way! Next stop.
Miramichi dragway park in May. After the snow melts.
I don't have any newer carbs but I thank you for your help GODSPEED
Im all for more carb videos. The more i can watch before my engine is done thr better
You can't do enough carb vids.
Couldn't you just disable the full pump if electric or unhook if mechanical? No mess on your engine with leaking fuel then.
6:14 DRAIN THE GAS? No no no. With a sight glass, if you go to far just keep the car running while you adjust the float back down but WAIT long enough to burn the gas out of the carb and recheck. Always easier to wait and do nothing than go out of your way to drain gas all over the top of your hot engine. 6:50 Good tip on the one-flat CCW to raise the float level.
Always learn something new every time I watch your videos I appreciate the information
I like your carb tuning tips. Really have been helpful for me!
But but but EFI!!!
LoL
Lots of folks want learn carburetors, and have no where to start. Keep up the carb videos. Hatters be damned
One old trick I used was to have someone lightly power brake engine and adjust to trickle out of flow plug. Seems like it gave me about right level for performance carb prior to sight glass. Always had a 4 gas analyzer to finish jetting, transfers, accel pump, power valve tining though. B4 days of AF guages.
Tony, you could do carb videos every day. I learn alot from them. Make sure to keep the 2 little gaskets handy for the set screw and nut. They rip if sitting for a while.
Awesome!
I came across this issue and thought the adjustment mechanism was broken. I could not get the float to go down. I then got it to work at another time and said to myself "it fixed itself" :) Great video !!!
Wow that is one of the things that I did not know! I've been dealing with a 7:50 quick fuel carburetor that's been a nightmare and seriously I think it's too small for my big block Chevy I've been messing with it I don't know how long everything I've tried I just can't seem to get rid of a little stumble ? Don't get me wrong I have a vacuum 8:50 on my Mustang small block and I took it off and put it on my big block and it runs great. Bot I would really love to figure out why I can't get the 750 to work properly it's just a mystery
Always been a Q-jet fan but my next purchase will be a Holley type carb. Thank you for the information.
Thank you
For clarifying
Yes ive done that as you described
I watch most of ypur videos
Thank you very much
Hi Tony…. Great videos very helpful when working on Holley carburetor’s . I’m a bit confused, I adjusted the front float bowl worked out properly turning the adjustment nut clockwise to lower the fuel level ….now when I went to the back float bowl and tried to adjust it, the fuel level doesn’t seem to lower. I understand the level artificially increasing because I’m pushing down the float. After starting the Chrysler 400 giving it throttle to open the secondary and relax the fuel level. It still doesn’t seem to go down to where I would expect Strange, maybe bad float bowl?
Thanks in advance.
Hope to hear back.
ooh E85 XP O.O
Great info, thanks! I have a new Holley 750 double pumper for my 440 that has not been "dialed in" yet.
found this video while trying to adjust a holley on a 351 winsor in a boat. great tips along with other videos from utg on it. one stipulation i had was my carb had no screw on top for float adjustment! im assuming its a fixed hight float version
I have always found that simply revving the engine enough to use the full accelerator pump will use up the extra fuel in the bowl. You could also just let it idle for a few minutes to consume the fuel. Carburetor are as difficult as you want to make them.
Now can someone explain how an engine that is physically able to only pull in 500cfm of air at max rpm can magically be impacted by bolting on a carb capable of flowing 1000cfm it would be appreciated. Physically the only way to get more air into an engine without making changes to displacement is to increase atmospheric pressure. I have yet to find a carb that is able to in ease atmospheric pressure like forced induction can. Ever wonder how oem was able to factory install 800cfm carbs on 302 engines?
Ok Tony I just put a message here and wanted to get back and say forget the question I asked you,I learned something,the billet block I asked about and I said they have the spot there,well it turns out they drill and tap and put an Allen screw in it that if you look with a magnifying glass or have good eyes you can see.put the right Allen wrench on it and spin it out and replace it with the right screw.this was much easier than I thought.thanks for the help Tony.lol
Hi, can not get the brass float adjustment screw out of my 4 barrel carb, do u think the rubber seal might bad? i do not want to mess up the threads,please advise
Wow, i have da those sight window carbs and never dawned on me to adjust as you pointed out! GREAT INFO THANKS!
AWESOME vid UT....great info ty....MOPAR 4 EVER.
It's easier and less messy to just shut off the pump and let the engine drain the fuel. That is if you have an electric fuel pump.
My hubby drilled a small hole in the plug on the old style in the center and used it raise the floats, then replaced it quickly! With a solid plug !
accelerator pump will drain the excess fuel quickly..
You really get hate mail for doing 'another' carb video? Wow. Also, those XP units have just the right amount of bling.
A whole 5 days for the next carb instalment? That’s an eternity away!
Thanks Uncle, always been a Holley guy but never knew of the correct sight glass adjustment. I’ve been tweaking with a Street demon carb and though it’s not an out and out high performance unit; it’s got precision metering and tiny primaries.
Once I had a Holley carb where the float adjustment was reversed.
The screw was the adjustment and the nut was the lock.
Is the float level affected by tilt of the engine or rake on the car?. Having issue with engine flooding out on the shut down at the top of the track. Thanks!
I now know why my brawler 650 is running rich. I thought the sight glass should be filled to the top which is how it came set. But no it needs to be just at the bottom of the sight glass. I'll adjust it tomorrow morning and see.
great vid. you can also adjust the level of a sight glass carb with the engine running. slowly lower the adjustment and give the engine time to burn some fuel, then the level will be stabi!ized.
Early type (late 50s) Holleys do not have the externally adjustable float/needle-and-seat and in fact do not use the same needle and seat assembly.
The bowls have to be removed to adjust them.
floats and fuel pressure are adjusted running .. low float = low fuel level ..high pressure = high float... the fuel wont be above the float .. bench setting the float means inverting the bowl and adjusting the float level or slightly higher to allow just raising it when the engine is idling .. in 50 years on race and street cars the fuel level was fine when the sight plug threads would get wert with a knee bump on the fender ..with a good fuel system Holley bowls won't run out of fuel .... an 1/8 inch higher level would'nt be enough to matter ..
my truck originally tbi now carburated turns off when warm and put into gear any idea how i could fix that issue