SBF CARB SPACER & INTAKE TEST
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- เผยแพร่เมื่อ 28 ก.ค. 2020
- FULL SBF RESULTS-VIC JR. VS FUNNEL WEB VS RPM + SPACERS!!!! CHECK OUT THIS VIDEO WERE I RAN TWO TEST MOTORS. TEST MOTOR NUMBER 1- TO COMPARE A SINGLE-PLANE FUNNEL WEB TO A DUAL-PLANE ELIMINATOR. THEN, I RAN THE DUAL PLANE WITH AN OPEN SPACER AND A 4-HOLE. HOW DID THEY DO? TEST MOTOR NUMBER 2-TO COMPARE THE FUNNEL WEB TO A VIC JR. AND AN RPM. LOTS OF GOOD STUFF.
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The rain in Spain. Falls mainly on the dual Plane.
Your info is invaluable when pondering what direction to take things ...your data I'm shure has been a blessing to many peoples street,dragrace,cruizers,father son/daughter projects .....so thank you...... Your passion fuels our productivity
Back in the 70's I had a Ford 302 stock car, I ran it on short tracks and the best combination at that time for me was a Weiand dual plane intake with an open 2 inch spacer topped by a 650 Holley, this setup made the car turn it's quickest lap times on the 1/4 mile ovals, great acceleration off the corner apex and superior "driveability" , really worked well.
I endured a Joe Biden dementia ad and didn't skip it. The things I do to support channels I like.
Dude... That's too much
Way too much to ask of anyone!
thnx for the support
Funny as fuck! Oh sorry we have to be nice to the sponsors
LMAO!
You are the busiest guy on TH-cam! Thanks for all the content. I'm ready to see a Gen 2 coyote big bang! Have a good one Richard
Love the way you broke it down. I totally have a better understanding of it now. I already have the edelbrock air gap for my build. I think I'm going to get the phel open spacer for mine. 351 build. Thanks so much. Keep it coming
I run a dual plane air gap with an open 1" spacer by Wilson on my 347" with 190cc 11R heads and a stage 2 cam. Thanks for the test, very helpful to see the differences.
Another excellent video Richards, thanks for sharing your knowledge.
More SBF tests!!! Budget 351w build?!!!
I know he did one with a junkyard 351 and the eddy top end kit
Made 450
@@KingJT80 Really? With a carb set up?
@@nicholasperricone6873 it was a 750DP iI think
I love the intro’s old skool banger beat. 😁
Reminds me from early 2000’s Benny Benassi 😎👍🏼
What about testing the intake spacers on the single plane intakes? I would be curious to see what a 2 inch Wilson spacer would do on the funnel web. That would turn into a single carb tunnel ram.
Great test. Interesting results on the dual plane manifold with the spacers.
Hey Richard I love your videos, very informative and fun. I know there is a lot of work that goes into what you do so be safe. I hope you can keep this up and not get burnt out, please pace yourself. I was glad to see you do a happy hour with your lovely wife having fun you deserve it. Would love to see you do an 8 stack EFI like a Hilbourn intake or maybe even a weber carb set up on a small block ford and large cubic inch 351w maybe 427 or bigger picking a good combo heads cam and so on set up with a very wide tourq band for like Auto cross, scca, pro touring type track etc. Kind a like the old ac cobras. Thanks Again!
I would REALLY like to see a manifold test on a 351 stroker, Air Gap with and without open spacer and Vic Jr single plane on a street built engine with good heads and cam. PLEASE!
Absolutely love what you are doing, keep the tests coming.
Very nice cmparison. I can see that the RPM Air gap is a good intake, fitted with an open spacer, even better. That's exactly what we've seen on all the other tests with a dual plane intake and and open spacer. I'd like to see an EFI intake shootout. Like the EFI Victor Jr intake vs the Speedmaster Shootout EFI and the Edelbrock XT vs the Holley Hi-Ram. Thanks for posting, Always a thrill to see new vids by the Dyno Shootout King!
Thank you Richard! Your the best!
Wow that was a fast turn around for the video. Thanks! I have a 4 hole on the air gap, guess ill try the open this weekend.
This is like the perfect video for me, I'm looking at these manifolds for when I get some new heads
I'd like to see a pull with the dual plane, open spacer and a radius blend done to the original carb mounting pad, both above, and into the runners. Would be interesting to see what the smoother transition would do to the figures.
Thank you for doing this video, much appreciated.
Great video Richard. Love seeing real world results with dyno numbers to back it up. I recently had a well known high dollar shop tell me plenum volume and intake design does nothing for a carburated engine and wanted to sell me a cookie cutter top end because they had 15 cars with all the same combo. Oh and they said carburators don't work either. Just had to laugh.
Plenum volume and intake design has a lot to do with how an engine behaves, otherwise you wouldn't have performance parts on the market.
Carbies also have their place, since they're so simple to fit as opposed to EFI.
But EFI does give you that flexibility to adjust each and every load cell to perfect the AFR's.
Lol. Reminds me from my friend, who claimed all the time that “carburetors don’t work” and from another dude which claimed that “you can’t adjust/tune a carburetor” omg I laughed so hard! 😂
Yet when I showed to my friend all kinds of carbureted turbo stuff, even from this channel, he still wanted to argue.
Then I “twisted from the rail” to him all the stuff from how carbs work to how they’re modified, and still he had to argue with me that efi is best in everything.
I said it’s better in some applications yes, but it’s not necessary!
I know from experience that old skool full iron 429 Ford with 6-71 blower makes more power with 2x4bbl carbs on top, than with 8-point port injection.
Just cause the blower spins “dry” compared to carbs where all the mixture goes through the blower,
where as you have two interesting events happening: as the blower itself makes the air/fuel mixture hot as compressing it,
the fuel in it and around the blower is making the blower and the mixture more density and cooler, than when compressing the air only.
And richer mixture in it cools intake temps, which equals with more power.
It showed on the dyno also,
in my examples car where the conversion was made.
Cause you know, you don’t give a shit for fuel economy anyways in that point when you have allmost 2000kg full size with 600hp big block with a blower on top. 😁
The biggest plus for efi is the easier cold starts. 😃
Wanted to see a video like this one for some time now thanks.
Awesome vid. Thanks for dyno proving all the things I've been telling people for years about intake science. However, in real world street application, the open spacer on the dual plane makes for some shitty idle quality in some cases. That said, I like how you mention adding the spacer at the track and then removing for the drive home.
My experience with a little 302 back in the 90's was that a four-hole space (swirl style) improved my throttle response and drivability. This was with a comp cams magnum 270, weiand dual plane intake and Carter 625. I've always assumed though that the benefit was all in having a larger plenum volume, so there was more air/fuel mix available immediately to fill the cylinder when I stomped on it.
Great video. My choice would the dual plane with carb spacers. Because you can tune it like a single plane for the strip, then go right back to dual plane goodness for the street.
Thanks for all the testing you do. Much appreciated. Would really like to see you get away from that 114 lsa. Those small blocks will always run better with a 110 lsa or lower. A 106 will wake that 347 up! thanks again richard.
This was pretty much the exact video I needed... I have an explorer 5.0 I'm getting ready to get back going again. I have some old skool 170 twisted wedge heads and I was trying to decide what cam to run. Looks like the stage 2 trick flow will work straight up and reuse my old air gap intake
I guess my 351w RPM air gap rock crawler is getting a 4 hole spacer for even more low end grunt. Neat video for sure!
The more of these comparisons I see you do, the more impressed I am with the RPM air gap. The newer (newer than the old performer) design really doesn’t give that much away to the Vic Jr and other single planes. If someone is going to drive their car on the street ... and maybe do some brackets or some road course track days ... I would probably recommend the dual plane these days.
Chris, how well would the air gap run out in the 7000-7300 range, not peak power but how much fall off would you expect? I understand so many variables involved. I'll be building a 302 based road race/track day engine that will have to touch 6800-7200 most laps.
Chest Rockwell ... that I don’t know. Might be an interesting test (hint hint Richard) I am merely thinking that RPM dual plane is a really good choice these days, Edelbrock really did their homework on it. If I was considering a carbureted application ... full disclosure, I probably wouldn’t ... but if I was, for street or track day or an amateur endurance racing car, I would probably look at the RPM air gap.
@@TheFarCobra I tend to agree with you on the RPM Air Gap, and yes would be interesting to see how adding a spacer, port work and such would help/hurt the Air Gap in the upper range where it begins to lose compared to the single plane manifolds. If I switch from the OEM and fully ported GT40 intake set up I will use a Holley Sniper/FiTech on top of a non fuel injected style manifold.
here's a video with some the questions we have being tried.
th-cam.com/video/yrDuXGmnqRw/w-d-xo.html
For me my go to intake setup is always a 1inch 4 hole phenolic spacer and a performer, or performer RPM style intake. That's the ideal street strip setup to me. The 4 hole helps provide the best booster signal (especially with lower vacuum due to a healthy street cam) to the carb, and also the material helps keep the carb COOL! For me, a street strip engine should NOT loose excessive low to mid range torque for small gains in top end power. That's unacceptable! Low end torque and midrange power makes street/strip engines fun on the street since on the street torque is king. Being a street/strip guy, having a good balance of power for street AND strip is important!
Back in the late '80s I had a Mopar 318 that responded very well to an open spacer on a Edelbrock dual plane intake. ...had to use the spacer because the intake was square bore and my carb was a spread bore(a built Thermoquad).
Richard I have a request. I’d love to see you build a Ford 260 small block!
Man I love these videos.....
Best of both worlds. My opinion
A fully ported dual plane with open spacer probably best combo for most apps.
On a smaller motor ( under 400 )
@@I_like_turtles_67 yes i had a rpm air gap on my 402w street car , all the good stuff AFR205 heads 58 cc and a good size cam 240s over 600 lift, air gap seem to bog it down even ported and divider cut. so i had my vic jr fully ported and added a open1 in spacer from wilson woke that puppy up big time, get rubber all 3 gears now, anything over 400 cubes and good size heads and cam use the vic or super vic,
@@deewiedman7384 This what I've seen all over the internet. I've never owned a vehicle with anything BUT a dual plane intake. This is my first 9.5 deck stroker motor. So I am looking forward to it.
@@deewiedman7384 This what I've seen all over the internet. I've never owned a vehicle with anything BUT a dual plane intake. This is my first 9.5 deck stroker motor. So I am looking forward to it.
Perfect video . thank you
Awesome vid Richard, intake manifold design is fascinating. I would love to see an annular booster vs. down leg booster test on a single plane. The annular booster is much more responsive in theory, so maybe the single plane would work better down low with an annular booster carb ? Heck, it would be cool to see that test on a dual plane too. 👍
@Jeff Kopis yes.. I have a 4 hole taperd 1" Wilson spacer and a new Trickflow single plane waiting in the wings, I'm just afraid to lose all my torque switching from my RPM dual plane and open 1" spacer. This is on a 448ci big block Mopar.
@Jeff Kopis I'ts just a weekend thrasher I take to the track occasionally. I probably wouldn't notice the 15 ft lbs of torque I lose through the midrange, but I almost never take it past 5,800 rpm either.. I know I would have to spin it higher to see a benefit with the single plane. I'm currently using a Holley 9380 850 dp which has annular boosters. I'm just curious if I could tune out the bulk of the potential midrange losses with a more responsive carb like the unit I'm running along with utilizing the taperd spacer which supposedly improves throttle response on a single plane application.
@Jeff Kopis a 66' Satellite.. I have the vids of a few track passes on here. At the time of those vids I was at 3,800 approximately. I'm scaling back with some fiberglass parts trying to hit 3,600 with me in it at the line.
I've always run 1 inch spacers on a good dual plane. And after watching your videos I want to try a bigger spacer
I'd like to see what idle vacuum and fuel consumption looks like on more of your tests.
Would Also like to see "typical DIY" porting / bowl clean up tested. Air flow and dyno. Set up typical street engine. 9.5:1, cam in the 220ish range, etc. Basically a motor that needs more flow
Lol, watching you on -Fastest cars- Netflix! Just noticed it was you!!!!
Would love to see the 347 with the Victor JR and Funnel Web with 1 -5/8 step to 1 3/4 to see if the HP would remain but the torque go up? Thank you for the test Richard and even more for SB Ford tests.
Since I no longer care about being First On Race Day and drivability rules my needs, dual plane with open spacer works for me.
This channel is pure gold ! Love it ! Richard , do you already tested the FRPP gt40x heads ? They are really horrible like all the bashing in the forums? Too much people claiming that they make the same power than iron gt40 heads ....
The X head makes more than the P or standard GT40 in my test
Thanks Richard. If happen another test with the X upload here in your channel... It would be awesome !
I choose the spacer love the info
My 6.4 Hemi Ram has a door that switches from long to short runners at 4500rpm. You can really feel and hear the difference when that manifold switches to short runners. I wish the aftermarket would pick up on this.
I really like how your different scenarios open up even more questions and other ideas in my mind. Have you put together a video where you compare different cfm carbs on the same engine to show how it affects the power curve? I really like the carb on an LS setup for classic cars and am curious if an LS3 with a cam like comp cams' 54-454-11 cam and spring job would benefit from a 750 cfm or 800 cfm carb or if it wouldn't make any difference. I would also love to see a shoot out between comparable Holley, Edelbrock, and Quadrajet carbs in the 750 or 800 CFM range! I am pretty sure you have some tests of that laying around in the vault somewhere. Either way thanks for edumacating us a little more each day!
Great videos..... Would love to see you do a 351 Windsor with Cleveland heads.....
I have a warmed over SBC 355 and I have a original Torker intake with a 2" transdapt spacer spreadbore adapter because I had a modded 800 q-jet but it had issues eventually so I stuck a temporary Eddy 600 on with same spacer and it runs like a champ and pulls right off the bottom hard with great throttle response with both carbs in a 4000lb 2wd pickup with 700r4 with stock converter back in temporarily and 232° cam , so there goes the keyboard experts insists that say an open pleanum will NOT work well on the street or any of my combination for that matter.
Would like to see the results of the single plane with the spacers
Always enjoy your video Rich. One question, did you change the tune (jetting) when changing the spacers? Please include this info in all videos. Thanks
Damn, put a music warning ⚠️ on this video.. I started taking my shirt off in the line at the bank. For those wondering, no singles were hurt in the making of this comment.
🤣🤣🤣
We, ok I, need a battle of the BOP 350’s!
I would like to see a 408 Windsor with great heads, healthy cam, and a fully ported super victor using Holley Sniper throttle body injection. Dyno as is, 1 inch open spacer, and then a 2 inch open spacer.
Love your content! Have you ever done a dyno comparison between the Ford 5.0 GT40 heads against aluminum heads like the Edelbrock RPM?
From what I have seen the Wilson intakes seldom help anything but top end power. Victor Jnr is a proven thing and the spacers usually gives them a bit more of a lift. Though seldom fit under the bonnet!
Dual plane open spacer is the way to go!
I run a 408w on the street. The best thing I ever did was swap the victor jr for a Weiand Stealth dual plane. Night and day difference on the street.
really? i had one ported and matched to my heads AFR205s seem to choke it. had my vic jr fully ported and woke that baby up. more air. feed it..
Video idea 💡, Cheapest way to make 500 hp with a 350 SBC!
Right on
Hi Richard, loving the sbf content. I am planning on building a motor for my 68 mustang using the Exploder junk yard as the base. Did those 11R heads go on the stock pistons? Thanks info.
yes they did on our motor
I would like to see what a 4 hole spacer does with the separation of the rear secondary holes cut. Making them merged together making one big secondary hole. The front primary holes remaing the same. I am thinking this might work well on the lower end of funnel web manifold.
Nice video!!! Got any flow numbers for those promax 210 heads?
This is the kind of stuff regular guys want to know.
Hey richard. Just want to let you know alot of us really respect and appreciate you expertise. I have a request, could you please investigate the infamous "block splitting" of the ford 302. I personally have a 302 block that was cast in 1968 or 1969 and i need to know what if anything i can do to prevent block failure.
The early block is stronger than a late hyd roller production block-something coming up on that
The biggest problem in those SP intakes is the unequal runner length and very short runners. Those kill bottom end torque. Also, in small rpm, there is not enough flow at the venturies, so the fuel doesn't vaporize efficiently, nor does it distribute evenly. I would argue, that two two-barrel carbs with same size venturies, running more symmetrical intake plenum could easily make more overall power.
I would definitely go for a dual plane with spacer and a NOS plate, still have plenty of torque at the street and throw some laughing gas on top at the track.
I would be VERY INTERESTED IN SEEING A BBF STOCK IRON HEAD TEST AS WELL ON THE 429 SOME OPEN CHAMBER HEADS AND CLOSED CHAMBER HEADS BIG PORT SMALL
The dual plane with open spacer looks like it provides best average torque and power. On good tires, you'd definitely miss those extra ~50 fiddlebees with the single plane.
Awesome test, I have an RPM Performer on my SBC, as someone who knows very little about carb tuning, I'd be interested in seeing what AFR's look like if you were to add an open spacer to a well tuned carb at the track. Would it need any adjustments to stay safe if you got lazy and left it on for the drive home or is simply a loss of low down power the only thing to worry about? Keep up the great work, stay safe!
if you add a spacer-it will need bigger jets usually (down low)-just like a single plane
@@richardholdener1727 Can you please test spacer height from 1/2" to 1" and up? I just watched a few vids of yours and in one of them you said that you gave an example of using the dual plane intake and just put on an open spacer at the track. But what would happen if you went with a taller spacer; if you repeated your tests of dual plane/single plane in takes with open and 4 hole spacers, but go up in height?
For a car primarily driven on the street I'll take a dual plane any day.
Using an Explorer 302 with original heads (GT40P) and Elderbrock Performer rpm intake, What is the most hp and torque? I am building a low budget Maverick cruiser. Not sure which cam I am going to buy. C-4 in it for now, but hoping to buy the parts needed for a 5-sp. Great tests you are doing.
What has been proven lately is the intake ports on the intake manifold if they do not really match the head and cause turbulence going into the port then power will be down , Edelbrocks RPM is better port matched then their race intakes which usually custom done
Tks!!
Here's a thought for some testing. Your favourate cams vs a cam selected using the 128 rule from David visard.
I always liked the weiend stealth over the rpm on a sbf - any test between the two?
No spacers used on the funnel web!?! What about open to funnel adapter/spacer? Or a straight 4 hole spacer on it? Really wanting to know this
Do a 1994-2000 3.8 Essex next!!!
my 5.2 dodge did the opposite, I had a dual plane air gap style intake and always have a stumble that i chased thru ignition, and carbs one day I took the spacer off and it has never had that stumble again.
what kinda gains wold you get with a dual plane intake by trimming down the centre wall to open up the chamber volume and using a 1', 2" or 3" spacer
I would like to see 1/4 mile differences one with more torque one with more hp
Gearing is going to be a big part of that. Take two 500hp engines, one that is making 500 at 5000 rpm and the other is making 500hp at 7500rpm. The first engine will be able to use much less gear, like a 3.08 to 3.73, the second one will be making considerably less torque so it will need more gear, like 4.10 or deeper and a big stall. The HP is the same but the torque is VERY different. Now make the first engine have a flat torque curve so its making 500ftlbs from 2000 to 5500rpm, and it will be faster with a 3.08 gear than the 7500rpm engine will be with everything else the same. The first engine will slow down with a 4.10 or deeper gear and a big stall, because you are wasting that thick smack of grunt its making at low RPM. The high RPM engine doesn't have any torque down low.. so it needs deep gears and a big stall so it doesn't spend any or very much time where its soft on torque.
I do Pontiac engines, this is common bench racing with 400s vs 455s and those engines getting stroked to 500ci. the 400 needs more gear, like 3.55-4.10, and stall than the 455 which likes 3.08-3.55, and 500ci will pull damn near any gear you put behind it from 2.41 to 3.55, then it will slow down because you're not using the torque to push the car as hard as you could be. Its fun running mid 11s in a heavy street car with a highway gear and a stock stall that gets 15-20mpg with mostly stock parts, with a bit of mix and match going on. A mid 11 second daily driver built for dirt cheap is super fun and reliable.
You see that all the time with little turbo motors, they are back-half heros.
That, and if you do alot of the tricks that guys do at the drag strip, alot of the time it kills hp on the dyno, but the car runs faster at the track.
A guy posted dyno numbers before and after upgraded springs and lost power like 15hp on the dyno, but he knocked like half a second off the 1/4 mile.
If you're doing it in the same car, the transmission will come into play way more than anything. Is it automatic, where does it stall, what tires does it have. My guesses when in the same car.
The first combo, The open spacer would be faster, regardless of transmission and tire unless it had slicks and an automatic with a stock converter.
The funnelweb would be faster if you had a stick car or a really loose converter or crappy tires. The cut in torque it might help a traction limited car while letting you really take advantage of a real gain in power.
On the 347 that's a crapshoot, the driver would have more of an effect than the intake.
Just get a nitromethane billet engine and have both.
I was just asking about spacers on your last video. You are a wealth of information. But I'm wondering about a spacer with a nitrous plate. If it's an open spacer on a dual plane intake should I mount the NOS plate over or under the spacer?
the nitrous plate already acts as a spacer-it changes the power curve before you add nitrous-placement with another open plate doesn't matter
@@richardholdener1727 Cool, thanks for the reply. You seem to really know your stuff, that's why I subbed to your channel. I LOVE this engine stuff!
If you have a 351w lying around could you do a Torker ll test on it? I know the Torker ll for 302s is junk but the one for the 351w looks like a low rise Vic Jr. Some guys have limited hood clearance.
Would like to try a correctly port mached dual plane!!!!! Might keep up with single plane on top end or close
Test spacer options (especially 4 hole) on the single plane intakes.
yea i have both open and 4 hole for my 402w street. i have a 1" open on it now. vic jr ported..
Looking for thoughts on my setup. 70 351C 4V closed chambers with Offenhauser Port-O-Sonic single plane with 1 inch tapered 4 hole Hamburger spacer under a QFT SS-750-AN carb. The engine is not built yet but came with the Offenhauser intake. I understand a dual plane would be ideal for basically a street car but just wanting to know that this combo won't perform any worse than stock.
NOT SURE I HAVE RUN THE PORTO
A good dual plane on the street all day long. Would like to see a comparison test between a high rise dual plane like the Edelbrock Air Gap vs a good lower rise dual plane. I think we would all love to have a great manifold like the air gap but often it just isn’t possible due to hood clearance issues. How much do we lose by having to use a low rise dual plane?
Cough weiand cough cough..
@@johnmurner2418On a SBF the Weiand Stealth seems to give more hood clearance than the Edelbrock because the carb pad is lower in the front. I am very happy with my Stealth on a 302. I run a ProComp knock-off Stealth on my 351w and it just barely fits under the stock hood with factory dual snorkel. No room for a spacer though.
Definitely the dual plane with a 1" spacer!
Small Victor 1540 horsepower on a 565 on a short dec. One kit. Chevy style
Aluminum head
I'm thinking the dual plane plus the open spacer and leave it at that.
an inflatable SPACER! filled with... inflatable spacer fluid! yeah! or an intake balloon thingy...
What is going on with the 429 and Richard you have to run that camshaft I have in my 429 I would love to know just what that camshaft is worth maybe a set of stainless shorty headers from Ebay they are like 80 bucks and a dual plane intake compared to stock
I'm surprised the dual plane which flows low 200 cfm can keep up to those big single planes.. In my mind I figured the dual plane would have been down quiet a bit since the heads are good for mid to high 200cfm, and the differences in cross section. Dyno testing opens your eyes 😮
The speedmaster dual plane on the 302 needs to be tossed in the scrap pile for a stealth or airgap. Theres no way a spacer should net that much power on a 302 that runs to 6200.
Wanted to see the 4 hole on the funnelweb.
Doesn't Koenigsegg's Free Valve tech give you that best of both worlds scenario. It's super complicated and you probably need a PhD in computer science to trouble shoot it but it is pretty darn cool. They are getting 600hp out of a 2.0L three cylinder twin turbo engine which truly brings home EVERYTHING IS BETTER WITH BOOST. Now I need to get that same hp/L out of the 6.7L in my truck :)
Race only = single plane intake.
Street or street/strip application = dual plane and maybe add a spacer for racing.
Nothing really new here, but confirmation of what was believed to be good combinations.
If you have a big stroker a dual plane couldnt keep up with the head a 408 needs to spin 6500
But in a 302 even a hot street 302 dual plane and a 650 vacuum secondary
Hi have you ever used a tapered spacer and a dual plane intake upside down does it work thank you
For variable(while the car is being driven) runner length, search up "the silver bullet rotary dyno" from Fullboost. Pretty simple setup, but no comparison to static runner lengths. Any chance we could see this setup replicated and tested here?
I'm currently running a performer intake on my mildly built 318 with a 1" 4 hole spacer plate . it does good but I going to switch to a open spacer plate . you ran a 1/2 inch open plate but what would a 1" open plate do🤔. Or take a 1" 4 hole plate and cut out the middle dividers to mimic the aluminum intakes that come from the factory with the air gap in the divider? I have seen good results from when they take an Indy style single plane intake with the square open top and they drop on a 1/2" or a 1" spacer plate with a 4 leave clover syle pattern . basiclly a square hole with the corners taken out a 1" hole in place of a sharpe corner . I dont know the proper name of the spacer plate of the cover pattern. What would a 4 hole plate do on a single plane?
good luck
So... I wonder if the open spacer would have picked up as much if it was under a 750. Surely if the carb is reaching the top of it's airflow potential an open spacer will produce more of a power gain than if used with a carb that was generously oversized to start with? Another interesting test would be a divided spacer vs open vs 4 hole on a good dual plane, divided opening up the plenum volume and maybe the distribution on each half of the carb, without offering all 4 barrels to each cylinder.
the carb size is not why the spacer improved power