Does Cutting Down The Divider On A Dual Plane Intake Manifold Help

I show the horsepower change with cutting down the divider on a dual plane intake manifold and share which carb spacer worked best.

[@txredline203]

Eric you provide fact based information. I appreciate what you are doing. Keep up the great work.

[@RyanMcIntyre]

I live and die by the metrics. Information like this is the most valuable and it doesn’t matter whom it comes from - facts are facts and are repeatable.

[@shawnwalsh5430]

Folks, information is priceless. Spending money on books is cheap insurance if you're a novice or a professional..

[@ThomasELeClair]

,,,,,,,,,,,,,,,,True ,,,,,,,,,,,I can't rely on my memory.....Too much news comin in,,,,I write down everything into a journal ; I value my books as much as my machine shop......................

[@yarrdayarrdayarrda]

Keep in mind this is a fairly high RPM test. For those building street engines, 2500 to 4000 is where you're going to be most of the time, so a few HP upstairs is great, but you want torque and a happy engine when it's turning 2500 to 3500 driving down the road at part throttle. I've witnessed open spacers making 5 to 15 HP extra while running the dyno, and it's good for bragging rights, it will always hurt torque numbers down low, and will negatively effect drivability.

[@WeingartnerRacing]

Chances are if you are at those rpm’s you are not wide open throttle.

[@grahamgeiger3206]

Maybe in a race car but if you have a heavy street rig or pickup and especially with a wide ratio manual transmission you do see full throttle quiet often around 2500-3k rpm

[@tomstrum6259]

Thx Eric for showing this....Like forever, We've been Told Cutting down the Divider Favored Top Rpm......Thx for showing what really happens.....

[@angelsanchez3074]

You always provide us with the correct information. And all the graphs to prove the results. Good job keep up the good work.

[@WeingartnerRacing]

Thanks and keep watching

[@angelsanchez3074]

@@WeingartnerRacing I have a 302 SBF Mild build with a 4 hole 1 inch spacer. And I plan to install a open 1 inch spacer as in your graph it shows more power throughout the whole RPM range. Can never have enough power. But should I take down the center or will it perform just as well with the center still intact?

[@immanutt4442]

Absolutely without a doubt this tutorial is the most comprehensive in depth cut through the chase proven intake spacer data log ever

[@WeingartnerRacing]

Thanks,

[@charlieperry26]

I love the honesty and the humble attitude you give... the content and information from all your videos is awesome. Thanks for taking the time to share...

[@stevenbean9706]

I love how your dyno room looks like a cozy room ! id cut the divider down just to enable running a 3 barrel

[@aubreycollom7201]

I'm not a chevy guy, but I really dig your videos. That's a lot of research at your expense. Thank you for the great information!

[@WeingartnerRacing]

Thanks for watching what is your brand of choice?

[@peskypeet]

👍 Doing good things Mr Weingartner. Your testing and information is appreciated.

[@WeingartnerRacing]

No problem

[@peskypeet]

@@WeingartnerRacing Hey, just wonderin if you'll try different sizes of open pacers on any of the dual planes. 1/2 - 3/4 - maybe some over 1inch? Or maybe try something strange like an open with a 4 hole at the top. It'll probably take more time than what it's worth and be very subjective to the manifold being run due to plenum and port differences.

[@ThomasELeClair]

@@peskypeet ...................I have and like the combo using a tan colored phenolic 4-hole on top off an open one inch spacer.....may be hood clearance problems ........wtf....

[@hangfire6368]

Nice test. My uncle bought the AFR for a 406 build in a 65 C10. I shared the videos with him and mentioned opting for the open spacer for some extra power. No way I would have know this info without your testing.

[@BillyWilliams-d2e]

Thanks for all your help. Finding the perfect gen 1 small block, for my 1968 Nova. Amazing Horsepower 👏

[@JohnDoe-ud2cc]

The afr is what I would go with. That huge bottom end gain is worth the few hp loss on the top end.

[@donnelhuddleston2478]

It used to be worth 15 to 25 HP on a Small block Chevy in the 70's & 80's, it's probably worth more today with engine builders making so much more power than they did back in the day, yes its such a popular mod that the air gap Manifold came out.

[@danmyers9372]

The Edelbrock Performer RPM air gap has slightly longer runners than the non air gap Performer in addition to the lowered IAC benefits of the air gap. I have often heard engine builders say that cutting down the divider on a dual plane manifold can slightly improve cylinder to cylinder distribution issues inherent in the manifold design. The only way to accurately verify the AFR in each cylinder is through a temp sensor in each exhaust header. A single sensor in each collector gives an average of the AFR’s in that bank. The individual AFR’s can vary significantly, sometimes as much as 3 points! While the overall AF may be 12.5 you could easily have one or more cylinders at 15.0+.

[@Sludge73]

No Superman denial. 😂 Great video, just what I've been waiting for! Thanks for putting in the time!

[@duke5171]

Interesting to see varying results from lowering the dividing wall. Ben Alameda did a video on his observations with a SBF netting a Loss of 27hp from 556hp after it was lowered.

[@stevelaw2000]

But at what rpm? Did it gain in the upper rpm range?

[@ivo3396]

Great work Eric! I believe Jay Brown did a similar study/comparison for FE Fords. We all appreciate your hard work and effort to provide us with beneficial data/information!

[@WeingartnerRacing]

Thanks for watching.

[@kramrollin69]

You know, it is the year 2023, and yes your video is great, but back in the ancient times, we use to have strange things called books and magazines. Back in the early 1900 and 70s, Chrysler engineers wrote the Direct Connection manuals on go fast Mopars. The recommended Small Block race manifold, was the Edelbrock LD340 dual plane for Super Stock and all performance. Back then they ran 10s in SS.....early 1900 and 70s remember. The Race Modification to the LD340.....was to cut down the divider to 3/8" off the floor. In other words what you have done. They dynoed all their mods. It made to best power for the cars at the time. Isnt it amazing that you can still provide this info to newbies, that was already known by us all 50 years ago. In fairness, I bought my DC manuals in the early 80s....so yes, I knew of this mod since then....and yes I have an LD340.😄 Keep the info coming.......as nobody reads book anymore, or looks up already proven info....Perhaps more newbies should be asking the oldbies how its done..............

[@sjaywjayw70]

I have a dual plane with a heat sink 3/8 spacer. I cut the center out of that.

[@c.n.9074]

Very nice work here Eric.....and a lot of it!! When I see and read info like this I'm reminded of the IROC racing series. Their professional engine builders with the best most modern equipment struggled to get all the engines built completely the same to get the engines to perform equally . They always seemed to end up with one that was a slug and one that would run circles around the rest. It is certainly not feasible but a test of three differently built engines testing the manifolds and the performance differences would be interesting but a budget the size of GM would be necessary for that type of testing. My point is if people really want to know what is for their combination, they need to do what you always do and that is , test, test, test.

[@davenorman8251]

Thanks for doing this series of videos Eric I like the no BS approach..In a nut shell for all the street hacks like me Edelbrock performer for the win

[@WeingartnerRacing]

Thanks for watching.

[@donaldhalls2189]

Once again very informative, information, very well presented, thanks for sharing, all the best to you and your loved ones

[@shawnlibby4762]

But different compression different size V8 motors that they do go on will play a role in which intake setup works best on what... Just my...2 cents..lol.. but thanks this is awesome information..... You're good at what you do... Brother

[@jasonhumphry5836]

Awesome video just what I was looking for as I'm planning the same mods as always peace and much respect to you ✌️ Jason

[@quick455]

Peak numbers are great but I've found the drivability and tuning is far easier on the dual plane with the divider notched, or an open spacer added if there's clearance under the hood. The science says it smooths out the pulses since the share part of a common plenum now, I just know I get an easier to dial in engine with better road manners with a carb and especially when going to a setup like a Holley Sniper that needs a good clean vacuum signal. The original gen Snipers suffered from this greatly with the MAP port placements but I guess they have made improvements to that vacuum channel under them. I still like doing it just to help the ECU to get a nice clean constant signal as opposed to reading it off 2 separate banks of 4.

[@177SCmaro]

With small runners and ports people often assume it will make all the torque not realizing the torque is a function of volumetric efficiency not air velocity. It's possible for a larger runner and port to make more torque with somewhat less velocity just by filling the cylinder more effectively.

[@biggie9817]

I've always read / heard that when cutting down a divider on a dual plane intake you should consider taking 1/2" to 1" so your Edelbrock Performer RPM with the 1 " spacer kinds supports that school of thought. Like you stated the spacer effectively cuts down the divider down an inch.

[@shortchange26]

I would think manufacturers such as Weiand, Edelbrock and whoever else is out there would essentially know what works best. I mean look at the test equipment, flow benches and all the other high dollar test equipment they have for R@D.

[@ThomasELeClair]

,,,,Saw that Q-jet manifold on the floor scheduled for a future test comparison,,,,,,,,Hope to see the outcomes soon,,,,Thanks Eric......

[@WeingartnerRacing]

This was over a year ago. I couldn’t test it because it wouldn’t seal.

[@EliminatorPerformance]

For a test like this on a dual plane manifold (and this is just my opinion) I sure would've liked to have seen the dyno graph from 1500rpm and up. At the end of the day, most guys running a dual plane have a street, or a street/strip engine build. I found this video because I was curious about the divider in my Edelbrock intake, and if there would be beneficial gains up top by removing the divider (bringing it slightly closer to a hybrid dual/single plane) without sacrificing too much bottom end. This and Ben Alameda's video answered my questions.

[@Wei55_und-stolz]

Sooo after seeing this I will leave the plenum stock on the Edelbrock Performer in my street machine.

[@daledavies2334]

Well, it depends. If you use an open spacer, that is like cutting a crossover in the divider. If you have a hood clearance issue and a spacer would push the air filter assembly into the hood, cutting the plenum divider is the answer.

[@cliftonparker7817]

Cut the divider to same dimensions that edelbrock already cuts the divider on some of their intakes and run a 1/2 inch open spacer Perfection

[@WeingartnerRacing]

Maybe

[@johnkufeldt3564]

Thanks, I apprciate your "just the facts maam" attitude. Liked, subbed(awhile ago). Cheers from Calgary.

[@WeingartnerRacing]

Thanks for watching.

[@MoparMan-ff8fb]

I did a mod for my air gap intake for my mopar mildly built 318 . I did a 1" 4 hole spacer but I cut out the divider between the 2 secondaries and the 2 primeries . 1 " long was the cut out helped alot even though I dont have the funds or location for a dyno test

[@AndyR1982]

Just grins, it would be neat to see a factory iron manifold cut like an Edelbrock performer. Then milled like an rpm air gap to see how it compares to an air gap. Factory mods like a super stock class competitor would get from "tricking out" factory stuff.

[@The340king]

What I found with some limited testing with the 2701,having some communication between halves didn't change HP, but it leveled out the EGT'S. So, we kept the open gasket to get better distribution.

[@donbrutcher4501]

nice work

[@colinlawrence2186]

Awesome video thanks you for sharing this with me i love this kind of information Take care stay safe and may God bless you always 🙋🏻‍♂️🇬🇧

[@WeingartnerRacing]

Thank you.

[@tomthomas9910]

Seen a Edelbrock dual-plane manifold that was notched out about 3/4 deep x 2 in length along the divider " at this racers shop " ? Always wondered if you'd get the vest of both worlds low end and some on the top"

[@danawilkes8322]

For street use. The test should show 2,500 rpm on up. Not 4,500 rpm or more as a starting point.

[@gasparsperformance9841]

I randomly came across your channel and I’m glad I did. I definitely like learning about information like this. Keep up the work!!

[@WeingartnerRacing]

Thanks please keep watching.

[@rossgirdeen3247]

More Cleveland videos love the ford stuff

[@WeingartnerRacing]

It has to come into the shop to make a video.

[@rossgirdeen3247]

Ok cool really enjoy the Ford stuff especially the Cleveland!

[@generalsixty2133]

I recently dyno'd my sbc 388 boat engine mild 230 ish 113 LSA cam 10.5 cr with Air Gap intake on old-school Eddie Victor race heads I had laying around. The tall head ports almost don't cover the Air Gap intake. It made the best power and most stable air/fuel ratio at 5000 with an 1-3/4" open spacer with stock divider. It was better than the 1" open spacer we tested.

[@jeremiah5928]

113 lsa sounds like too much for your combo i'd tighten up the lsa to optimize performance use David vizard's 128 formula for sbc

[@generalsixty2133]

@@jeremiah5928 This cam grind was tested years ago for mild street 383 combos. Jet boats are hard on engines so making 473 torque at 4800 rpm and 475 hp at 5400 should be ok. Less fumes with the wider Lsa. From what I heard the 113 cam is better to tune the carb with better vacuum. This cam was advanced 2* if I remember.

[@bigandlittlecountry]

@@jeremiah5928 you dont want exhaust reversion, so most marine cams arent that tight due to the water in the exhaust.

[@markbuskens6070]

Very interesting,had a 408 smallblock Chevy with highly modified iron Vortec heads and a RPM Airgap made for Vortec heads port matched and it was brutally fast.750 mighty Demon no spacer or modified divider.RPM Airgap a super street and race manifold

[@michaelmaher4328]

Great information Eric, thanks.

[@WeingartnerRacing]

Thanks for watching.

[@fppro1679]

Interesting information. The fact that there were four commercials in it was irritating. Given the numbers, you really wonder if you can feel the difference is in horsepower unless you went to the strip and even then with those minor differences in horsepower if it would make a difference...?

[@travissizemore116]

Whens the Ford head video coming? Your videos are very informative, Thanks for video's!

[@WeingartnerRacing]

Its recorded I just need to put it out.

[@vehdynam]

Great information! Many thanks for taking the time to do this, much appreciated.

[@PeggyParrow]

Eric, try this, get a 2 inch 4 hole spacer and cut out the divider almost completely on the passenger side, no other mods. Install it on a 400 sbc with big heads, roller cam. And an airgap intake ! My 400 w..sportmans 200, Fts. 654 roller, 251..258 ..110 and jetted right gained 20 hp ,dyno man was stunned, engine sounded better,,why, I think it more equalized the plenum? I used air gap to run on the street for torque, it was 500 ftlbs

[@obbyjep7597]

Thanks for sharing this very useful information

[@autonomous_collective]

Start your Dyno pulls at 2000rpm for graphs....

[@WeingartnerRacing]

That would be pointless

[@jesseparadis6141]

Not for us street guys with 2000 stalls 😂 sorry we all don't run 3500 to 4000 stalls 😂

[@richardyounker6128]

i did that differently. i kept the divider flush to the base plate of the carb and had a opening about an inch the width of the divider on the floor of the manifold.

[@richardyounker6128]

more info. i was using an open plenum manifold with about 3.5" carb base to manifold floor. my spacer was about .750" and a slot to install a plate to span th carb opening. i left an openin about an inh at the bottom edge of the plate and floor. i ran the plate front to back but it could be run left to right. i hope you test it.

[@straighttimestirrups]

I can’t recall (I think it was a Weiand) which single plane manifold I had on my 355 SBC. One of the magazines in the late 80’s/early 90’s installed a separator plate vertically in the center of the plenum to boost torque. I made one and installed it and it seemed to work well. Have you tried doing a test on the Dyno doing a similar mod? It would be interesting to test this out and then start cutting the spacer down 1/4” at a time.

[@scottloutner5253]

Engine masters showed real gains on dynamics with divider cut out.

[@Just1Spark]

5:50 also possibly consider, the oil being hotter making it thinner reduces ring seal, which may help contribute to the drop in hp at higher rpm.

[@oscarpuente2029]

outstanding. information!

[@terrycarter8929]

If you want to keep the oil and coolant Temps constant you could use an external oil cooler cooled by the coolant. Thermostat controlled to help control it.

[@pacman3908]

Great info Eric much appreciated sir

[@WeingartnerRacing]

Very welcome

[@lte008]

Interesting. What about an intake with the divider left in it with a 1" divided spacer?

[@WeingartnerRacing]

I think it is a good idea

[@drt6680]

Great video! My question, has anyome run a uncut performer rpm with a super sucker spacer installed upside down???

[@robertkeime4907]

Great video

[@WeingartnerRacing]

Thanks for watching it does help the channel.

[@dybamx]

wish you would have tested without the spacer. IE: if you don't have the hood clearance, can you gain by cutting down the divider instead of running a spacer?

[@facemobb3288]

on pontiacs they found it worked best to only delete the divider under the secondaries on the performer rpm

[@Silver69vette]

Great video. Thanks. Have you tested the 2701 with a Holley Sniper EFI? Some folks say the divider should be cut and some say it’s not necessary. Looking for really data before cutting mine. Thanks in advance for your input.

[@timothyarnott3584]

Hey Eric, Tim here.....I havent gotten to the results yet, but the EPS works great for 350 hp motor, i bet it works bad on a 11:1 406, with a big cam.......just sayin certain manifolds are tailored to the application.......my shop has used a # of EPS'S on 400 hp or lower motors and have had OUTSTANDING results.......great throttle response, great drivability, but at 5200/5500 RPM ur done.....just sayin an EPS has no place in the test.....its designed for smaller motors, less compression and MUCH less hp.......ok, gotta go back to the vid....

[@WeingartnerRacing]

I wasn't knocking the EPS. It actually did really well. It is not made for this motor but it was neat to see what it did.

[@timothyarnott3584]

@@WeingartnerRacing i agree, and i wasnt tryin to poke at you, i was suprised it did what it did on the mule.....TY fer the response.......gotta get to ur store, my t-shirt needs a replacement haha...PEACE to you sir!!

[@dietervaloczky6051]

I found the cloverleaf to be great with throttle response and upper hp without affecting drivability, nobody ever tries them and info is n/a

[@72blazer48]

Would like lower RPM data, 2000 and up.

[@jesseparadis6141]

Right eps would be in the lead

[@darrendelaney8161]

more silliness, whats with all over 4k numbers? am i to assume differences are not worth mentioning below that? spiners spinning and calling that power. oh eff durability or duty cycle thats fer neeerrrdddsss.

[@bacn5]

Thanks for doing these comparisons they are so interesting and exactly the kind of information technical gear heads like me are looking for... Since you are doing dual planes, it would be nice to see the results/ comparison of the newish Edelbrock Dual Quad Air Gap RPM with 1000+ CFM of carburetors on it. I know other dyno test have indicated that a single carb and single plane are better, but those same people also claim you only need 750CFM on a SBC and should never need more than 850 CFM on a 406... Personally I believe the Dual Quad AirGap would be the best all around set up for your 406 in a Pro touring street car or a road course car. If you are able to do it, please also comment on the hidden partial plenum divider on the passenger bank which I’m guessing they added to further spread out the torque curve.

[@WeingartnerRacing]

I don't have two good carbs to do dual carb set ups.

[@josephbacarella2242]

I have a complete new never run set up I plan on running in the future I could let you borrow. I even have a jet/ metering rod kit for each carb. Let me know if you think it’s worth the dyno time.

[@josephbacarella2242]

In fact I have an older non-air gap Edlebrook dual quad intake you could also use to compare air gap vrs non-air gap if you wanted. I also have a Torker II which might round out your single plane testing for people with limited hood clearance.

[@ldnwholesale8552]

Most road course cars are under 366. 6 litre. And I have not seen a roadrace car ever with duel 4s. Maybe some historics but even then it would be looks. 750cfm is generally best on a 6500 rpm 355 engine. 7000 rpm maybe an 850 for top end power. For a tight course with slow corners the 750 will be better. All this on a single plane. Dual plane is generally nicer for a strong street car. Airgap RPM seem to be the best I have seen. And fits under most bonnets without a spacer.

[@GaryH-pw9cm]

I tried an Edelbrock two plane 302 manifold with an 850 CFM carb on a 427 W using Price Motor Sport adaptors. Seemed to make more low end torque but less upper end HP. May be Eric could try this and see what happens.

[@WesternReloader]

This test/results, I can corroborate, for dual plane with 1” open spacer (mines wood but doesn’t matter) *Weiand Street Warrior, not Dyno’d, also on a mild 10.5:1 sbf 331, but seat of pants was obviously better vs. 4 hole spacer

[@WesternReloader]

*stock divider better than milled w/ open spacer… my guess is velocity of air = better mixture = better burn up top?

[@WesternReloader]

@@lollipop84858 compliments of UTG

[@RonaldLewis-py6yt]

I had a old performer off idle to 5500 i cutt it down now im going to get the Air Gap for my 383 buuld!!

[@bassettraceengines]

Great info. If i remember correctly the EPS was designed specifically for a 350 cid engine.

[@MrMechanicandy]

Seems like motor difference and or your dual plane center cut down for Richard holder did both and the 4 hole did better than open spacer but his spacer wasn’t open hole tapered spacer .

[@jcnpresser]

Man your putting in the hours! Thanks!

[@johnsheetz6639]

What I've seen it helps. Especially for the fuel injection guys.

[@bobstitzenberger1834]

I really enjoyed this episode. Next time you dyno a manifold with exhaust crossover, could you dynonit with a shim closing the crossover off, then yank the shims so we can see if it really makes a difference. I grew up thinking it mattered, and I'm pretty sure now that it doesn't. The air isn't in the manifold long enough to heat up, is my hypothesis. Maybe you could make your head flow numbers and dyno data available for a subscription ?

[@WeingartnerRacing]

There is exhaust crossover in the heads.

[@bobstitzenberger1834]

@WeingartnerRacing , I just want to know how much difference plugging the crossover makes. I've gone to a bit of effort in my life plugging crossovers, and now that I'm old, I think it was a probably waste of time.

[@yarrdayarrdayarrda]

@@bobstitzenberger1834 Crossover will help during warm up (not to the extent of the engine having a functioning heat riser valve which normally get tossed for headers) but has minimal effect once the engine has been running long enough for the oil temperature to stabilize and the entire intake is 200 degrees.

[@teamgonzo9289]

Enjoyed this video very much!!! 👍 And you're right it's not what I thought either. So I got a question........ Are these double humps ever considered to be called bow ties. Because I noticed the 202 numbers???

[@gearhead7896]

There's a guy on KZbin that milled the divider with a router. lol It worked and looked great.

[@gearhead7896]

@@lollipop84858 I didn't say it wouldn't work. It's just unconventional. When I think about doing this job I automatically think about it in a mill. Aluminum machines easy, so the router works great.

[@EsmondPerformanceEngines]

Eps was designed to maximize torque around 3500rpm

[@innovate.integrate.transfo6169]

Great information... not sure I would call close to 5,000 RPM "down low" with a 6500 limit though :-) Just sayin'

[@jesseparadis6141]

Right 😂

[@HDUG7up]

so... the best is edelbrock rpm without cutting the divider? damn bro

[@alexlandsberger1423]

I had an eps on a 283 it's been my favorite intake for me so far, I got it on sale so it was only $125

[@WeingartnerRacing]

They are reasonably priced.

[@johnzuggster375]

Thanks!

[@joearokis8265]

Curious how much they weigh, that AFR looks heavy. Thanks for the great content.

[@michaelmoore6186]

I'd like to see a. 1/2" 4 hole spacer between the carb and 4 hole taper spacer and a 1/2" open spacer between the manifold and spacer and tgen go up to a 1" 4 hole and open. 😀

[@WeingartnerRacing]

I did test 4hole tapered and open 1 inch spacer.

[@prettyvacant2729]

Be interesting to see if the airgap is better than the RPM.

[@WeingartnerRacing]

I might try it someday.

[@sammcbride2464]

The open spacer eliminates the need to grind down the cross plane.

[@DanielBODell]

I cut down duel plain intakes back in the 70s,one of my secrets that I didn’t share!!

[@kobra289]

The brand of engine matters too. Ben Alameda did dyno testing with different Ford dual planes and concluded that cutting out the divider hurt the horsepower.

[@WeingartnerRacing]

It may be how the runners are paired.

[@peskypeet]

How big of an engine was that, what heads, what cam? I think all of that has a potential to change the outcome.

[@patrickwendling6759]

Thank you for your knowledge and videos USA 🇺🇸 USA 🇺🇸 USA 🇺🇸

[@WeingartnerRacing]

Thanks for watching!

[@jesseparadis6141]

Eps looks like the best for a street

[@jeffbuckleydisciple2013]

Great video bro

[@hankclingingsmith8707]

Most of you intake info is validated on dyno sessions and test fo 20 years. All street motors hot street strip performance rpm is ticket. Watch any engine builder who builds power. Thanks

[@travisbeavers1203]

Would you think cutting the divider would help or hurt under boost?

[@WeingartnerRacing]

help

[@travisbeavers1203]

Thanks man love your stuff

[@goratgo1970]

Need to cut divider for airgap BBC dualplane (streetcar) using Fitech EFI with single Tstorm, but unsure on spacer?

[@archivegarage7638]

Eric, would you consider doing a comparison video between "Mule 250": 2701 EPS w/ 1" Open (watch at 9:09) and "Mule 249": 2701 EPS NO SPACER (watch at 13:06)? Seems like the 1" open did the opposite on the 2701 EPS vs the AFR 4812 runs "Mule 225": 4-hole vs "Mule 226": 1" open.

[@WeingartnerRacing]

I only used a 1 inch open spacer when I tested the 2701. None got tested without a spacer.

[@archivegarage7638]

@@WeingartnerRacing Thanks for the reply. Any idea the difference in Mule 250 vs 249? EPS Mule 249 run matched the AFR Mule 226 all the way to ~5,800

[@DDDD-of3hv]

i wish the performer rpm on my pontiac was a true square bore and not spread/square, i've often wonder about turbulence and air flow when using a standard 4150 vs spreadbore on these dual plane dual carb pattern intakes.... any thoughts? i only have it port matched, not sure if there are any "porting/tricks" that could enhance it, i would be interested i haven't used a spacer, other than the very small spacer for using the 4150 (its a small plate edelbrock sells to ensure sealing) i may try some spacers, but they can start adding up, as i've seen a spacer with divider for dual planes, and also see the open and 4 hole ones, clearance might be a bigger issue if i went that route too i have thought about just going with the torker II to get a little more clearance since its shorter but has square bore pattern

[@davelowets]

It's ALWAYS worked for me...

[@fordguy8613]

Would this same test be similar if those manifolds were efi?