What Carb Spacer???

benno440 · Jul 14, 2013

Guys,

i have an edelbrock ch28 intake, which is a dual quad, dual plane, open plenum intake.
with 2 afb edelbrock 500 cfm carbs ( 4 butterflies)

i need 2 x 2" carb spacers.

what type should i be using???

*4 hole spacer?
*dual plane spacer?
*multi tapered spacer?
*open spacer?

the open spacer and multi spacer will let fuel/air into both sides and the purpose of the dual plane will be gone, thus why i am confused on what type to use?

also the gaskets supplied with the afb carbs are an open gasket so even though the carbs are tightened down they probably still sit slightly off the intake in the middle and deeming the dual plane useless as well, am i right???

any advice is appreciated

Propwash · Jul 14, 2013

A 4 hole is supposed to improve idle, throttle response and add low end torque. An open adds torque and HP, but does so by pushing TQ/HP peak to a higher RPM. The Dual Plane is like an open (adding to your plenum space), besides the fact it's split to accommodate a dual plane manifold set up. Multi-tapered are a MFG's efforts to try to grab the best of both worlds of open vs. 4 hole, but are usually pretty pricey. My 2 cents

Meep-Meep · Jul 15, 2013

2" might not be necessary. I'm thinking 1/2" to 1" open hole to see if that improves anything. The CH28 is a dual plane divided plenum intake, which means it's not an open plenum design. Yes, that little space in the middle is like adding a tiny spacer but I doubt there is anything happening from that. I'm suggesting the spacers because your monster cubed and cammed engine might like to see both sides of the carbs at idle. This will allow all the cylinders to receive fuel from both sides of the carb rather than only 4 cylinders receiving fuel from one side of the carb.

benno440 · Jul 15, 2013

thanks meep , was also told to go a open by damon Kuhn as he also said with a big motor you will want more air/fuel going in from both sides of carb. my main reasoning with a 2' was the reverse cowl hood I put on will allow me to lift my massive hemi air cleaner into the cowl to receive the cold air at the base of the windscreen while sealing the base to the bottom of the hood and blocking off all hot air.

prop, your info was also helpful but as firther researching recommends that a 4 hole is better for a smaller engine. I will post my results when I get them on.

nomax · Jul 15, 2013

Just my opinion,
I'd go with what damon suggested first.
Man builds killer carbs and combos

Did he know your running a cowl hood?

benno440 · Jul 15, 2013

thanks nomax, yeh I told him.
heres a pic

Cranky · Jul 15, 2013

How thick is your open gasket? If it's not very thick, it probably won't have much effect. Did you mention that to Damon? I know him personally and the guy just amazes me....but maybe I'm easily amazed?

What kind of gas are you running? When I went to Europe in the early 70's, it really made me think about how bad things could get in the states and well, I think we're getting there but what's it like there now? Man, their gas sucked AND it stank! How anyone can have a good running car in Germany was....amazing.

Propwash · Jul 15, 2013

prop, your info was also helpful but as firther researching recommends that a 4 hole is better for a smaller engine. I will post my results when I get them on.

No sweat benno....Definitely wouldn't consider your engine a "small motor" LOL I have a 4 hole on my 512, but it's only 1/4" thick. Basically using it as an insulator to keep the engine heat out of the carb. Any taller than that and my engine would be making it's own hood scoop. Hope to see that beautiful Charger running 100% here soon. Best of luck.

Meep-Meep · Jul 15, 2013

Then throw a 2" open spacer if you have the room. You still might have to tweak the low speed circuit a bit richer as I suggested earlier, but the spacer should help without drilling anything. And hopefully you won't have to do anything else. By the way, if you wanted to make your newer Eddy 500's into 625's (or are they actually 600's now?) all you need to do is change the primary booster venturies. You might also get a slightly richer idle feed / low speed circuit restrictor out of the deal. Just for fun contact Edelbrock and see if they will sell you just the venturi clusters. If I had extras I'd send them over.

67 coronet · Jul 15, 2013

i am very interested to see how this turns out benno.hope you dont loose any noticable bottom end torque with that tall of an open spacer.its kinda like you are creating a mini tunnel ram,but if your motor likes it,then so be it.

benno440 · Jul 15, 2013

thanks guys, yeh like damon said this dual quad intake is too small for this engine so a mssive open hole is a massive benefit as it is increasing it plenum volume to more on where it needs to be.

gas question; highest pump gas we got here is 98 octane which is the equivalent of your 95-96 i think, we can get any and all race fuels but at the pump we can buy 92, 95 & 98 octane

- - - Updated - - -

thats interesting, i thought the bigger cfm was the size of the carb ports, did not know this, it might be the way to go. they are still 500's at the moment.

- - - Updated - - -

i got a car show this saturday so get my bonnet finished and get to some tuning on friday, hopefully i can nut it out, i have had the car running really good except for the run on, which i think was because i was doing my timing and tuning when the engine was not completely operating temp and the front carb was slightly open due to bad lineup of carb linkage.

want to say one more thing, if anyone is ever interested in doing some custom suspension like the magnumforce i have in my ride, all i can say is WOW, the car handles and rides better than my mates new mazda (IMO)

What Carb Spacer???

benno440

Well-Known Member

Propwash

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Meep-Meep

дворянин

benno440

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nomax

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benno440

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Cranky

Banned Henchman #27

Propwash

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Meep-Meep

дворянин

67 coronet

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benno440

Well-Known Member

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