Holley Phenolic Spacer/Dual Plane Manifold

[84stanggt-top]

Not sure if my theory is sound or not, but i'm thinking of adding a 1 inch or more phenolic spacer for my carb, four port (since I have a dual plane intake), my reasons are:

1. Cooler carb temp, but I have an air gap intake already? Will it matter much (or matter at all since a normal gasket is 1/4 think anyhow?)
2. maybe increase low rpm velocity? I think I'm reaching here...thinking maybe more straight line momentimum (sp I know..jus me bein cheeky) before it hits the intake.

I'll have extra room with my raised hood, and was hoping it might help with the 750 double pumper I got (i know too big, but still plan for a stroker ot 351 block build later) with respect to throttle response sub 3000rpm.

Seriously thinking of dropping to to a 600 or 650 CFM, cause I may have to live with my 91 roller for longer than a few years.

Thoughts?

[Pro SC]

Its been a while since i have played with carbs, but if i remember correctly, using the spacer will effectively move the power band up and you lose some bottem end power just like putting a spacer between the upper and lower on an efi intake. I would go for the smaller carb for drivability, as you can always sell it when the time comes to upgrade.

[84stanggt-top]

Thanks Mark, couldn't remember which way it went powerband wise (now remembering how the cross-ram setups worked, the max wedges versus the standard cross rams). Definetly thinking of downsizing the carb to a 600 or 650 since I'm sticking with 302 for a while now.

[ronburgundy]

a phenolic spacer would likely make the warmup period a living hell on a carb. wouldn't it just ice up?

[Tomak]

Haven't looked at a Perfromer RPM in a while... is the divider in the center between the 2 sides cut down, or does it reach the top of the carb pad?

If it is all the way up, use the open spacer

[84stanggt-top]

a phenolic spacer would likely make the warmup period a living hell on a carb. wouldn't it just ice up?

Well, I'm summer only with this car, but that's a good point, since I'll have heat extraction already with the cowl hood, thanks.

is the divider in the center between the 2 sides cut down, or does it reach the top of the carb pad?

It reachs the carb (pro products crosswind)

Well, guess I'll save the $50 or so, since there will be no benefit.

Thanks for all the replies.

[Matthew]

I've seen those spacers work on a Dodge setup quite well actually. They essentially increase the plenum size, which is helpful.

Also, spacers on EFI manifolds lengthen the runners and move the power band DOWN the RPM range, not up.

-Matthew

[Tomak]

Originally Posted by 84stanggt-top

Well, I'm summer only with this car, but that's a good point, since I'll have heat extraction already with the cowl hood, thanks.



It reachs the carb (pro products crosswind)

Well, guess I'll save the $50 or so, since there will be no benefit.

Thanks for all the replies.

No, no.... it will help if the divider is all the way up. Spacers are funky though... they really help on some apps, sometimes the 4 hole is better, sometimes open... hell, I even saw a NVH super sucker that made a HUGE difference.... but only when it was upside down.

I have never seen one hurt though! And they are not $50. They are about $20 at PPC in the cheaper brands.