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vetteman 07-27-2008 05:46 AM

carb spacer plate
I have this plate, and was wondering if it would help atomize the fuel a little better at low to mid rpm's. I have a performer rpm, Holley 650HP, 1/2" open carb spacer. This motor was dyno tuned, but I never thought about trying this plate. This motor is in a 64 vette, 4-sp, 327-350. Any thoughts?

dawg 07-27-2008 07:31 AM

4 hole spacer plates help atomize the fuel/air in otherwise big manifolds.
helps get rid of the bog /hesitation off the line.
but judging from the pic that spacer is too thin.
at least 1" to notice a difference.

malc 07-27-2008 08:14 AM

It looks to be more of a gasket.
Stay with an open spacer, one inch better.
I went to a one inch open after a four hole and the difference was
noticeable immediately with the idle.
More torquey as both banks can call upon the whole carb.

Take a lookat this from CarJunkies may take awhile to load.

red65mustang 07-27-2008 09:08 AM

are you tuning for better at the strip or better on the street atomization???

here's a good spacers explaination article....

and there is another good article in the Knowledge Base link at the top of the page.....

yes, your present 1/2" open spacer may well be adding a few more WOT peak HP ponies...."but".... at street rpms it is making the RPM dual plane intake behave as a open plenum design because there is no divider wall at the carb bottem...

on a intake stroke the piston is trying to pull a vacuum to make a strong carb Hg (good velocity for excellent atomization) signal from all 8 of the intake runners cubic inches of area due to no divider instead of just 4 runners worth of area....
(and worse it's 1/2 the carb signal at the carb because it is pulling from both primaries)

if your looking for better street driving performance I'd remove the 1/2" open spacer and test drive it....the "high rise" RPM intake already has a plenty tall carb base to plenum bottem distance...

vetteman 07-27-2008 10:47 AM

Thanks for the feedback. Although the car does run well, I thought it could use a little tweaking off idle. Heat soak was the reason for the 1/2" spacer, and I did do some checking about adding another 1/2" to an already "high" intake, and came to a conclusion a 1/2" wouldn't really affect it that much. So I guess if i'm bored, i'll experiment with the four hole plate I have.

red65mustang 07-27-2008 11:14 AM

you can buy a oem approx 3/8" thick 4 hole insulating carb gasket at your local parts store for about $10?....

the Edelbrock 3/8" insulator 4 hole gasket is about $14?

vetteman 07-27-2008 11:57 AM


Originally Posted by red65mustang
you can buy a oem approx 3/8" thick 4 hole insulating carb gasket at your local parts store for about $10?....

the Edelbrock 3/8" insulator 4 hole gasket is about $14?

Maybe I overlooked those, but at the time I believe the thinnest,in phenolic I could find was 1/2". 4150 style. The purpose for the spacer was for heat soak, not tuning. But I believe,except for upper rpm's, the four hole insulator/spacer would be preferable for street. Although with a 4-sp, I can work with the rpm's to overcome the low rpm glitch.

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