Plastic phenolic spacer

[vitamin_c95]

So yes, I added one after researching on here about vapor lock. I added a one inch edelbrock brand. Sure, my vapor lock is gone, but I sure as heck cant get the truck to idle smooth. I'm suspecting vacuum leak from gasket or spacer. Anyone have problems getting the plastic spacers to seal? It has two edelbrock gaskets. I've tightened down the carb bolts a couple times thinking they were tight, but don't want to strip the bolt holes or crack the spacer but i sure as heck cant stop this rough idle. Cruises fine.

71 c20 longhorn, 350, edelbrock 1406, aluminum edelbrock intake (both were already installed when I bought this truck a year ago).

[geezer#99]

We assume you have a gasket then the spacer and then another gasket then the carb.

[HO455]

It's not uncommon for those spacers to be warped or the top and bottom sometimes are not true to each other. Wet sand the top and bottom with the sand paper on a piece of glass to remove the warpage. That will also help if the surfaces are not true to each other.
A couple of metal rulers can be used to find differences in the surfaces by placing the spacer on a true surface and hold a ruler on the top with half the ruler off of the spacer and measure the distance between the true surface and the bottom of the ruller and record the number then repeat on all four sides. By having the ruler stick past the end of the spacer 6 inches or so will make any problem with the surfaces being out of place more apparent
.

[vitamin_c95]

Originally Posted by geezer#99

We assume you have a gasket then the spacer and then another gasket then the carb.

Correct. 2 edelbrock gaskets

[vitamin_c95]

Originally Posted by HO455

It's not uncommon for those spacers to be warped or the top and bottom sometimes are not true to each other. Wet sand the top and bottom with the sand paper on a piece of glass to remove the warpage. That will also help if the surfaces are not true to each other.
A couple of metal rulers can be used to find differences in the surfaces by placing the spacer on a true surface and hold a ruler on the top with half the ruler off of the spacer and measure the distance between the true surface and the bottom of the ruller and record the number then repeat on all four sides. By having the ruler stick past the end of the spacer 6 inches or so will make any problem with the surfaces being out of place more apparent
.

I know what I'm doing tomorrow! Appreciate the idea

[HO455]

Originally Posted by vitamin_c95

I know what I'm doing tomorrow! Appreciate the idea

You're welcome and good luck,

[special-K]

I've never stacked the spacers. No gasket required between? Would that not help with the minor irregularities?

[vitamin_c95]

Manifold>gasket>spacer>gasket >carb

Just a single one inch spacer

[Corts60]

Spray carb cleaner around the base with engine running, if RPM's change you'll find your leak.

[KevinK7]

Originally Posted by Corts60

Spray carb cleaner around the base with engine running, if RPM's change you'll find your leak.

Just what I was thinking. Had something similar and this located the issue.

[special-K]

Originally Posted by vitamin_c95

Manifold>gasket>spacer>gasket >carb

Just a single one inch spacer

Got it! Just reread it and see you said 2 gaskets not spacers. Cancel my remark. Carry on

[burnin oil]

I have had a couple spacers where hollow underneath that caused issues. One let there be a leak between it and the manifold. Had another where when stacked had a slight gap due to milling differences. Be careful clamping the gaskets as they will leak if the carb base is being warped by bolt torque. I really like the thicker factory quadrajet gasket for stopping leaks. With some digging at jegs or summit you can find them for square bore carbs. As a last ditch effort a little silicone sealer between the intake and spacer should work also. Just don't go thick.