Are there any drawbacks running a square bore carb on a spread bore intake?

Im running a holley 750vs #3310 on this intake. I have the egr and choke provisions blocked off and using a square bore carb gasket.

 

It usually is no problem. On some spreadbore intakes you can get a vacuum leak at the base since the intake carb opening gets larger at the rear. On my Edelbrock Performer RPM Q-Jet manifold with a 3310 on top, I run a metal plate Edelbrock sells in between the carb and manifold to be safe. If you have enough room a small spacer would work too. But for that Weiand intake, I don't know if you would have any problems though.

HTH

 

I do have the room for a thick gasket, but not a spacer. Maybe a 1/4 inch gasket. Just wanted to see if anyone was having any trouble with this combo.

 

What Bunker said. You need that metal plate with (thin) gaskets on either side of it so you don't have any vacuum leaks.

People run Holley (squarebore) carbs on top of bellybutton-common Edlbrock Performer intakes (spreadbore) all the time and it work just fine. It'll work fine on your intake, too.

Thin spreadbore gasket on bottom + plate + thin squarebore gasket on top is still a pretty compact package- maybe 3/16" thick for the whole shootin' match.

 

Could a small vaccum leak be causing a strange miss that I cant find? Make the carb act up also.

Does this gaskets and plate come all together, or do I just buy one of each?

I do have one of the wire wove carb gaskets and just a paper gasket between the carb and intake. I might have to see what the local speed shop has in stock.

 

Without the "plate" there will be gaps where there is nothing to compress ("sandwich") the gasket and prevent a vacuum leak (especially around the secondary side of the carb just in front of the hold-down bolts). The plate is, in my opinion, mandatory.

If you've got vacuum leaks due to not using this plate it won't run right- especially at idle and light throttle. Once you get up around WOT it will usually run pretty good.

I don't recall if the plate comes with the gaskets or not- I don't think it does. But you already have a squarebore gasket under the carb, I assume, so all you need to get is an open-hole spreadbore gasket and you'll be good to go.

 

Thanks for the advice. I found the part I need from jegs. Summit also offers one. For like $7.00 it is definatly worth it to get rid of the headache its causing.

Thanks guys, I didnt know that it was required. I did question if it would seal when I bought the intake. It was like new and it was almost $200 new and I got it for $75.

 

Just went by my local speed shop. They had just what I needed!
I even picked up and extra gasket. Always nice to have one laying around.