Do you need to have an Edelbrock part # 2732 "Square-bore to Spread-bore Adaptor Plate" (or its equivalent) if you are using a Holley 4150 Square-bore type carb on this intake?

I bought a dual plane Performer used off ebay to replace a single plane intake I had on my 455. The single plane was rated for 3000-6500 rpm and my engine wasn't built for that (it looked cool though...). It didn't idle very well and performance was lacking down low. The Performer didn't come with instuctions, but, its only an intake. I bolted it on, put on a new square-bore carb gasket and dropped my carb in place. The car is idling rough and the vacuum readings are eratic.

I just read the instructions for this intake online and they say to use the part # 2732 Square-bore to Spread-bore Adaptor Plate when not using a spread-bore OEM type carb. I take it they must mean it, and I probably have a vacuum leak that could be causing these symptoms.

Are the rest of you that use this intake and a square-bore carb using one of these adapter plates? Have you ever not had one on there and had this problem?

 

The EGR SBO Performer has a thinner flange, needs the adapter. I thought the wider pad on the other manifold's was to use multiple carburetor's without the adapter. Spray carb cleaner on the carb flange with the engine running.

 

Why not run a quadrajet that the intake was designed for???

If you want low speed response a quadrajet will do that with their small primaries which speeds up the intake velocity

 

I actually ordered a 800 cfm Stage (2) Quadrajet set up for my 455 from SMI Carburetors to replace the QFT 780 vac sec square-bore carb I was using because I couldn't get the carb to behave! Now I am wondering if the reason the QFT carb wouldn't shape up was because I didn't have this "plate".

This intake has both square-bore and spread-bore mounting holes, so I'm not talking about one of those aluminum spacers with the studs to change the bolt pattern. The 2732 is just a 1/16" plate that "seals" the carb pad for a square-bore carb.

I talked with an Edelbrock tech today and he said I need the plate, the Summit Tech line is telling me the same thing. They only cost $5.95. Edelbrock guy said if I had bought the intake new, one of them would of been included. I've got one coming so I can see if it helps.

The QFT carb actually idled better on the Mondello single-plane intake I took off, and it was a square-bore carb only carb pad. I guess I was just wondering if any other Olds big block fans had any problems without this plate? Did one of these come in the box when you bought your Performer 2151?

I still want to try the Quadarjet, and it won't be ready for three weeks. But if this QFT carb shapes up with this simple addition, I;m going to be bummed that I spent money an another carb!

 

Did it shape up with the plate?

 

This thread is 2 years old
joepenoso

 

Yes I know that...thanks.
I was hoping that he would still respond (CO emailing him someone posted to his thread) as Im setting up similar set up, and curious how it worked out for him.

It's also good info for the site to follow up so others with similar issue will have conclusion.

If he doesnt respond, I might recreate scenario as I ordered the 2372 plate already. The 2151 Edel install notes reccommend plate as well as the Edel carb install notes.

 

I run a performer, Never ran a spread bore on it, just square bore carbs. I've tried it with and without the adapter plate. I don't run it with any more and use a 4 hole gasket. That seems the best overall combo, no vacuum leaks.

 

Good info, thx. Was there any specific reason you didnt like the 2372 plate? I got a good square bore gasket, but I also got the plate on order.
$9 bucks, good to have just in case.
Thx for posting your info.

 

With the plate it does not isolate the 2 planes, mine runs better without it and the carb bolted down directly to the manifold. I run a good quality 4 hole gasket.