do i need a carb adapter?

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garyl24

Apprentice
Jan 15, 2009
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southern illinois
my project has been on hold due to a lack in funds. now i am about to get started on it again and had a question. i have an 86 cutlass with a sbc. the intake is a edelbrock performer rpm. u ust got ahold of a qjet carb from another sbc. my question is do i need an adapter or can i just bolt the carb to the intake? reason i ask is because the intake has a square pattern and the q jet is a 4 barrell. thanks
 
Yes, I believe the Performer RPM has a square flange compared to the standard Performer which has a spread bore design.
You will need an adapter for square flange to spread bore.

http://www.summitracing.com/parts/EDL-2693/
 
Be aware that these adapters are a flow disruption that will pretty much negate any advantage from the intake swap. If you are just doing this as a temporary cost saving measure, I understand, but don't be surprised if performance is lacking.
 
It also comes in spread bore. just look at the shape of the opening on the top. If it's square, you'll need the adapter. If the back is bigger than the front, it should bolt on.
 
Scrap the Rochester Quadrajunk and get a holley 🙂
 
Quadrajet>Edelbrocl>Holley
 
I've seen the Edelbrock adapter mentioned in a previous post, and it's a decent piece. Some of the others on the market look horrible for flowing air smoothly. The increased plenum volume may require a little more jet. Be advised that a adapter/spacer will move the carb up higher. Hope you're OK as far as hood clearance. IMO a Q-jet is still the best choice for a street driver.

Bill
 
For the street Q-Jet and Carter AFB. For the strip a Holley. Holley's are too sensitive unless you have a DYNO. Then you can set up the fuel curves etc.
 
"Scrap the Rochester Quadrajunk and get a holley ' :roll:
 
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