Inliners International Forums General Discussion Engines Holley 390 4bbl

I have heard the Holley 390 cfm is hard to tune for use on a 261 engine.I know some of you run one,does it work for you? And what if any tuning did you have to do on the carb to get it to run smoothly without any flat spots or other problems?

Well, I ran one on a '68 292 for about 24 years -- if that's close enough. They can be tempermental and have an achilles heel in the power valve. You absolutely can't backfire or you kill the power valve. A 50cc accelerator pump kit blew out the bogging. I'm thinking about a 500 cfm Carter AFB [no power valves] for my next build-up: 292 @ .030-over. May have to settle for an Edelbrock, since Carter sold the farm.
Hope this helped.

Tony P,

Tuning the modular 4150/4160 holley carb is something of a lost art. The page included below is the best explination of a step-by-step method for carb tuning.
http://www.bob2000.com/carb.htm

FWIW, I used this with a 600cfm Holley on my 283. It's way too much carb for the engine, but with proper tuning, vacuum secondaries, and a 3.08 rear gear, I get 20mpg in my '56 hardtop. (at 65mph)

Gene