A Few Small Problems

[Truzi]

I finally got exhaust, so took the car out for a little ride. It tends to hesitate when I hit the gas (the accelerator pump is new).
At one point, just giving it a little "extra" gas around a corner, it backfired through the carb and wouldn't restart.
The choke plate had lodged shut, I had to force it open.

How can this happen and how can I remedy it? Its a 600 cfm Holley and not a performance engine. Obviously I need to figure out how to stop the backfiring, though it has never jammed the choke before. I have noticed the choke moves freely except for that last 1/4 inch to closed.

Also, I can see air bubbling through the fuel line (clear filter before the carb). I have no obvious fuel leaks, and the pump is new. I will track it down, but in the meantime, is this cause for concern? The car is just basic transportation.

[GS69350]

Its a 600 cfm Holley and not a performance engine.



There's the problem. Get a Q-jet back on there.

Dan

[Dan Healey]

:Smarty

And make sure you get a q-jet from a 350, not a 455. They are a little different. I have an extra if you need one.
Dan

[GS69350]

Got a q-jet from a 69 430 on my car now (350) works great. had a 71 455 carb on it once too... good stuff. didn't like the 69 350 carb, it felt weak at the top end compared to the bigger ones.

Dan

[Mark Demko]

I agree, use nothing smaller than a 750 cfm. carb on a 350, whether its a Quadrajet or Holley. Mark:beer

[brblx]

stupid question - when people stick a more modern carb on a performance engine, why do they usually go for less cfm than with an old q-jet or such? (case in point with the holleys)

[Truzi]

Its interesting that the car pulled harder with the Q-jet when the secondaries did not work than it did when the Holley was new. The car is no speed demon, but pulled well with the Holley. Unfortunately it sat for a few years; now I'm trying to debug everything. I think most my problems lie in the carb.

My original Q-jet was shot, and I was told to go with a 600 cfm Holley (by a Chevy place, LOL). That was years ago when I knew absolutely nothing about carbs. Now that I know almost nothing, I want a Q-jet, but can't afford a carb.

I'll be scrounging junk yards, so any info on what carb to look for off what cars, numbers, etc., would be appreciated.

[CyberBuick]

I believe I have a '70 Q-jet around here somewhere that I didn't use. I would offer the base plate with it, but... one has screws stuck in it and the other isrusty.. lol When in the yards look for one that starts with 7040 (Rochester, Buick, 1970) The last number depends on the tranny you have.. Even for Auto, Odd for Manual.

If you want, I have two extra q-jets in peices if you want a go at it. I gave up and found me a clean one.. lol :grin:

Happy Hunting!

Scott