Hey all, '48 chevy coupe w/305/350. Runs erratically... When outside temp is hot it runs beautiful and strong, when cool starts to high idle & rough when in gear. I was thinking vacc leak? It seems to run differently on it's own whim.... Stumped & frustrated. What are your thoughts? Posted using the Full Custom H.A.M.B. App!
If it started right after the carb swap, then its the carb. My sons was doing that..... Could even be a stuck advance plate/broken spring in distributor
I think you recently DOWNGRADED from Q-jet to edelbrock... Sounds like the problem is in the choke portion...good luck.
I recently had some carb woes with an edelbrock. Aside from tuning, I would bet money they there's some sediment and other crap in the carb. Yes, even a new carb.
Actuall, I must retract my post after re reading the OP. not sure if sediment would cause this problem.
I bet the problem is in the design difference. The intake is for the quadrajet, right? with those huge holes in the secondaries. The edelbrock will bolt up but you can have a vacuum leak at the rear because it is squarebore. Unless you bought a q-jet replacement type edelbrock, then they are the same as quadrajet. Edelbrock sells a flat plate that seals that area off or you can add a spacer to seal it off.
It is an edelbrock intake mated to the carb, Correct gasket. The trans crossmember was just replaced and trans tail us approx 2" higher now. Carb was installed " out of box" and ran great before tranny lifted. It then ran good at idle but, when put into gear it bogged badly. Pulled plugs and replaced with fresh, ran great again.... Now, starts to a very high idle.... It's crazy?!? Posted using the Full Custom H.A.M.B. App!
Hi Dave, It's attached. Would a leak in that line be a cause? Posted using the Full Custom H.A.M.B. App!
Put an angle gauge/inclinometer on the intake manifold carb mounting surface and get back to us with a reading. When the engine installed angle was changed, the carb float level was changed also. jack vines
A weak ignition will also act this way.... If you lifted the engine, and perhaps a wire got pinched? WHo knows.... Put the old carb back on and see if it acts the same....
A square bore Edelbrock on an Edelbrock intake for a spread bore (Quadrajet) carb can still have a vacuum leak on the secondary throttle bore. You have to use a metal plate sandwiched between 2 gaskets or an adaptor.
Brokenspoke, What are you driving? Is it a '48? I can't see the pic well.... Posted using the Full Custom H.A.M.B. App!
This is the manifold I'm using with the edelbrock carb. Looks like a match.... Car started & ran great today... No vacc leaks found yet. Checked around the carb, manifold to heads, lines. Posted using the Full Custom H.A.M.B. App!
Usually you have a whisle sound with a vac leak....I just found one on my car after a carb rebuild....I used the only carb gasket that came with the rebuild kit....found the leak by spraying brake cleaner around the base of the carb as that was where the sound was coming from....yep...it was the new gasket....wrong one for my car....last Hygrade made by standard for me. Forgot to say, the engine speeded up when I sprayed on the leaking area.
The Jalopy Journal
