The Stovebolt Site Forums The Shop Area Engine Shop 292 tune up help

Rebuilt the Roch B carb, put in all new ign parts, starts and runs good, dwell @ 32 deg, timing @ 4 BTDC and carb and all seems well. BUT, it hesitates when I step on the gas. Been doing that since I bought it and nothing has helped. Oh yeah I also put new exhaust manifold on so that gasket is new along with the entire exhaust. I am perplexed? Any ideas where to go next

Try setting the timing 2-4 degrees higher. Hook the vacuum advance to manifold vacuum if it isn't already. Make sure the accel pump puts out a good shot right off idle. If those don't work pull the top off the carb & make sure the float level is correct. You might set it 1/32 higher then specs. Look at the main jet & see what size it is. Sometimes these carbs are exchanged for remans & usually come off a 250. You might have to get a larger jet or drill it out.

Thanks, I did advance the timing a few deg and it is smoother and better response, I also reset the float level and made sure it was 1 9/32". Now it occasionally backfire through the carb. Still something amiss here. Maybe the jet is the problem like you said

I think the new gasket on the intake is leaking. Sprayed some PB blaster on the seam where it meets the head and the RPMs went up. Will that cause the backfires and hesitation? I hate changing that gasket again. Is there an easy way to do it? Do you tighten the 3 bolts that hold the intake and exhaust together last? There must be a trick to getting them on right and tight? Frustrated

Isn't PB blaster a little messy. I just use carb cleaner when checking for leaks. It evaporates very quickly. Yes, tighten the three bolts last. Are you using a one-piece gasket with the metal toward the manifold?
My B always worked well with ported vacuum.
My 292 is fairly cold blooded and when I had the Roch B on there it needed the choke at stops for several miles until it was warm enough. Winter was worse. The Carter AVS 4bbl on there now gives a bigger throttle pump squirt and I don't need the choke as much when cold.

Craig, the leak sure can cause the problems you are having. The engine is sucking air from the leak causing a lean condition. The best way to fix the leak is to have the intake and exhaust machined or ground. I bolted both manifolds together with a new gasket using the three bolts, then took it to the local shop and had them grind the flange side even. It was pretty cheap and didn't take but a few minutes. I can now remove and install with out leaks. The truck ran much better after the grinding.

You can try loosening all the bolts and adding some sealer around the intake ports, adding some lube to the nuts and spacers so they turn easyer also helps. Tighten the bolts on the head first, once they are tight, snug up the three going to the exhaust manifold. If you will notice, some of the bolts going in the head are higher then the others, try tightening them first so its not drooping down. Also hold it up so the bolts don't have to try and lift the whole assembly up flat to the head.

With a mismatched intake and exhaust manifold, you may have a hard time getting them to seal, I know I did. Joe