The Stovebolt Site Forums The Shop Area Engine Shop 348 not revving

Finally got the gas tank back in and fired my 59 2.5 ton up but it is not running right and in a way I havnt seen. I just rebuilt the carb, but for a while it would not idle without the choke pulled way out. I adjusted the point gap and it got better but not always fixed. The biggest confusion is that when i try to rev it, it sputters and sometimes dies but if i give it a half throttle for a second, it will stop firing, then rev up pretty high and stay there. Throttle isnt sticking open. Some of it seems like a vaccume leak but there are not many lines and when I actually disconnect one it runs worse. It also backfires out the carb and exhaust depending on choke/throttle. Not sure if any of it could be the governor? The only other vaccume option I can see is the brakes which also lost all their fluid with no visible leaks.

Thanks for the help

Sounds like you need to have this thread moved to the Engine Shop section...you'll get better help there with your carb and vacuum leak issues.

Was this a running/driving truck before you started having issues or are you bringing something back to life after a long nap?

Do you have a vacuum shift 2-speed rear and does it work?

Disconnect the big vacuum line off the back of the intake that goes to the firewall and plug it at the manifold (it serves the Hydrovac and rear 2-speed)..did that help any?

Others will chime in with more/better ideas to try...

Mike B

I think the fire department sold the truck around '99 and im not sure if it was ever on the road after that. The guy i bought it from said it ran about a year and a half ago but im not sure to what degree.

Its got the electric rear end so no vaccum there and I think the only thing left hooked to vacuum is brakes and pcv.

I plugged the line to the brakes and it may have helped a tiny bit with the stumble, but did not fix the rpm not coming down. I shined a flashlight down the carb while it was running (very fast "idle") and only saw gas coming from the rear annular boosters. The front did give a good shot when i gave it gas though. But not from the middle of the front boosters.
At a normal idle, it looked like it was running correctly off the idle circuit, no gas from above the butterflies.