1971 Chevy Truck Bogs and sputters when ACC. From idle

WRWILSON41

MEMBER
1971 CHEVROLET TRUCK
6 CYL
2WD
AUTOMATIC
199,000 MILES

I have a 250 with Rochester 1bbl Monojet carb recently rebuilt. The truck will crank up fine, idle fine (out of gear) and run at speed fine. The one thing it will not do fine is accelerate from idle well. Even sitting in Park, if I give it some gas it will bog down, sputter and try to cut off. When I try to put it in gear, just that load is enough to bog it down and cut off. I have checked/replaced all the vaccumm lines leading into the carb, set the timing (vaccumm loose) at 4 degrees BTDC and replaced points, plugs, plug wires, and ignition coil.

Any ideas where to go from here, stumped.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Hi there and thanks for the donation it helps runs the site

Make sure the point gap is properly set or check it with a dwell meter once this is done NOTE: Dwell angle will change the ignition timing-but ignition timing will not change the dwell-check the ignition timing plug the vacuum hose that goes to the vacuum advance and set the timing. If everything are okay-check if the accelerator pump is squirting fuel when you pull the throttle back if not there's a problem with the pump circuit. Also check fuel filter and fuel pump pressure

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires