ENGINE RUN ON

[ssl78]

I am working on a 20k mile L78 Camaro. The car always ran fine but the carb was leaking so the owner rebuilt the carb he also tuned it up points plugs cap wires. The smog was off the car so he also reinstalled that. He brought it over because it now runs on when it gets hot.
Heres what i did checked timing and set it at 4 relaced the carb with a known good one replaced heat riser because the old wasnt opening and disconnected hoses at the check valves and plug them The car still runs on any suggestions.

[BARRY]

HI I HAD THE SAME THING HAPPEN TO ME SUT THE CAR OFF IN GEAR

[nuch_ss396]

Is this an automatic or manual transmission L/78?

[VintageMusclecar]

What rpm is it idling at and what kind of fuel is he running in it?

Eric

[@wot]

you can try a colder plug, or one that does not a projected nose. More octane. If an auto, shut it off in drive, remember to place lever in park. Run on is essentially dieseling that is fired by a hot spotg in the combustion chamber. Some carbs have a solenoid to prevent this.

[ssl78]

Its a four speed car its idling around 850 rpm premium unlead with Hodell octain and lead additive. Remeber it didnt do this before he changed everything. Eric how long of a wait to have a carb rebuilt.

[TDW]

If nothing except the points and condensor were changed in the distributor, like the springs, wieghts, VA, then I would retime it. Disconnect the VA, set the total timing at 36-38, hook the VA back up and drive it. I think the 4 you have is too slow.

[396L35]

I'm with Tony on this "set the total timing at 36-38"... This should do the trick...

[L78steve]

When you reinstalled carb.and started for the first time did you have to increase idle speed screw?If so it may have been necessary,to cover up a vacuum leak.Check your work.The more the throttle plates are open the better chance for run-on.

[VintageMusclecar]

John;

A basic rebuild is only a 2 or 3 day turn-around normally, and restorations are running about 1 or 2 weeks right now.

I also agree on bumping the timing up a little to see what happens.

Are the plugs stock heat range?

Is there any spark rattle under normal driving conditions?

Eric

[wfomkivdrvr]

you may want to check idle vacuum for the power valve me be pulsing at idle causing your run-on rebuild kits usally come with a 6.5 valve which would require a 13 in. idle vacuum. hope this helps!

[L34Pace]

Did you compensate the timing for the smog pump? If its a functional unit you will need to retard the timing a few degrees. Try removing the belt from the smog and see if it makes a difference. A functional smog system can be a PITA when trying to get a HP engine timed correctly. The first thing that came off the car for a reason.

[ssl78]

I did disconnect the hoses at the check valves and duct tape them off that eliminated the air pump