My friend has a 302 in a 1970 f-100. Although it isnt a maverick I wanted someones expert opinion here. Today I set his idle (it was way off) so it is about 700-800 (according to my dwell tach) in gear and set his timing to 6 degrees before top dead center and the truck sounds great but it still wants to diesel just a tiny bit when you turn it off. Any ideas on how to make it stop?
Dieseling is related to throttle postion (open too far) Bump his timing back to 10-14 degrees BTDC, 6 Degrees is retarded--------litterally. Then reset the idle to 600 in gear.
So your saying the timing needs to be set farther and adjust the idle down some more. I didnt know where it was supposed to be. That was guess.
As long as the throttle is open too far the engine will "run on" after it is shut off. The curb idle solenoid was added to most cars with auto transmissions in order to let them idle at 600 - 700 in drive with the lean carbs and still shut off with the key. If it has a curb idle solenoid on it then set the idle in neutral at 550 - 600 and use the solenoid to set the speed in gear. That way when the key is shut off the solenoid will drop out and the throttle will return to the idle stop seting which allows the engine to stop.
yo, if it runs good an you just want to stop the diesel-ing, turn it off in gear. i had a similar prob in my suburban, the 454 would pop an spit, it even back fire hella loud if you let it keep going, so i turned it off in gear, it never did it agn. its a fix, it dont solve the problem but it fixes it.
6*BTDC was the factory timing setting, but it's not where the motor's like it set. It'll pick up a few ponies set at 10-14* , the idle speed will pick up too, showing you it's happier with the advance.
I would also check the condition of the balancer,I manage a Dyno shop and we have alot of vehicles with high mileage come in and the outer portion of the harmonic balancer has spun and the timing you are seeing with the timing light is way off. Good luck
