why does my car diesel when i turn it off

All that new this year is i ported my heads and gasket matched the heads to the intake. the timeing the same 32 total and the carbs the same 850 QF. it only did it like 3 time. not every time. any ideas thanks Josh

 

Idle is too high or idle stop solenoid is sticking.

 

Idle at 800

 

If it won't survive a lower idle speed, other issues come to mind such as piston and combustion chamber deposits, bad fuel or insufficient octane.

Devon

 

Cheap gas.

 

Thats fine but when you turn the key off does the idle solenoid retract and the idle go below 800 ? If it doesnt The engine will diesel. The idle screw on the carb should be well below 800.

 

I'm guessing the car doesn't have an idle solenoid.

Is the 800 RPM in gear or out?

 

Maybe he could tell us if it has a solenoid or not. In the meantime shut the engine off while its in drive.Added load will shut it down .

 

its a quick fuel 850 carb so there no solenoid. and its a 4 speed. im going to start by cleaning the carb. shoud i jet it up with the heads being ported? i really dont whant to run race gas. i drive it to much to spend $10 a gl.

 

What is the initial timing/timing at idle? What RPM is the 32 total at??

 

Switch fuel brands 1`st before chasing down a bunch of sh!t. Just because you have always used a certain fuel in the past, with no problems, doesn`t mean they haven`t changed their formulation. Hell, you might have just gotten a late tank of their "winter" blend and now it`s too volatile in the warmer weather. You could go back and get a "summer blend" now and the problem could dissappear without turning wrenches.

 

i did just fill it up. so maybe its bad gas.