I have a 72 delta 88 with the 0riginal 455 and sometimes when i go to cut the car off, the engine makes a clunk noise and wont cut off. I can turn the key back to the on position and the car comes on like it wasnt off. does anybody know why and what i can do to fix the problem. 1 more thing... when i start my car warm or cold, grey smoke comes out the tail pipe for like 5 seconds. any suggestions...

 

It sounds like a timing problem . I'd get a timing light and check the ignition timing . and also if the engine is all original you could have a timing chain going bad .

 

The smoke on start up is from the valve stem seals being bad. They get hard a brittle and crack off. Due to old and high mileage.
The run on after the key is off, is from carbon build up, most likely from the stem seals being bad. When the car is hot, this is common, also alot of slow driving doesn't help.
Might want to run some carbon cleaner thru the tank.

Gene

 

Check the timing and run a higher octane fuel as well. The higher the octane, the less it will want to run on when you shut it off.

 

Yep, It sounds to me like It is diesiling.

 

He says it runs on when he shuts the key off. With the ignition off, there is no spark so timing is irrelevent. Running carbon cleaner is the first thing.

He also needs to check for high idle speed and also check everywhere for vacuum leaks. These three things are the biggest cause of "dieseling".

 

Isn't there a idle stop (dash pot???) that allows the throttle blade to close completely when you shut the car off. I have A.C. car and I had a non-functional gizmo of this sort ..?

 

It's unlikely but possible that late timing may help hide a pinging problem enough to fool a guy into thinking the cheap gas is working good enough. I've seen crazier things happen.

 

Yeah definately sounds like carbon build up, I would run sea foam through the motor to help clear the some of that carbon out.

 

anybody look at the orginal post date. It is 2 yrs old.

 

now that is funny.

 

 

All that technical advice wasted.

 

It will help the next person that problem happens to.That guys probably not even around anymore though.

 

EXACTLY

This is why some people on this site insist on ensuring information is correct and accurate, at the risk of appearing to be "snobby" or "know-it-all".

 

Watch the seafoam. I like it and use it on all my old cars when i first get them. I use the sea foam bofore i change the plugs. I have seen a few times the sea foam foul out the plugs. So sea foam fist, new plugs next. Then some burn outs! LOL