[trv24217]

Hello, I just purchased a 67 GTO , The previous owner replaced the points with a petronics system. The car has never to our knowing had a new timing chain so who knows what condition it is in. The problem is the car contunues to run on or diesel when you turn the key off. He admits to trying to adjust the distributor and idle speed and even the fuel air mixture a little. What sequence of steps do I need to get the car to shut off. I do have a timing light. It did work before he tried to fix it. You know that story.
Thanks
Tom

[68lemans462]

Here is some info on "dieseling"

http://en.wikipedia.org/wiki/Dieseling

[limejudge69]

In most cases, a high idle speed is the cause.

[scott cedergren]

check for vacume leaks, i use carb cleaner around the carb and intake.

[salem1912]

Try idling down the engine, unplug your vac. advance-- set your base timing then adjust your idle. If your idling hi your mechanical advance maybe "engaged". Base/mechanical/vacumn timing. Also your secondary thottle blades maybe sticking causing hi idle. Good Luck

[lust4speed]

First, drain the gas and save it for your lawn mower -- replace with premium fuel.

After that, it's just a matter of elimination. Most of the time the problem is aggravated by retarded timing which builds much more heat in the cylinders. This retarded timing also requires a bigger throttle opening, and as mentioned above, greatly contributes to run on.

Since you say the engine ran ok before adding the Pertronix, I would rule out the vacuum leak for now. I'd even make sure that the previous owner didn't swap a plug wire or two when he put things back together.

And last, you might have to check the quality of his installation of the Pertronix. While the unit is fairly foolproof, there are a few clearances that have to be checked. For that matter, borrow a known good Pontiac distributor off someone and give that a try if the easy fixes don't work.

[trv24217]

Thanks everyone....