I checked out a 65 coupe today and have a question. When I start the car the engine sounds very "violent" and loud. I originally thought the starter was just violently engaging with the flywheel. When the car starts it runs real smooth with no noises. But then when I turn the car off it like starts to get violent and like bang around for a second or two then stops. Its hard to explain but does anyone know what Im talking about or what it could be?

 

no one knows?

 

The run on after turning it off sounds like dieseling. It can be caused by a number of things but a properly tuned engine should not do that. The noise on start up could be the starter but it is hard to say without hearing it.

 

I always thought that was because idle was too high it would do that.

 

Not really, there has to be something in the cylinder that is igniting the fuel. Since when you shut off the ignition there is no more spark, something in there is causing the engine to keep running.

 

too high an engine idle, excessive carbon buildup in cylinders, wrong grade of gas, and/or an overheating engine can cause dieseling. on some cars people will turn the car off while in gear and let the clutch out with one foot on the brake to fully stop the engine.

 

The dieseling could be caused by the grade of gasoline. My '66 always does it if you try to run regular gas in it but with premium it never does.
Wp

 

thanks for the comments. dieseling sounds like that could be right. it definitely continues to run a little after its turned off. theonly weird thing was that it seemed to a little more loud and violent. I cant recall the exact sound but what is the worst thing it could be? Also the guy told me it has very old gas in and he just put a brand new holley 650 on it that isnt 100% tuned yet.

 

It is probably not turned at all. Bad gas sounds like an excuse but it could be true. That wouldn't help any. I would be curious to know everything that he has done to the engine. Is there a cam in it, what type of ignition does it have, that sort of thing. The worst thing is to buy a used car with a rebuilt engine and you don't know who built it or what is in it. Not saying the one you are looking at is rebuilt but if the engine goes right after you buy it could be devistating. Dieseling is not good for and engine and should be corrected asap if you buy.

 

When I bought my 65 the gas in it was very stale. Ran like crap. I ran it down to empty and filled it with premium (no ethanol) and it very quickly improved.