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383 compression test.

SandDiesel

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Just acquired a 65 Belvedere with a 67 383 and 516 heads. Assuming it's stock what's an acceptable psi range and what should a fresh stock rebuild reach for psi? The seller inherited the car and believes the motor is modified but just looking for a baseline I guess.
 
I'm thinking 150 PSI is about right.
 
I don't know the details on my 383 with 516 heads (other than ~25,000 on rebuild), but it was ~135 psi dry and ~150 psi wet.
 
I don't know the details on my 383 with 516 heads (other than ~25,000 on rebuild), but it was ~135 psi dry and ~150 psi wet.
Was the engine warmed up and had the throttle wide open when you tested it?
 
Was the engine warmed up and had the throttle wide open when you tested it?

Engine cold and no carb installed. Is there a general/ballpark number of increase in the readings one can expect between cold and warmed up?
 
Tested one once like that...cold then hot but it was in such bad shape, it really didn't help much until I threw in some oil in the plug holes.That told me the rings were shot....
 
Crankys right about doing a hot test...Cold is a different story as far as true compression..
Petty Blue 67 GTX
 
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