Compression spec?

[DanielB]

anybody know the actual lbs of compression a stock 383 is supposed to have? i know the compression ratio is 10:1.

 

[moparchris]

Well it depends how stock it is. For a 10:1 383 I have seen compression in the 165 pound range. The important part of a compression test is that all the cylinders are within 10% of each other.

 

[DanielB]

the crank is stock running .030 over flat top pistons, so it should be very close if not the same as stock. I'm hearing a tick noise and smelling exhaust fumes thought it was a exhaust leak but after 2 gasket changes its still doing it and its definitely coming from the somewhere around the left head of the engine. My dad said its made the noise since he can remember and we've rebuilt it which makes me think maybe its got something to do with the heads (gasket maybe) dunno :huh: gonna start with a compression test and work my way up.

 

[BBillyC]

Hmmmmmmm.......leaking valve guides????

 

[DanielB]

man theres no telling but i'm definitely going to start a thorough investigation :brickwall:

 

[Big John]

Sounds like an exhaust leak where the manifolds bolt to the heads. They are made to bolt together without gaskets, but everything needs to be flat and smooth.

I have always bolted them up (no gaskets) and tightened several times after running, both when its cold and when its hot.

 

[DanielB]

its somewhere between a tick and a tap and it sounds like its coming from somewhere on the drivers side of the motor. I have 95-100 pounds of compression in #7 and 125 or so in all other cylinders. I really cant see where its coming from or know exactly what it is. Ive taken the valve cover off and still cant really see anything. Im thinking im just going to bring it to someone whos going to hear it and be like o ya its this and that because they do it everyday and save me the headache. so ya

 

[moparchris]

its somewhere between a tick and a tap and it sounds like its coming from somewhere on the drivers side of the motor. I have 95-100 pounds of compression in #7 and 125 or so in all other cylinders. I really cant see where its coming from or know exactly what it is. Ive taken the valve cover off and still cant really see anything. Im thinking im just going to bring it to someone whos going to hear it and be like o ya its this and that because they do it everyday and save me the headache. so ya

Do yourself a favor and go get a 3 foot length of vacuum tubing and hold one end loosely to your ear and fish around with the other end. I use this old time trick and it works everytime.

 

[John69RR]

Harbor Freight sells a Mechanics Stethoscope that works well also.
http://www.harborfreight.com/mechanics- ... 41966.html