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low cylinder pressure in sbc 350


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I have a stock 78 350 chevy with a 2 barrel carb and I checked the pressure in all of the cylinders today and the #1 cylinder was a 80 psi and the rest were at 120-150. I also have oil pressure just about always between 18-30 psi which is kinda low. My question is do I have a blown head gasket or a worn out cylinder. I'm hoping to just have a blown head gasket which would explain just one bad cylinder but I dont have much experiance with building engines to diagnose on my own. Any thoughts on how to better diagnose the problem.

 

Joe

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blown head gaskets frequently result in over heating or coolant in the oil or water vapor out the exhaust, since you didn,t mention those and only one cylinders involved its more likely a bad ring, damaged piston, worn cam lobe or burnt valve, Id sugest removing the spark plug and squirting some oil into the cylinder and re-testing, if it jumps up noticeably its likely a broken ring or damaged piston, if not try adjusting that cylinders valves, if still no change Id pull it and inspect it.

 

this is very useful

http://www.themotorbookstore.com/resmchstvi.html

Edited by grumpyvette
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