wrxand280z Posted September 13, 2009 Share Posted September 13, 2009 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 Quote Link to comment Share on other sites More sharing options...
stravi757 Posted September 13, 2009 Share Posted September 13, 2009 You could try putting some oil in the cylinder and then do a comp test, if it goes up then you have a worn cylinder. But it could be a blown head gasket or maybe you need to adjust your valves... Quote Link to comment Share on other sites More sharing options...
hoov100 Posted September 13, 2009 Share Posted September 13, 2009 did you double check them to make sure it wasnt a false reading? Quote Link to comment Share on other sites More sharing options...
Challenger Posted September 13, 2009 Share Posted September 13, 2009 Whats the history of the motor? Was there a point that it felt a little less powerful/rough. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted September 13, 2009 Share Posted September 13, 2009 (edited) 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 September 13, 2009 by grumpyvette Quote Link to comment Share on other sites More sharing options...
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