Low Compression
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Low Compression
I have a 74 360 that I have been told has 90lb in two cylinders. It runs perfectly, no smoke, little oil use, never gets hot and had plenty of power.
Could this be exhaust manifold, valve job time or need another compression check?
Any help would sure be great. I have forgotten much after high school autoshop.
Could this be exhaust manifold, valve job time or need another compression check?
Any help would sure be great. I have forgotten much after high school autoshop.
Post Fiend
Joined: Feb 2000
Posts: 5,130
Likes: 8
From: Brea CA
Low Compression
I would suggest another compression check. When you check it, make sure the engine is warmed up, remove all the spark plugs, disable the ignition, block the throttle wide open, screw in the gauge and crank the engine for 3 or 4 compression strokes. Write down the highest reading for each cylinder on a notepad with a sketch of the engine orientation and cylinder number. After performing this on all cylinders, check your readings for any low numbers. If there are any, squirt 1 to 2 teaspoons of motor oil into the suspect cylinder and repeat the compression check. Note down if it increased dramatically or not. If it did, you have ring problems, if not you have valve or head gasket problems. If you have 2 adjacent cylinders reading low, it’s probably a head gasket. When rings go, they usually all wear out at the same time and give consistent but low readings. I suspect you have valve or head gasket problems as these lean-burning retarded cam late model 360’s like to eat valves. Good luck and let us know what you find.
Barry
Barry
