Compression Tests 29ccpu

Gary WA

Gary WA

Well-known member
What are your thoughts on test? No. 1 low? For a model A Friend.
 
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Does not appear to be oiling the spark plugs. No change with oil points to valves not sealing. I guess it could be the head gasket is leaking on cylinder #1 and #4 is dropping off. I will stick with valves. A leak down test would verify which way to go.
 
GeneBob is on the right track. Give each cylinder a shot or tow of oil and repeat the test. If the readings come up, it's the rings, if they don't, it's the valves so long as the head gasket is sound. A leak down test will tell all.
 
If you pressurize the cylinders, you can use your ears to tell what is leaking. An exhaust valve will hiss out the tail pipe, an intake valve out the intake manifold, and rings at the oil fill tube. I think it is called a leak down test. If the radiator is bubbling the head gasket is leaking.
 
If you enlarge the op’s photos you’ll see that they had no change with oil. Adding oil in a cylinder question, do you just pour some oil into the plug hole or do you use a squeeze bottle and squirt the oil onto the pistons ?
 
Synchro 909, as Big hammer said, if you blow the picture up you can barely read the "with oil" line. I could barely make it out but that is why I skipped the compression test step you correctly suggested.
Actually, when I got my Model A, I kept trying to get more performance and nothing was making an improvement. I did a compression test, then a leak down test and found NONE of the valves were sealing. I took off the head and took out the valves and it looked like someone had used rocks and a hammer to make the valve seats in the block.
I pulled the engine for a completer rebuild.
 
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