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OlDatZMan

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No answer yet to my question so I'll rephrase: Shouldn't I be able to clearly sense compression on each cylinder when turning over the crank on this Z24 using a 1/2 ratchet even if the ratchet action isn't very fast? I know I certainly can feel compression when hand cranking my 51 Farmall Super A and it's only a 113CID 4 cylinder with 6:1 compression. I'll try just turning the crank pulley by hand which will make it easier to feel resistance. Just answered my own question: I can't turn the engine over by hand gripping the crank pulley. So I guess it does have compression and it's time to assemble a few more things to do a starter spin. Also knit together the exhaust system back together.

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On the up swing you would unless....

 

The cam is out of time with the crank... if all cylinders are zero

One or more valves are bent and can't close

Valve seat fell out and valve can't close

Hole in piston

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Not much of an update. A week ago I bolted on and torqued the supposedly fresh head with 4 new intake valves and 4 old lapped exh valves using yet another new head gasket, and the EZ LOK repaired rocker bolt hole. After getting the cam timing wrong and making a couple other mistakes I was too embarrassed to publicly admit at the time, I corrected the cam timing to the point of being able to do a compression check. Compression on the formerly good cylinders was unchanged. Compression on the formerly low #2 cylinder was low and unchanged, an unwelcomed surprise that whacked my confidence. That suggested bad #2 rings.

 

 

After a few days of mental recovery I rigged my compression tester to be able to inject air into #2, but not cobbled together as a full blown leakdown tester to check % leakage. I'm looking for location of the leak route, not the fact there is one. I fastened/ taped thin plastic wrap about 0.0005 thick over the crankcase vent, over the carb, and over the #2 exhaust port to try to show any flow out of 2 through valves or crankcase. Rotated crank so both #2 valves are closed. When injecting air with enough flow to hear flow, but not enough to force pistons to turn the crank, I can hear air flow in excess of what I would hope for a tight cylinder, but there’s no sign of flow out anywhere. Movement of plastic film may not be sensitive enough to be visible with low flow, and the carb cover admittedly cover has more leaks to reduce outflow if the intake valve is leaking. Can’t find my stethoscope (though I did find my missing Metro head I’d been looking for for two weeks), but I could not use the steth to move around to listen for air exit routes while I'm controlling airflow in at the same time. Will search more for the stethoscope but must wait til I get help to listen at probable leak locations, and then at improbable ones.

 

Edit/add: Found stethoscope, rigged to a listening tube, air flow quickly located coming from cam chain hole. (Valve cover is off.) Yeah I should have thought about other possible crankcase venting exits other than CC ports, ie breather....the vertical cam chain cavity is a big one though nt a port. Bad #2 rings.

Edited by OlDatZMan

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