just had a compression check done on my 239 ci flathead v8..............

........7 of the cylinders were in the 75 to 85 range, while the remaining cylinder tested less than 50................??

......secondly, the mechanic left all the plugs in while removing only the plug of the cylinder being tested......could this have affected results ?


thanks

 

I would rerun the test with all the plugs removed, also supposed to have the throttle wide open while cranking as well.

 

...............if all plugs removed....engine obviously will not be starting..............so what difference does it make having the throttle wide open on an old engine like this ?

..........thanks

 

all plugs out is for maximum cranking speed

throttle open is for max air into the engine

Nothing to do with not starting. Ignition should be disabled during the test, remove the coil wire.

 

the light just went on in the closet !!!.............thank you.............

I admittedly know little, but am eager to learn............really one the primary reasons I bought an old "simple" truck..............

......what a great resource this forum has turned out to be !

thanks again................I am sure I will be posting more questions..............

 

Good questions usually result in correct answers.

 

I had the same results with all the plugs removed. I pulled the heads and the two low cylinders had small pieces missing where the piston meets the cyl. wall. You could see the top ring. It looked like someone stuck a screw driver and pried in that area. rebuilder said he has seen that before. I sent it out to have it rebuilt. New style valve seats, adjustable valves, re-bore to 0.40 all new bearings etc. I had the water pumps rebuilt and gave to rebuilder to install. Total price about $2300.