Hey guys. I just did a comp. test on my 8.8.1 81.5mm gsr. The motor has just been put back together and the comp. was 135 on all cylinders. Does it matter if the motor has not been turned back on since changing the headgasket? I think its a low after doing some reading. Any input appreciated.

 

Compression test should be done after engine is warmed up.

 

ok. Also should i keep the plugs in on the cylinders that im not working on. ( one cylinder at a time) or can all the plugs be out?

 

All plugs can be out. I take all of them out to ease the cranking process.

 

Warm the engine to operating temperature first before performing a compression test. Also make sure you crank each cylinder for the same amount of time, varying the time can change the results. You can leave the other plugs in there, or you can take them all out. If you test one with all the plugs in there, then test each cylinder that way. It's all about being consistent.

If you are still worried about the results, a cylinder leakage test will give you a more accurate answer of the engines "health".

 

Warm it up to be sure but 135 is low, even for 8.8.

 

With a cold engine and rings that haven't seated, seems like a fair number.

Also, make sure the throttle is open while testing.