compression test.....

first off...stock LS1...

what should the compression in PSI be on each cylinder?


second...

i have a misfire problem, think it's a bad lifter. it is intermitant...misses on cylinder 7 for a few seconds, then runs fine...then misses again...etc.

can i just pull the sparkplug, put the compression guage on it and run the engine to test compression? should i unplug that injector?

or should i just test it by turning it over with the starter?

i'm worried that if i just do the starter it could be reading the time when it seems to NOT miss...

if i run it i should be able to watch it fluctuate (assuming it IS a bad lifter) from proper compression to a period of bad compression.

any help would be greatly appreciated

can i just pull the sparkplug, put the compression guage on it and run the engine to test compression? should i unplug that injector?

I don't think you run the car to do a compression test. I believe you bump the motor over.

i have a misfire problem, think it's a bad lifter. it is intermitant...misses on cylinder 7 for a few seconds, then runs fine...then misses again...etc.

Can you pull the valve cover off and watch the pushrods move up and down? Making sure the lifters are moving correctly?

Can you pull the valve cover off and watch the pushrods move up and down? Making sure the lifters are moving correctly?
If a valve is bent though, you won't see it just by watching the valves and lifters moving. I don't think that tiny difference would be visible to the naked eye?:think:

thanks guys..

did the compression test...

180psi on 3
170ish on 5 (sometimes missed on this cylinder)
000psi on 7 (major misses on this one)

so i guess it answers my question...bad lifter