LigHtEmUp01

so i ran a compression test and the right side cylinders were around 130 and the left side the highest i had was 90 the rest were 80 and 85. what could this mean?

robmnrd

It could mean it's time for a rebuild with all the goodies.

BlackBird87

iTrader: (6)

explains why youre down on power, prob need to be torn down again

trilkb

iTrader: (4)

This is just a shot in the dark here....but i would say from the information givin it means that you are having some kind of a...ah whats the word? i guess you could call it a "compression loss"(??) due to the numbers being lower on the left side of the engine vs the right side of the engine.

I guess what im trying to say here is there is a difference in the numbers you have stated. this gives me the idea that its losing compression on the left side vs the right side.

Perhaps turn your headlights on and try again? if this doesnt work, get the codes cleared.

defaultexistence

iTrader: (11)

Boy you sure come across as an up and coming smart *** ******** with that ****

I'm sure since he can do a compression test ..he knows he has compression loss..
some explanations could be improperly set up valve lash ,cam timing ,worn /bent valves ,blown head gasket,cracked head,...
OP ,have you had motor apart recently or just finished build ??

Big Al

iTrader: (1)

Remove the valve cover and tap the top of the valves in the lowest cylinder lightly with a small hammer, then test it again. It it stays the same, put a few drops of oil in the spark plug hole and see if it goes up. From that you can determine what's going on.

I would first be sure you're getting a good seal to the compression gauge, and be sure the battery is not running down. Tie the throttle open part way. Disable the ignition. Most good testers screw into the plug hole. Don't discount the battery. If the RPM slows the numbers will go down. Crank through five compression strokes and stop. It's best to do the test with the engine at operating temperature. On my Z28 that would cause major burns, so it's not an option. Cold engines will read lower compression numbers than warm engines, high numbers are not important, even numbers are.

Al 95 Z28

96LT1355Z28

iTrader: (2)

^^ Good explination, also it helps to unplug your injectors so your not washing down the cylinder walls.

lttransam

iTrader: (12)

i had compression issues all last summer, pulled the motor and ended up being the heads.. i had 3 valve seats that cracked and wasn't sealing, i feel for ya man i HATE compression issues..

trilkb

iTrader: (4)

lol default, He knows compression is down, he knows the numbers, i honestly read it and didnt understand what else he needed to know lol.

LigHtEmUp01

obviously i know im low on compression the question here was what could cause one side to be so low? im leaning more toward valve issues. this motor has less than 800 miles on it

96capricemgr

iTrader: (1)

Obviously the difference is critical but have you ever used the gauge on another known good engine??

I have never seen a stock LT1 crank below 180psi or so and after an AutoRX treatment that engine at over 180k miles was back up over 195psi. All my modded stuff has been 225+psi.

Same gauge read 70-75psi on my 40yo 6hp boat motor which was right in spec so I have faith in my gauge, it doesn't just read high.

RedHotG8

iTrader: (1)

If you only have 800 miles on the motor, you should ask the engine builder why the compression readings vary so much, not us guys.

LigHtEmUp01

he said because the rings are not seated yet i used a different gauage and the lowest i got was 165 and highest 205

96capricemgr

iTrader: (1)

IMO is the rings aren't seated yet, they wont. Was the tune really really bad at first or anything?

RedHotG8

iTrader: (1)

When the rings get seated do another compression test. If the readings still vary your engine builder better have a better answer for you.