2G how much will bigger cams affect a compression test?

[1996dsm]

I recently did a compression test on my car cause i had oil come out the dipstick. My results were very low 123-106-115-115.
The car runs great but these numbers now have me worried, i plan to purchase a leakdown tester to evaluate this further.

Until then do these #'s look as bad as i think for having bc 280's?

 

[henrysan]

My stock rebuild has about 5k miles on it. 7.8:1 compression 6 bolt. I never did a compression test till after my GSC S2 cams where installed. I was shocked at only 112 psi across the board, but the car runs great and burns no oil so I dont worry about it.

 

[1996dsm]

My car doesn't burn oil and pulls smooth. I was wondering if it was normal for readings that low, cause Id rather fix it while there would be less damage if it gave out during a pull not near home.

 

[JacksonAuto]

Stock shortblock? We usually see around 150-170 on a 9:1 engine with something like 272's. Stock shortblock would be lower. There are a lot of other variables but that should get you close. Regardless, 120's seems very bad and the difference beteween #1 and #2 is concerning.

I'd also look at your battery and starter to be sure it's fully charged. A low battery or weak starter motor will turn the engine over slower resulting in low compression test results.

 

[BogusSVO]

^^^^^ What Jackson said then add to it, more over lap, if the timing belt is off a tad will bleed your cylinder pressure down also.

 

[1996dsm]

Yes, stock short block.