roonie

what should the cylinder compression be on my 90 chev with a 305.I did a dry test and ended up with 75 lbs.at each hole.that seems a bit low to me.what would it have been from day one.runs nice but using some oil.have already done valve seals.no longer puffs apon starting.thanks

tirefryer93

You are right, 75 lbs is low. Stock should be anywhere from 130-150. My inclination is that your rings are worn, which is reasonable because of your loss of oil and low compression. Unless you want to give the engine a partial (or entire) rebuild, I suggest using some engine flush in your oil, drain it, then add a new change of Valvoline (best thing for chevys) and try a quart of additive such as Restore or similar. That should help seal the cylinder walls better and give you some better numbers on the compression gauge.

Fireplug

The main thing about a compression test is that they are all about the same reading. 75psi is low but if its running good and does not burn a lot of oil then run it.