cylinder compression 90 chev 305
roonie
12-31-2004, 12:03 AM
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
01-19-2005, 02:36 PM
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
01-19-2005, 06:05 PM
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.
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