Just ran a compression check on my TPI 305 and wanted some input.
The engine is 2 years old. I assembled it myself. New block, aluminum cylinder heads, ect. Since I installed it, it has always had a slight part throttle miss and used coolant (a couple of ounces every few hundred miles or so). No exterior leaks or white smoke out the tailpipes. I rented a compression tester from AutoZone today hoping it would shed some light on things. The test was done with all 8 plugs removed and the throttle held wide open. Due to unfriendly header pipes, I only got 5 of the 8 cylinders tested, but I think the results on the 5 I did get speak for themselves.

# 1 - 99 PSI
#2 - 106 PSI
#3 - 101 PSI
#4 - 100 PSI
#5 - NA
#6 - NA
#7 - 98 PSI
#8 - NA

From other posts I hear cylinder pressure should be from a low of 135 PSI all the way to 180 PSI. These all seem WAY low to me. I am thinking I have used the wrong type of head gasket. Any input would be appreciated. Thanks!

 

Yes they are low. You might need to do a leak down test, far more useful. Did you use 350 heads on that 305? Maybe they have large chambers.

 

They are Trick Flow aluminum heads for the 305. They have 56cc chambers and give me a CR of about 9:1. I used head gaskets suggested by the Summit Racing tech line. Maybe they are the wrong ones. I'm just fishing for some input before I tear into this thing. Thanks for the reply!

 

The absolute pressure value is virtually meaningless. The relative values between cylinders are what's important.