How to tell if I have good compression?

JustJeff · 05-31-2009, 03:44 AM

I'm looking into renting a digital compression tester. I was recently using a piston compression tester and found that my rear rotor had nice even compression all around so it was easy to read the analog gauge bouncing. The front one was a different story. I have uneven bounces and each compression pulse comes too quickly for me to tell the exact numbers.

Rear is about 110-110-110
Front is about 80-50-80

I'm told that a bad apex seal usually shows two low readings and one higher. Or that a bad side seal can cause one low reading.

I won't get enough use out of buying a digital compression tester or rotary compression tester, but I'm looking into renting a digital tester.

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05-31-2009, 03:44 AM	#1
JustJeff RCC Contributor Join Date: Mar 2008 Posts: 505 Rep Power: 18	I'm looking into renting a digital compression tester. I was recently using a piston compression tester and found that my rear rotor had nice even compression all around so it was easy to read the analog gauge bouncing. The front one was a different story. I have uneven bounces and each compression pulse comes too quickly for me to tell the exact numbers. Rear is about 110-110-110 Front is about 80-50-80 I'm told that a bad apex seal usually shows two low readings and one higher. Or that a bad side seal can cause one low reading. I won't get enough use out of buying a digital compression tester or rotary compression tester, but I'm looking into renting a digital tester.