Compression specs

[perk]

I'm wondering about compression. At a prepurchase inspection done a few months ago, mine measured 1-165, 2-155, 3-160, 4-155, 5-160, 6-165. If I remember correctly, factory specs are 170. I'm not sure how to interpret these? How do these numbers compare to yours?

Dealer service rep. told me that there is a variance of +/- 5-10 coming out of the factory and with my baseline being 160 I was within an acceptable range. He also said that the main concern is the difference from greatest to least, and it's when the difference is in the 20-25 range that there is a problem.

To help increase the compression, he suggested to start with fuel injection cleaning and valve adjustment. Fuel injection and throttle body cleaning was performed. Once gasket arives, valve cover gasket replacement, valve clearance check with necessary adjustments (assuming I don't have to deal with #6's) will be performed. I'll test compression again at that point and post results.

I've become a bit paranoid about Head Gasket failure, even though she's been well serviced and runs very well. I passed the bubble test, but I do seem to run a bit on the warm side, as my temp gauge is always a frog's hair above horizontal. Hopefully once I get my new fan clutch and thermostat in, the running temp will drop. I'm hoping that my compression does not point to head gasket problems, no spiking drop in #6, so that's good.

Thanks for any thoughts on the matter
Perk

 

[Cruiserhead05]

Perk, i dont have any answeres or real thoughts on the matter as i am not the most educated on engine compression numbers. I hope to maybe have a test done on mine soon as it has 240k miles but still runs so strong and has tons of power for the I-6 and that much mileage, granted i have done the Head Gasket.

 

[robbie]

The main thing is that the numbers are with in 10 psi of each other. the guage could be off, the test not done the same as the next wrench. Not all guages read the same as the next guys. As for worrying about the HG, either do it and have piece of mine or stop worrying about it. It it goes then fix it. later robbie

 

[sixsracing]

What Robbie said.

 

[elmariachi]

I'm wondering about compression. At a prepurchase inspection done a few months ago, mine measured 1-165, 2-155, 3-160, 4-155, 5-160, 6-165. If I remember correctly, factory specs are 170. I'm not sure how to interpret these? How do these numbers compare to yours?
Perk

For what its worth, I tested this new 40th Ann I bought a month ago (as I am contemplating the blower) and mine was 1-165, 2-165, 3-168, 4-165, 5-168, 6-168. I used a Snap-On tester. 128,000 miles.

Jim

 

[ultimauk]

FWIW, my 93 with about 300k had a compression test of 165 - 180 psi. probably a fluke compression tester or carbon build up.