So it's no mystery I am knee deep in a rebuild but somthing still has me thrown off. On my 95 3.0 with 240,000 miles the "good" cylinders seem to read very high for a 9.0 to 1 compression engine. Yes all gauges very however I have tested this gauge on a few other engines and here is what I came up with.

3VZE 240,009 miles with 9.0CR tested at 80 degrees averaged 180 psi
Honda B18B 140,000 miles with 9.3CR tested at 30F averaged 175 psi
4.7HO rebuild 1000miles with 9.7CR tested at 50F averaged 185 psi

I am only taking into account the 3 good cylinders that have been consistent but with the air being warmer and the lower factory compression I would think 9.0 to 1 would be around 160ish.

Any body else tested their compression or that can shine some light onto this.

 

A man with a watch knows what time it is, a man with two watches is never sure.

If you want to be truly flummoxed, try using two different instruments.

So many different variables, could well just be carbon on the piston heads.

Get those heads reworked and go!! No worries.

 

Lol well said. Dropping the heads off today in fact.

But back to the subject. For the guys who have done compression tests on healthy motors what are you typically seeing.