Andy, not to scare ya, but I've always went by a max of 15 lbs between min & max to indicate engine health. That combined with oil on the plugs of the weaker cylinders indicates a ring issue to me. Might want to do a leakdown test next to see how they hold pressure.

Cylinder pressure is dependent on cam timing and compression, main thing I look for is equality across all the cylinders.

 

10 percent between highest and lowest # is always been acceptable in my book. Hope this helps. Don

 

Thanks for the input guys. I retested last night. This time I came up with:

1 - 125
2 - 125
3 - 127
4 - 130
5 - 127
6 - 133
7 - 125
8 - 125

Now I'm really confused This is such a simple operation, I MUST be screwing it up somehow :clonk:

I'm going to try it again this evening, but this time I'll try squirting a little oil in the cylinders.

Andy

 

Are you using a compression tester that threads into the spark plugs or one that gets pressed in. I used a press in type gage and was getting strange readings. Bought a new thread in type gage and no problems.

Just a thought.

 

Are you using a compression tester that threads into the spark plugs or one that gets pressed in. I used a press in type gage and was getting strange readings. Bought a new thread in type gage and no problems.

Just a thought.

I had a cheapy that you just HOLD in the hole while someone else cranks. After looking at it for 0.2387413 seconds I tossed it in the trash and "rented" one from O'Reilly's tool rental deal that screws in.

Andy