Geeeeez, another PPI ?
 

My PPi just indicated 150 in all cylinders. Now I'm hearing you guys talking about 170 and 175. 20-25 diff? Whasup with that????:confused:

from what i learned it isnt the numbers, but the consistency.

Yah, but I'm not constipated! Oh,,,um,,, never mind

also depends on the year and engine model. And how well the test was done.

81 SC. Should be the same as 80 thru 83,,,right???

I would be happy with 150 all across.

Absolute numbers are practically meaningless. Here is only a few factors that can change the absolute number tremendously:

air pressure
temperatures (outside and engine)
battery power
starter
what's with the other spark plugs?
throttle open or closed during test?
the compression tester used (none of them are absolutely calibrated).

So, you see, any of the above factors can get you lower or higher than numbers you read on the board.

To clarify: It is important that your numbers are within 10% of each other. Take your highest number and subtract 10%. If all other numbers are within that range, you are okay.

George