Inliners International Forums General Discussion Engines compression test

I have a 1964 250 that I just pulled from a friends truck and was hoping to use it. I just ran a compression test on it and here is the results.

#1 85
#2 85
#3 85
#4 60...w/oil 75
#5 82
#6 82

I was told if you needed to put oil in the cylinder and it reads a higher number then it is a good indication that you have bad rings in that cylinder. All the other cylinders read about the same. Am I looking at a new ring job, or could it be more? I was just turning the engine over with a battery on the engine stand...so that might be why the other reading are lower than 90.

could also be a valve not seating. tom

with all the others so close i would bet on a valve. pull the head and check out the valves first.

Bob is correct about the 10# difference (with oil).

There's a ring issue in #4 because the oil brings it up 15#.

Compression tests should be done with the engine @ operating temp. They would be around 100 on the ones that reach 85 cold.

If; there's no oil in the water or water in the oil, you have an "overhaulable" engine there.

Or; you could rebuild it.

Or; you could just change the rings in #4 and a 'valve job'.

Good luck.