compression test 73 chrysler newyorker 7.2 440
- Thread starter sidsnot
- Start date
Leeinri
New Member
A low compression 440 of that era should be anywhere between 120-160 PSI cranking pressure. At operating temp and all plugs out with throttle plates open. If it's cold subtract about 5 PSI. The main goal is you want all cylinders to be within 10% of each other to be a real good runner.
65sporty
Old Man with a Hat
Like Leeinri said, but I think you will see numbers closer to the 120 range.
There are a LOT of things which can affect ultimate compression for the test, including altitude and such. I was thinking the 8.2CR motors' spec was closer to 120psi, too. Rather than the "raw numbers", look at the spread of the numbers from high to low. One will probably be low as the rest are mostly close to the same. The compression test ONLY tests the seal of the top compression ring, not specifically the condition of the oil rings. Plus how well the total seal is, compression rings and valve seats.
There are some budget testers which are held against the spark plug hole, but the screw-in versions are the most repeatable and accurate way to do things. Especially if you're doing the test by yourself.
For further investigation, you can get a bore scope (a camera that hooks to your computer) to see what's really inside of the combustion chamber. Some even have memory of the video of the situation.
Please keep us posted on what you find.
CBODY67
There are some budget testers which are held against the spark plug hole, but the screw-in versions are the most repeatable and accurate way to do things. Especially if you're doing the test by yourself.
For further investigation, you can get a bore scope (a camera that hooks to your computer) to see what's really inside of the combustion chamber. Some even have memory of the video of the situation.
Please keep us posted on what you find.
CBODY67
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