Compression Test

Can anyone run me through how to properly do a compression test on my other 1968 Ford 2000 gas and what psi I should be seeing. Thanks
 
Book says 115-150 psi.
25 psi max variation between cylinders.
All plugs out. Throttle wide open. No choke.
Good battery for max cranking speed.
Best to buy a decent compression tester that screws into the spark plug hole and not a cheap hand held one. Decent one will have a shrader valve to capture the reading.
 
In addition to what Ultradog posted, crank it over five or six turns
before checking the reading and recording it. I like to test them in order.

Then do a wet test. Add about a tablespoon of oil to #1 and run
the same test, record the reading next to the original one.
Do the same with the rest of the cylinders.

It does make a bit of a mess, but if the readings are low and they
increase significantly it could point toward weak/unseated rings.
If they don't increase significantly, valves or their adjustments.

This is a bit of an over-simplification, there are other indications as
well, but it covers the basic tests as I run them on my machines.
A leak down test is also a great test.
 
You are asking about a test that you have a reason for running. You may not like your test results, especially if the adding oil and retesting gives you the indication that you have worn rings in need of replacement.

You might do as I did and run some snake oil through the fuel and crankcase for a period of time, and give the snake oil time to do it's job. You may find that what you thought was a problem isn't a problem after all, or isn't bad enough to warrant a teardown.....BTDT, '63 2000D, in 2016, with the engine never having had a wrench on the engine proper, 3700ish hours, original proofmeter, still working.
 
So a little backstory and update...
The tractor had been sitting for years under a lean-to on the property I bought. Don?t know much backstory on it. Changed points, cables, plugs, gas etc and fired right up. Shortly after started getting smoke and oil out the breather. Worked it a little more and didn?t clear up. Maybe even got worse. Figured rings were bad or stuck. Parked it for a few months while I worked on some other tractors now just getting back to it. Did a compression test yesterday, #1-90PSI #2-80 PSI #3-85 PSI. Seems pretty low but I only dry tested it. I went out and bought some MMO and dumped it down the cylinders. I have heard plenty conflicting arguments of MMO vs ATF but just decided to bite the bullet and buy expensive stuff for the first round. Could hear the MMO dripping down into the oil pan from cylinders at first but after a few hours the cylinders seem to retain it. Rigged up a wand for my vac to suck remaining oil out of cylinders I?ll turn it over without plugs and then put them in and work it some more. Hopefully compression test will improve and then repeat the soaking process. I should probably try the wet test as well just to make sure it?s the rings. Really don?t want to do a ring job but prepared for it, worse case scanareo. Thanks for the responses.
 
like the others said, no choke, throttle wide open, 5 to 7 cranks then give it a looksee, Numbers per cylinder should be close.
A leak down test will tell you more than just a compression test. I do a wet test when I am testing away from the shop (in the field) The leak down is more thorough.
 
I picked up a machine with a similar unknown story, had the same hopes that it was stuck rings.... Ended up being incredibly worn rings and cracked pistons. That gas rebuild kit is 3x as expensive as the diesel kits. I was able to find it in .040" oversize which took care of the egg shaped bores.
 

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