Topic: Flathead Diagnostic TestIng


DJ    -- 10-02-2020 @ 6:19 AM
  I have had my dads 51 Ford custom, Flathead V8, for 5 years now. So far, I have been able to perform the minor repairs needed, with the help of this forum. I’m wanting to learn more about doing diagnostics and adjustments on the engine, starting with a compression test. Car is running fine, just curious what compression is. Few questions I have that I can’t seem to find answers to online. Do I remove all spark plugs or test one cylinder at a time? Do I need to stop fuel flow or spark? If so, how? Thanks guys.



TomO    -- 10-02-2020 @ 7:40 AM
  Buy the Service Manual for the 49-51 Fords. It has the best diagnostic information for your car. Another book to look for is the Lincoln Mercury Master Check Complete Engine Diagnosis. It is more specific to the engine and details the tests better.

To do a compression test:
Buy an accurate tester and a remote starter switch
Make sure that the battery is fully charged
Drive the car to get the engine up to operating temperature
Remove all spark plugs and open the throttle all of the way
Connect the remote starter switch to the starter solenoid
Install the tester into a spark plug hole and crank the engine with the starter at least 4 compression strokes. Record both the first stroke and the last stroke readings
Record the reading
Move the tester to the next cylinder and repeat the test using the same number of compression strokes for each cylinder.

The readings should all be within 15 lbs from the highest reading. If you have cylinders that are more than that, add about a teas spoon of oil to that cylinder and repeat the test. If the reading improves to within 15 lbs, the rings are worn, if it does not improve, you have sticky or burnt valves.

Tom


nelsb01    -- 10-02-2020 @ 2:40 PM
  The 1949-50-51 Ford Passenger Car Shop Manual is what Tom is talking about.
It has a green and yellow cover and is about 5/8inch thick.
There currently are quite a few for sale on eBay (including on DVD). It is also available on Amazon.

Hope this helps.


51woodie    -- 10-03-2020 @ 11:39 AM
  Rock Auto also has them.
https://www.rockauto.com/en/catalog/ford,1951,custom,3.9l+239cid+v8,1339534,literature,repair+manual,10335



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