[AT] 1935 Testing progress.

[Dean VP]

The later JD All Fuel JD B's, which had higher HP, had a compression of 70psi. Haven't found a reference for the earlier JD B"s.  But it surely wouldn't be higher than 70.  The difference between cylinders of 7 1/2psi is pushing the limits of acceptability.  These tests were with the tractor cold. The compression test is supposed to be run when the tractor is a running temperature. The next test to run is the manifold leakage test. Then I probably will install the magneto and carburetor and get it running so I can do a high temperature compression test.  I may just pull the tappet cover and see if the lash is set right on the valves first. Now that I have the right tools to do the testing I Can make some progress. 

Dean VP
Apache Junction, AZ

-----Original Message-----
From: AT <at-bounces at lists.antique-tractor.com> On Behalf Of Dean VP
Sent: Tuesday, November 24, 2020 7:43 PM
To: 'Antique Tractor Email Discussion Group' <at at lists.antique-tractor.com>
Subject: [AT] 1935 Testing progress.

Was able to get the 1935 JD B out of storage and since I had the carburetor and magneto removed during the winter storage we just pulled it to new location for the winter. Since we were pull moving anyway I asked my friend to pull me in gear  about the distance of the two blocks with the plugs out to get the oil pressure built up for the compression pending compression testing.  Then hooked the compassion tester and 7/8" to 154 MM adapter up and had him pull me a 100 feet or so in gear and tested compression on each cylinder.  Thew results were not as expected.   Got about 62 1/2" psi on the left cylinder and about 55 psi on the right  cylinder.  I expected a much larger difference between the two.  Not sure what it should be but sone reason I expect 70 psi but I don't remember where that came  from.  But the 7 1/2psi difference by itself tell me I need to tear into this tractor.,  I don't think.  Tomorrow I can do the manifold air pressure test.  If I can complete that. He results of that test will determine what I test next,


Dean VP
Snohomish, WA 98290
"Socialism is a philosophy of failure, the creed of ignorance, and gospel of envy, its inherent virtue is the equal sharing of misery."
..Winston Churchill...