Using a timing light on JD 620

chas036 · Oct 8, 2017

The service manual for my 60 says if using a timing light to set timing, then set the timing at 20 ATDC at fast idle. Is this the same for a 620, and 730 and Model B and A? All these have distributors with electronic ignition.

Bob · Oct 8, 2017

20? AFTER TDC???

David G · Oct 8, 2017

I am not sure about the 20 degrees, but should be BTDC, not ATDC.

John T · Oct 8, 2017

I agree Id think its more like 20 BTDC ??? The fact it has an elec switch or mechanical points shouldnt affect where you time it. If its engineered to fire at 20 BTDC it dont know or care if the coils current is switched with points or a solid state device, just time it so it fires then

John T

erskine2017 · Oct 8, 2017

Initial timing is set with the tractor idling as slow as it will run. Spark advance timing is set at wide open throttle and is usually 20 degrees for the number series tractor(propane may be different). For some reason a model 60 is slow initial timed at 5 degrees after top dead center and 20 degrees before top dead center at full throttle. The later number series Waterloo tractors are timed at 0 degrees which is top dead center at slow idle and 20 degrees before top dead center at wide open throttle. The Waterloo number series have markings on the flywheel and a little port hole that opens on the top of the flywheel cover. The letter series(with the exception of the last year(1952) just have a mark for initial timing. You would need a protractor to make a mark for advanced timing.

Using a timing light on JD 620

chas036

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Bob

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David G

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John T

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erskine2017

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