JD 420T Engine Timing

Keith Calhoun · Jul 18, 2016

My father is rebuilding the engine on his 420T 2 cylinder JD. He says he thinks he does not have the engine timing set correctly, something about timing the oil pump to the crank/cam, which will set the timing for the distributor since the distributor is driven off the oil pump. Can some one walk me through what the steps are to line up timing marks ect during the engine overhaul process for this tractor? Thanks for he help. Keith

MikeinKy · Jul 18, 2016

Remove the distributor, install the oil pump with the slot about 15 degrees clockwise from straight with the block. This is the best way I can explain it. If you have a shop manual, it tells you to use the JD service tool to aline it. I think it is not available. Also, the slot is not centered. You need to have the narrow side out. Probably need to measure it with a caliper. There is only about .060 offset in the slot. I measure the slot and mark the narrow side with chalk or something so I can tell easy which side it is. The slot is offset so that the distributor will go in one way. It won't go 180 off. Get it running and fine tune the timing by turning the distributor like you would any other engine. Hope this helps. I bought a 420 a few years ago that wouldn't run. I checked things out and it appeared to be a freshly overhauled engine, so, I pulled the distributor and got #1 piston up on compression and it was about 2 teeth off. Timed it and it ran good.

JD 420T Engine Timing

Keith Calhoun

Member

MikeinKy

Well-known Member

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