John Deere "A" Valve and Flywheel timing
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Thread: John Deere "A" Valve and Flywheel timing

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    Question John Deere "A" Valve and Flywheel timing

    I have an Electric Start JD "A" that I started restoring a few years back ( s/n 533xxx), and I went through the engine and had to replace the crankshaft. I replaced it and made sure that the crank and cam timing marks were in index. The crank shaft to flywheel mark was just (looks to me) like a chisel mark so I lined that up with the mark of the flywheel. I rolled the engine over until the flywheel impulse marks are aligned with the timing mark on the gear case as prescribed in the IT manual and the no 1 piston was up on top dead center and both intake and exhaust valves were closed on compression stroke. I adjusted both valves to .021 cold and now here is where it gets strange. As it says in the IT Manual roll the flywheel forward until the exhaust valve has .000 clearance with the tappet and the L.H Exhaust Open mark on the flywheel should be within 1 (one) inch of the timing mark on the gear case, I did this and the L.H.Exhaust Open mark is setting at the 6:00 position.
    My question is: Is the L.H. Exhaust Open mark on the flywheel supposed to be aligned with the mark on the gear case (or within 1 inch) when the exhaust valve is all the way open or just when the lash on the valve is .000?

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    Quote Originally Posted by Paul P View Post
    I have an Electric Start JD "A" that I started restoring a few years back ( s/n 533xxx), and I went through the engine and had to replace the crankshaft. I replaced it and made sure that the crank and cam timing marks were in index. The crank shaft to flywheel mark was just (looks to me) like a chisel mark so I lined that up with the mark of the flywheel. I rolled the engine over until the flywheel impulse marks are aligned with the timing mark on the gear case as prescribed in the IT manual and the no 1 piston was up on top dead center and both intake and exhaust valves were closed on compression stroke. I adjusted both valves to .021 cold and now here is where it gets strange. As it says in the IT Manual roll the flywheel forward until the exhaust valve has .000 clearance with the tappet and the L.H Exhaust Open mark on the flywheel should be within 1 (one) inch of the timing mark on the gear case, I did this and the L.H.Exhaust Open mark is setting at the 6:00 position.
    My question is: Is the L.H. Exhaust Open mark on the flywheel supposed to be aligned with the mark on the gear case (or within 1 inch) when the exhaust valve is all the way open or just when the lash on the valve is .000?
    I would just like some help and advise from someone that has had the experience of timing this type of tractor so I can be confident that it is right before I start it so I do not have to take it all apart for a do over. It is hard to find anyone with the experience on these old Johnnies anymore. They are all DEAD.
    Superglidesport and BigJim55 like this.

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    tlock0331's Avatar
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    they arent ALL dead...but i will tell you, its been quite awhile since ive have had to deal with pulling the flywheel and crank and completely retime one. I have also never owned and IT manual. Deere still makes the service manuals for the ol A's and B's etc. and they are the same price as that IT...

    So i have been trying to think this through..how many revolutions did you go on the flywheel before the LH impulse was at that 6:00? The 2 cylinders dont fire quite like a person would think, I gotta be honest, i would have to go back and roll one over and watch again. It doesnt seem like its a true 720 deg on the next compression.

    i dont do it often enough on a gasser to sit here and give you a 100% correct answer, i would watch the valves, pistons, and listen for the RH side impulse and go from there. good thing is, even if you are way off, theres plenty of room in there to not hurt anything rolling it over and seeing where you end up.

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    I didn't roll the flywheel all the way through, just enough to take the backlash out of the L/H exhaust valve like the book says. I will get some help to do this because it is hard to do with the starter in place and trying to watch the piston and valves and the flywheel marks all at the same time.

    I talked with a "Two Cylinder Guy" that works for John Deere in our area and he was going to call me back, but never has. I really appreciate your feedback, there aren't too many guys left out there that you can talk to to get first hand knowledge of these old tractors. I grew up with my dad's 1944 "A" and sat long days plowing, springtoothing and raking hay with that thing. It was the main tractor when we first moved to the farm in 1945. I was 9 years old before I could stat it by myself. My older brother used to just throw a chain on it and drag me a few feet to start it with the "B" (it was electric start) so we could get back to plowing after lunch.

    Thanks again, and stay tuned it will be a couple of days before I get back to this when the snow melts.
    JDB44 likes this.

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