JD 70 flywheel???

Anonymous-0 · Mar 18, 2013

Took the flywheel cover off a 70. The flywheel had no timing marks like you usually see on a two cylinder flywheel. The crank also had a heavy steel square about .5" thick, threaded on end of crank to keep flywheel tight. Then had wire wrapped around the corners of the steel square and run through a hole in the bolts that clamp the crank down. Would the steel square be from the factory and how would you time the tractor with no timing marks on flywheel?

Loosehandle · Mar 18, 2013

That sounds like a taperlock flywheel,dont take off unless absolutely necessary.
For the ignition timing, put a good load on it and adjust by ear.

Hugh McKinney · Mar 18, 2013

I had the same question about four years ago when I inherited my Daddy's JD 70, since he was deceased, there was no one around to ask. I finally figured out that on the flywheel cover, there is a small "viewing cover" that you can remove, and looking through that small hole, you will find that there is at one point, a "bump" on the flywheel about the size of the hole in the cover. You take some chalk and mark the bump to make it easier to see with the timing light. Once you have it started, or at least rotating, with the timing light connected to the left side (flywheel side) cylinder spark plug, move the distributor one way, then the other, until the chalk mark "fills" the hole in the cover. I used different colors of chalk to denote BTDC and ATDC, because at first it was so far off that I couldn't see my chalk mark at all through the viewing port. Good luck.

wilamayb · Mar 19, 2013

I wouldn't suggest setting ignition timing by "ear" on a 70. If it is the least bit advanced at startup it will snap the starter nose when it kicks back. They can be expensive for a 70 since so many of them have been snapped.

I say free up the advance mechanism and set the timing with a light.

Anonymous-0 · Mar 19, 2013

If you're used to looking at ABDG and H series the timing marks are not on the flywheel face. They're on the rim to be viewed through the hole under the pear shaped "flap with one screw in it" up on the forward top of the flywheel cover.

What you describe flywheel wise sure sounds like a taper lock as Loosehandle said. It too should have marks on it. My taperlock does though my tractor is a Diesel.

Like Wilamayb said though... I'd NOT tune by ear unless it's a modified engine! There yer on yer own! They prescribed a 10° after TDC (static timing) for a reason on the gas & LP models. That reason is at least partially starter parts!

After that start it up & you SHOULD see it running 15° advanced at 1000 & up! Much more than that & they'll knock right soundly under load.

Make sure the advance works right in the distributor! If it's -10° static and reaches +15° at a thousand, the mechanical advance is working as it should.

Hope that's helpful.

JD 70 flywheel???

Anonymous-0

Well-known Member

Loosehandle

Well-known Member

Hugh McKinney

Member

wilamayb

Well-known Member

Anonymous-0

Well-known Member

Similar threads