D-

Well-known Member
What was the reason early H's did not have a spark plug cover.
I think I've seen they were first installed on SN 7919.
Earlier H's than that (all I've ever seen) had the threaded holes
in the frame.
 
My guess is that they didn't have the tooling ready in time to have shields for those earliest tractors. You are right about the serial number (7919) - that tractor (warehoused on 6 June 1939) was the first to have spark plug shields from the factory. This was described in Field Service Bulletin FSB 100-S which also mentioned that shields would be available for all “H” tractors in the field at no cost to tractor owners. So that statement, along with the fact that the tapped holes in the frame for attachment of the shields started at the beginning of tractor production makes me think that Deere just didn't have them in time for some reason.

Incidentally, the new John Deere Engine and Tractor Museum has the actual drawing of the left hand spark plug shield. Unfortunately, I forgot to check the date of the drawing....
 
Don't know this, so it's time I ask. I see many JD's with various sorts of shields / covers / protective things for those spark plugs. I assume to prevent things from snagging the plug wires or breaking the plugs. Over many many years. Why didn't JD just relocate the plugs to the top - vetical position on the block, eliminate the problem?
 
The model "D" did have the spark plugs on top - but - it also had the camshaft and push rods below the cylinders. When the model "A" and the rest of the Waterloo two-cylinder tractors came out, the camshaft and push rods were moved to the top of the cylinders which would have made it a problem to get the plugs into that area.
 
Thanks,
I'm thinking it was a price thing since holes were in frame.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top