In Reply to: Spark plug wrench? posted by Andy B (MI) on March 20, 2016 at 20:31:14:
OK, finally got the camera working again so here are some ideas...
In order of appearance:
81A-17017 -used from June 1939 thru August 1939. 11/16 6-point box end and 13/16 open end.
01A-17017 -used from August 1939 thru April, 1940. 11/16 12-point box end and 13/16 open end.
01A-17017-B -used from April, 1940 through all of 8N production. 11/16 12 point box end and 13/16 12 point box end. This is the 'suitcase handle' wrench.
Part number unknown, but this is an offset SEARS brand 13/16 12 point box end and 7/8 12 point box end I have had in my toolbox since the 70's. I do not recall where I got it but probably SEARS itself. Only shows a logo "BF" and JAPAN forged on. It works
perfectly for N-Series Tractor spark plug R&R so I keep it in my tractor toolbox now.
Not shown is the 2C-17017 stamped steel socket and handle wrench that was issued wit h the new NAA Model with the overhead valve engine.
A 3/8 drive socket wrench will work too as shown below, just try to use a 6-point deep well socket. Always use compressed air to blow out the plug wells before removing your spark plugs so dirt and debris doesn't fall into the holes when the plugs are removed. If air compressor isn't available, keep a small 1" paint brush in your tool box to clear debris with. Never overtighten the spark plugs. The original FORD spark plug spec was to use the CHAMPION H-10 plug. Since then, CHAMPION has a better plug, the H-12, also sold now as the 512 number. The AUTOILITE 437 is another popular N-Series Tractor spark plug. I've used both the H-12 Champ and the AL 437 both equally with great success and have no preference for one or the other. Often it depends on what my local auto supply store has in stock when I go to buy them. The dimension of both plugs AF (across flats) is 13/16 (.8125"). Finally, the Ford Tractor spark plug thread size is 14mm with a 1.25mm thread pitch. DO NOT use any other tap if you are trying to chase the head threads. If you don't have one, try an old plug that has been cleaned up. Always start the plug by hand and screw it in as far as it will go without forcing it. Check the gap too as they are never gapped the same out of the box. N-Series Tractor spark plug gap is spec'd at .025" - .028" and points at .015". Be smart -use the right tool for the right job and be safe...