In article , Robert Kubichek
wrote:

Try this link, it show that the Bosch W7 BC plug as a cross reference
to the F7TC plug...

http://www.trantek.com/file/plugs.htm

Once you know the Bosch, you should be able to cross reference it to the
US plug makers....

Bob-

Thanks for the tip. You were apparently more successful than I at finding
data on the F7TC.

Using the Bosch W7BC number with a search engine, I found the Enker web
site, that had a cross reference between several companies. Their list
also includes some dimensional data. Unfortunately the W7BC plug has only
a 1/2 inch threaded "reach". The F7TC has a 3/4 inch thread, if I
understand what they mean by reach. (The Bosch W7CC and NKG B7ES are
plugs that fall in this category.)

The plug is gapped at 0.030". Thread diameter appears to be 13.7 mm, but
I think it is within tolerance of the common 14mm. The top electrode
appears to match a 36 tpi thread guage. An 8-32 nut doesn't quite fit. I
think it is a metric thread, 3.5 mm OD with a pitch of 1.4 or 1.5 mm.

I measured the DC resistance between the top electrode and where it comes
out the bottom. The reading was around 2 Ohms, but that could be the
result of contact resistance. I assume it is not a resistance-type plug.

73, Fred, K4DII