It must be something similar to wanting to try a new unkown beer, but I apparently have a thing for different spark plugs.  Currently in use are NOS Atlas which are doing great.

Yesterday I bought 10 Prestolite #18F82, 18mm tapered seat plugs on ebay.  Does someone have a chart comparing these to Autolite 45/46s?  Also when approx. did the Co. stop making them.

(site locked up before posting and had to start over)

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Hi Mike,  I have an old Autolite catalog from 2000.  They show the Prestolite 18F82 crosses to an Autolite #36.  This is the same heat range as the 46, but the 36 is a non-resistor plug.  You can verify whether it is resistor or not with a VOM, measure the ohms from the center electrode to the top of the plug where the plug wire attaches.  A resistor plug will usually measure between 5K and 15K ohms.  Anyway they probably haven't been made since the 80's or 90's, can't say for sure.  So it is a standard heat range plug.  When I worked in the auto parts business, Prestolite had a reputation for lousy quality control.  Some of their plugs were so bad that you could hold the metal hex shell in one hand, and grab the porcelain in the other, and spin the porcelain inside the metal shell.  The engine combustion could just shoot out the gap between the two.  You may be lucky and they may be fine.  I admire you willingness to try something different.  Good luck, Nick Brann - K.C., MO

Thanks Nick I appreciate the info, and as a result they may just stay on the shelf as display paraphanalia.  Luckily they didnt cost much.  It brings up another question which I've been wondering about, i.e. resistor vs. non resistor plugs.  What are the indications for one or the other?  It seems nonresistor would be the best for street or most anything else, but I have no real basis for the thought.

Checked my ebay and had forgotton that also due to arrive is a box of 10 Motorcraft BSF82C plugs.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Hi Mike,  I didn't mean to scare you away from using the Prestolite plugs, they are probably fine.  As far as the indications for resistor plugs, most manufacturers used an R in the part number to signify resistor.  Example- Champion F14Y is non-resistor and RF14Y is resistor.  According to my Autolite catalog, however, the Prestolite 18F82 is non-resistor but their 18F6 crosses to the Autolite resistor plug, #46.  But I don't have a Prestolite catalog, so can't say for sure.  The best way to check is to use a VOM as I said earlier, from the center electrode to the tip at the other end of the plug.  The Motorcraft BSF82C is a resistor plug, the S stands for suppressor.  Newer vehicles require a resistor plug because they actually idle better and produce lower emissions.  Crazy, huh?  Don't waste a lot of time looking for non-resistor plugs for a street-driven car, any difference will be negligible.  Hope this helps, Nick Brann - K.C., MO