I haven't seen these before, are they original from the 1930s, or are they reproduced? I think R45 is suggested replacement?


My plug wires have 90* metal ends at the plugs, no boots covering the metal connectors, is that original, or as original?

Thanks,
Doug

The AC numbering system changed, I believe from 1936 to 1937.

My Pontiac used K7 originally, and I thought that crossed to AC-45, although references to this older AC numbering system are very hard to find. I cant remember if K9 is hotter or colder than K7.

Others around here will know better than I what to use in a Chevrolet today. If you aren't going to use those K9 plugs, don't throw them away. Someone will need them for sure.

Oh, i will keep the plugs,as they seem correct for the year. Looking to run easier to find stuff for general driving. I also need to find a copper nut that connects the Pos batt cable to the starter. the copper nut and washer that was with the plunger, was replaced a steel nut when i had the starter rebuilt. :(

Doug

I have been using AC LM-46 lawnmower plugs in the Pontiac. They are one range hotter than the AC-45 that seem to be listed in the place of K-7 after 1936. There has been no indication that they are too hot. I am quite happy with them. K-9 is hotter than K-7 IIRC, so you might be able to get away with that as well.

LM-46 are non-resistor, have a short insulator, and an unplated base, much like the old K-series plugs. It looks pretty good from 10 feet, and is the best looking thing I could come up with that is readily available to just buy and use up.

The heat range of a spark plug depends how the car is driven and the air/fuel ratio of the carburtor and the timing.