Gary from Iowa
Member
Is it a normal rule that the lower the number on a series of spark plugs, i.e., D-21, D-16, D-14, D-9; the cooler the plug? I have a DC-3 that has 4 1/16 dome pistons and some other items. Put it on a Dino after getting it all back together and run it for a little over a hour. It is tighter than I like, really have to pull on the crank. Converted to 12 volts and will start with starter but it labors. Runs good, but I am afraid it might seize if I pulled it hard. Was told by a old mechanic, two years younger then me, to run colder plugs in it until it freed up a little...Make sense or just an old tale. Oh, piston clearance, mains, rod clearance and end gap on rings was all checked during assembly for proper spec. Thanks.