I'm running a 1966? Chev. 327 W/ I believe mid seventies unleaded heads, mild cam and a Mallory Unilite electronic distributor and Mallory coil. I want to make sure I am using the right sparkplug. At the moment I'm using Autolite AP 145. I'm not sure if I should match plugs w/ engine year or year of heads? The engine is installed in a 2600# Model A Coupe. Thanks for any imput.
X2 for me! got a 1964-65 283+.030 with 461 heads that will be running an edelbrock 5-600cfm carb and an old mallory double life dizzy with a MSD 6al pushing the spark. a good source for old looking wires that would work good with this ignition setup would be excellent as well!
AC-44's if you have flat tops or whatever cross-references in your preference. (What they came with originally)
I think you are going to have to use the spark plugs for the heads . Does your heads use the large spark plug or the smaller one ? I early Chev engines used the large spark plug , right ? You will have to go with what fits the head first . Now if both are the same size then go with the year . Hope this helps . Retro Jim
Your going to have to use the plug for the head so the reach and threads are correct. Then experiment with the heat range so it burns best for your engine combo.
Probably the autolight AR135ish? In hot weather you could use the 134, cold weather up to a 136. These series of plugs have 5/8 wrenching and retracted tip/electrode. NKG crossover would be 5673-6 or -7; champion would be V63C but they have some screwing numbering and a hotter range might be an entirely different type of plug. The colder the plug the cooler the engine, typically you'd choose the coldest plug but still be able to putt in traffic without fouling the plug (in which case you'd go 1 step hotter). The heat range is the plugs ability to deal with heat in the combustion chamber and has no reflection on the electrical properties.
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