Inliners International Forums General Discussion Engines plugs

I just installed an HEI unit in my '60 235. What plugs should I run now? I also converted over to a 72amp alternator from the generator/reg set-up if that makes any difference. The motor runs fine(actually way better)now even with the cruddy b carb. I am waiting for the 2bbl from stovebolt. Just wondering what you guys run in your 235's with HEI. Thanks...

I don't have HEI, but do have an MSD5 box. Made an incredible difference in idle smoothness, and now need much less choke when cold.

I am running AC R45S plugs, and think this is the best for street use. Much less prone to fouling than the R43S. I don't think adding a hotter spark means you should go to a cooler plug. In fact, in my opinion the best thing to run on the street is the hottest plug that doesn't induce pinging. If it doesn't ping with ideal timing curve, then a cooler plug is just going to set you up for more frequent fouling.

i always used the rapidfires until advance stopped selling it, now im using the ngk iridiums. nice plug but it is expensive. i think it was around 5 bux a plug.

Stay with the original factory recommended heat range but use a resistor type to be compatable with the HEI. Plug wires should be of the type for HEI units also. Taylor Spiro Pro are very good both in low resistance and stopping radio interference. They only come in sets for an 8 so you end up with 2 spares.
The HEI is less prone to fouling colder range plugs but on street engines both V8 and inlines I've found the normal heat range works fine even in slightly modified engines. To get the full benefit of the HEI gap the plugs at .045". You've converted to an alternator and that is a big boost over the original generator, something HEI's love.

Mike

I just made the same switch on my '57 235. The recommendation that came with the unit was AC R44SX. I had a time finding them, though. The counter jockey at one of the nationwide chains told me that AC was "phasing out" that plug and gave me a "suitable alternative" (R43S). Well, I couldn't gap the alternative to .074, so I took them back and found a couple of sets of R44SX's at a local parts house. It runs great with them.