Thread: Spark Plugs
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Old November 10th, 2024, 05:30 PM
Prowbar Prowbar is offline
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Default Re: Spark Plugs
I am running the 478 on propane mostly. Propane burns hotter meaning you need colder plugs. The porcelain on the AC R44XLS plugs in the 305 and 478 was very white. I switched to R43XLS plugs and they are still on the hot side, but a little better.

I am now running NGK BRP6ES plugs (same heat grade as the 43) and I like the NGK plugs better. Can't say I noticed a smoother idle or anything.

I was running the HEI ignition but switched back to points. I find more joy in keeping things original/OEM than aftermarket stuff. No difference in idle or cold starting for me. Still using the stock coil with the resistor wire.
Last edited by Prowbar; November 10th, 2024 at 07:24 PM. Reason: typo
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