Hot Rods What spark plugs do you use in your high mileage sbc ?

As the title says what spark plugs do you guys use in your high mileage sbc ?


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depends what heads are on it...69 or older, or 70 or newer. R45S or R45TS.

 

High mileage, as in burns a small amount of oil?

 

Last one I ran used R45 T when I had points and swapped to R45TS when I stuck an Hei in it.
I didn't have the money for Fancy plugs then.

 

Yes it’s your typical sbc probably 100000 miles on it.


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In my garage 100000 is just getting broke in

 

I agree I’ve put over 200000 on a few


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NGK B6S, or XR4

 

Autolite 26

 

I run AC plugs. I don't recall the number on them. I got around 150K on the timex. I have always run the same plugs since it was fresh.

 

An extended tip plug would be my choice what ever brand you like. The extended tip runs hotter at low rpm and run cooler as the rpm goes up.

 

I had good luck with the AC Rapidfires gained about 2 MPG and the L79 cam seemed to idle smoother.

 

I have a little story on how bad I think AC plugs are: One of my best friends back out of high school had a 68 Camaro, originally a SS396 4 speed. He blew that up and built up a 307-I know-Anyhow he left it sit in the garage over one year while we had fun in his 58 Ford retractable. The next summer he wanted to get the Camaro out but it wouldn't start. He had just put new plugs in right before he quit driving it that year. But it didn't have any spark-I asked him if he had any plugs around. He replied, a bunch of old assorted plugs in that drawer over there. I found an old Champion that was all carboned up but the tip looked close to the one AC I pulled out. I cleaned it the best I could and put it in. Just for the heck of it I tried to start it and it started, didn't run very well though. I found like 4 more of those dirty Champions cleaned them up and the old Camaro was running much better. I've seen several other cases where they didn't run worth a damn. I'm a Mopar guy so I use Champions. I guess everyone has their own opinion. By the way, that 307 hauled ass!

 

Neat story. That would make me wonder what he did wrong with those AC plugs to make the the car not run.

 

Autolite 26...

 

I had that with Champions that came from a Gibsons store back about 1980. A customer brought then to me after a valve job no start put the old plugs in fired right up. The story going around was the Champion was selling there rejects through discount stores. I never had that happen with Champions from a parts house.

 

I even ran AC's in my harley sportster out of my 327. lol