L-78 Spark plug choice

[firez]

While we are on the spark plug subject,what about a 1968 302 Z28 plug ?

[Chris396]

What about the 842 aluminum heads?

[Mr. Chevy]

I even run the NGKs in my jet ski which is a two stroke motor. never had any foul yet!!!

Rich

[Chevy454]

firez: the Z28s use the XR5 plug I believe.

Chris: if I'm not mistaken, the 842s use the R5671 also...but not sure on heat range? Maybe go colder (like -9 or -10?), but maybe Sam or someone else familiar with the alloy stuff can jump in here.

Note to self: make NGK plug crossover sticky post...

[firez]

Thanks for the Z28 plug advise.

[Dog427435]

I thought I had an NGK cross ref - but I can't find it. This might help though - you can cross ref your AC to Champion, then back check the Champion number to NGK.
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[Verne_Frantz]

I believe the Champions used to be preferred by racers because you could read the heat bluing color on the shinny threads. It's hard to get a true reading on the porcelain on a fresh set if the car is running good. (that's my feeling) but my racing buddy likes to put in a fresh set then pull them at the top end of the track before driving back to the pits. I guess I shouldn't argue with his wisdom.

Verne