Spark Plugs for Straight 8
A Technical Tip from Buick Technical Tips



Spark Plugs for Straight 8 -- It seems that old 320 CID straight eights seem to suffer from intermittent, slight idle miss that you don't feel, but can hear at the tailpipe, and it has always aggravated me. Whether caused by vapor leaks at the intake guides or any of dozens of other things that people have come up with over the years, it seems to be the nature of the beast. 

Something I have done that has helped much was to go to a hotter plug, something that Buick did itself around 1946 or so. I am using Champion #J18YC plugs and it makes a difference. (J-14 MM, 18 is extra hot, Y is deep reach and C is copper core electrode.) The big difference is extra-hot and deep reach to get the nose down into the chamber to keep it clean. It's a cheap fix to an annoying quirk of this machine. Don't use the R (resistor version), the non-resistor plug is available at your local auto parts supplier.

Jim Cox, #12125, November, 1989.

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