What is the original plug specified for the 69 L89?
Thank you,
Verle
Thank you,
Verle
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R43XL shows for 430hp (L88) but not for...
435hp cars, according to the 1969 Chevrolet Engine Tune-up Spec Sheet. However, the L89 version of the 435hp HAS to (also) use the fully threaded R43XL in the aluminum head. The R42XL is recommended for cold (racing) applications. -
R43XL for 1969
The plugs used on the cast iron heads were only threaded 1/2 of the distance into the head. The XL style is the one you must use. Starting in 1969, they began using the resistor plugs. The 42 heat range is too cold for the street.
To make a long story short, use the R43XL.
Good luck,
MarkComment
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for street use R-45XLS will work fine
because the extended tip is cooled by the fuel wash and it would be more like a R-44XL in heat rangeComment
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Re: for street use R-45XLS will work fine
Clem,
I am concerned the extended tip would hit piston domes.
VerleComment
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Re: for street use R-45XLS will work fine
i have used extended tip plugs in BBC engines with 13:1 CR which have a bigger dome than the 11:1 engines. if you do not feel comfortable doing this use 44 without the extended tip because the 43 are too cold for street driving. another trick i have found about BBC street engines is after driving around town when you hit the highway take the RPMs up at part throttle to clean the plugs before WOT blasts because full throttle will cause the deposits to "bake" onto the plugs and it will cause misfiringComment
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