I have a 63 327/340 engine currently using AC R-45 plugs. Would appreciate advice regarding the appropriate plug to use for this engine including whether R-45S plugs are suitable. Thanks.
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Re: Spark Plugs
Originally recommended AC43 plugs for severe duty/towing/off road; AC44 plugs for normal driving; AC45 plugs for city driving.
Most people use R45 plugs for normal use, although many have had success with R44 plugs (which are no longer available) R43 are definitely too cold for everyday use.
I think that you should be OK with extended tip plugs. I am not certain of the exact clearance from crown to electrode, what with the possibility that the engine might have been modified somewhere in its life. Even with its original steel shim gasket(s) in place, there was a fairly wide variation in deck heights from the nominal 9.025".
If it were me, I'd measure with a piece of clay attached to a standard 45/R45 plug's electrode before installing R45S. -
Re: Spark Plugs
just install the "S" plugs with the ground electrode at the 8:00 o'clock to 4:00 o'clock position and nothing will hit. mark the insulator with a magic marker where the ground electrode is located and if you can see the mark after installation you are good to go. DO NOT use a lead pencilComment
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Re: Spark Plugs
Unless the block has been decked and a thin gasket is installed there won't be any interference with extended electrode plugs. You can measure gasket thickness with a feeler gage at the corners of the head-block interface.
Flint installed two .018" gaskets on all '63 SHP/FI engines.
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