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[GMCnet] spark plug questions, please [message #133508] Wed, 06 July 2011 12:56 Go to previous message
Ek_Lektro is currently offline  Ek_Lektro   United States
Messages: 167
Registered: March 2011
Karma:
Senior Member
Well, its been a while.... and its definitely time for a new set of plugs!
not sure which ones to buy...
When i pulled a few of the old ones out, the gaps on them ranged from .45 to .70...
no wonder it was running crappy? (Can the gap change that much over time?
or is it more likely that the previous mechanic botched the gapping job?)

So i checked the cross reference on my GMC Motorhome International Parts Interchange Index (circa 1998!)
and for my '76 455, these are all listed as compatible:
AC R46SX with .80 gap
Bosch WR10FCZ with .80 gap
Champion RJ18YC6 with .60 gap
AutoLite 847 with no gap spec listed

in this same index, i can see that for other GMC years, the recommended gap can range from .40 to .80...
Considering that this '76 engine was supposedly rebuilt back in 2002,
is it safe to assume that they rebuilt the same engine, and that the same spark plug specs apply?

Bottom line, what's the conventional wisdom say about best plugs to use,
(and/or which to avoid), and of course, the recommended gap spec?

OK, thanks much for any info....
Greg
SolarSonic / LosAngeles

PS: No surprise, I've noticed that some of the parts numbers in this '98 index are starting to become obsolete
at AutoZone, etc. Wondering if this is mainly due to the parts in general getting more scarce over the years,
or if perhaps its just time for a new Parts Interchange Index?
Anybody know if GMCMHI has been keeping the parts index up to date?
If so, i think it'd be time to subscribe again... $30 or so....?
Sure got my money's worth out of the last one.. LOL...!


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