I have this '66 C10 truck that I just got. 327 that supposedly is rebuilt original. I haven't run the numbers yet. If you are bored the number pad has K1129YHY on it. Anyway.. I went ot buy plugs for it and the dude gave me R43TS delco plugs.. They use the 5/8 socket. When I went to go change them out the truck has RJ12YC Champion plugs in it that use the 13/16 socket and a crush washer.. So is it even possible that someone installed the wrong plugs? will the lager plugs seat on a head made for the small ones? If I need 13/16 style plugs, which ones should I get?
The AC 43's you got are too cold and will foul out, you need an AC 45 or an AC R45 if you have HEI or like a clear radio. What Yobaby said sounds good too, but I don't know those numbers, just the AC. The R stands for resistor and cuts down on radio interference. The 43 is the temp, a 45 is stock, a 46 or 47 is for an oil burning engine and a 42-43 is for a supercharged or nitrous fed engine. A 44 works good on long highway trips over 65 in the summer.
13/16" hex with gasket.(If the heads are early) That I can't help you with cause I can't see the #'s or the markings on the head. For the big plugs the recess should be about 7/8" in diameter and flat at the bottom of the recess. For the little plugs a recess just large enough to accomodate a 5/8" socket with a distinct taper at the bottom of the recess around the lead in of the plug threads. T.OUT
r45 ac plug with wire washer, not the r43 ts plug they are for newer tapered seats the regular r45 or r44 will work the higher the number the hotter the plug will be 13/16 plug socket with the right plug.
you need ac 45 or r45 like said above the "T" stands for tapered seat, you need the 13/16 flat seat with a gasket. all (i think) the 13/16" ones have the flat seat and all that have the tapered seat are 5/8". i think the tapered seat ones came in around 67 on cars (?). http://www.acdelco.com/html/pi_plugs_ident.htm
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