396 Spark Plugs... Correct AC P/N???

[James W.]

What is the correct AC spark plug that was used in 396 engine?

Thanks,

James West

[Clem Z.]

before the change to the short plug

R-45XLS

[greg janko]

Re: 396 Spark Plugs... Correct AC P/N???

AC43N

[ed styczynski]

Re: 396 Spark Plugs... Correct AC P/N???

Mine has AC43N also.

[Clem Z.]

Re: 396 Spark Plugs... Correct AC P/N???

those plugs are too cold for everyday driving and the R-45 XLS with the extended tip will run much longer without breaking down

[Mark #28455]

XLS was original for alum heads

Agree that the 45 heat range will work better than the 43 on the street, don't know if the 45N is still available.
Mark

[Joe L.]

Re: XLS was original for alum heads

Mark------

The 43XL (1967-68) and R43XL (1969) were the original plugs for aluminum head big blocks, not the XLS series. The R-43XL is still available from AC Delco.

43N, R43N, 45N, and R45N are no longer available from GM or Delco. They are replaced by the XL and XLS series.

[Clem Z.]

"S" is extended tip and the "fuel wash" cools

the tip so it acts like a 44 even if it is a 45. the secret to cleaning off the plugs in a BBC engine is to take it up to max RPM at just part throttle as this will clean the plugs without heating them them up enought to "bake" on the deposits. after that you can jump on it WOT

[Joe L.]

Re: "S" is extended tip and the "fuel wash" cools

clem-----

Yup; in fact, I'll be using the Champion-equivalent of the R-45XLS, the Champion RN14YC, in my "ZL-1".

Also, the old AC "N"-suffix plugs are very similar in configuration to the "XL" suffix. So, if someone really wants to use an "N" configuration plug (or, needs to because of "interference" problems associated with extended reach plugs), they can use the "XL" suffix.

[Mark #28455]

sorry, what I meant was

the XL plug has full length threads as used in aluminum heads, the N plug is only threaded half way as used on cast iron heads. Since he was on the NCRS web site and asking for the "correct" plug for his engine, I was merely stating the XL or XLS type was "correct" for aluminum heads, not iron heads.

Sorry for the confusion! I do agree that the 43 plug is too cool a heat range for most street use.

Mark

[Clem Z.]

XL or XLS can be installed in either BBC

cast iron or aluminum heads BUT "N" plugs can NOT and must NOT be installed in BBC aluminum heads.