The Stovebolt Site Forums The Shop Area Engine Shop correct sparkplug #

I could not go back to 54' on the AC website.

Can someone tell me what is(or where to find)
the correct AC plug number for a stock 54' 1 ton?

Are there any optional plugs listed as was
the custom in the 60's ??

thanks
chnaus

Should be an R43. From what I've been told, the other heat ranges have been discontinued in that plug.

Don't bet on it! I just installed a set of R45's in a 54 Burb with a 261.

R43: cold- - - -highway driving only
R44: warmer- - - -city/road combinations
R45: hot- - - -city only, or less likely to oil foul with bad rings.
Jerry

Where did you find the other heat ranges? I was told that AC had pared it down to just the R43s for the older 6. I do have a set of R46s, but my engine just wasn't happy running them, so the R43s went back in.

O'Reilly Auto Parts in Fayetteville, TN had them. I don't think it's unusual for those numbers to be in stock around this area, at least. The ones I have trouble finding are the "C" prefix commercial plugs, such as a CR45, etc. They have a much larger center electrode, and were designed for delivery trucks, taxicabs, etc., where lots of stop & go driving was done. Commercial plugs would outlast regular ones about 3 to 1 in the dirt track race car.
Jerry

Don't know where you guys are finding those plugs, let alone the numbers, when I look in the Delco book at Farm & Fleet the only number I've been able to come up with is R45. I don't get out all that often so if you know of any online sites that have PNs' or AC Delco listings/catalogs I sure would appreciate it of you could post a link for me.
Denny Graham
Sandwich, IL

Check on EBay. There are dealers out there that have NOS stuff that they are selling. I scored two 8 packs of R44SX plugs that Tom Langdon suggested for my 261 with dual two bbls. Cheap too.

I got mine from Danville Auto Parts, my favorite flaps. Old time parts store with real car guys, not any goofball off the street. Theyv'e been having some problems with getting stuff from AC since they (AC) started cutting back on the stock #s. They've been condensing certain #s down to common fitments, like oil filters on the late model Chevy trucks. Only the short one is available from AC, gotta go aftermarket to get the long one now. I'm planning to go either Champion (J8C) or maybe NGK for the next set.

There should be a corresponding Champion or Motorcraft number, although I'm reluctant to substitute off-brand parts. Original equipment parts like AC plugs in GM vehicles just seem to work better, but if AC is going to quit servicing the parts we need, I guess we're going to have to go elsewhere!
Jerry

A while back, I bought a few sets of NOS AC R44 made in Gt. Britain, sometime in the 60s.
They still have painted rings on a saw-blade-ribbed porcelain.
Easy to distinguish from the newer AC plugs.

You can't go wrong with the shop manual's recommendations.
I used to always go with the R45S the parts stores offer for late 235/261, but I like the stock plugs better.
It felt the same when I started using straight grade oil.
Temps get pretty high after a couple of hours on CA desert freeways this time of year.

The right choice depends on your driving and climate conditions and reading the plugs.

For mostly city driving and colder winters, the hotter AC 45 plugs and multi-grade oil would be better.


It's funny though, at the end of the day, it's amazing how well these engines run, even if you don't get them ideally tuned.
Then again, she truly wakes up and just keeps on going, if you give her what she likes best.