I just pulled the plugs out of my '53 Chrysler 331. They are Champion J-8's. It looks like these are obsolete, but I did find some J-8C's on a tractor website. Not sure what the "C" means. What are you guys using on your iron head Hemi's? I'm also going to hook up an MSD 6AL box.
Don't worry about the C. It was added for some reason I forget. But the plug remains the same. As I remember a J plug has a 3/8 inch long thread. It seems to me that also as I remember my Chrysler had 3/4 long spark plug holes. But I never used the early 331 type heads. 53 Chryslers came with Autolite 4GS-150 plugs. AG plugs that I am familiar with are 3/4 inch reach plugs. Something like an N4 in Champion. I would check into what plugs fit your heads and get the correct reach. I have noticed lots of people have no idea what is right for their engine and will use anything that has the correct thread. After WoS is over call Rick gold at ERC. (1-800-445-1479)He will give you he correct word and sell you the correct plugs and throw in a little booklet with replacement charts.
The Champion Catalogue lists a RJ18YC, Stock Number 58 as the correct spark plug for all 1951-53 V8 Engines.
Not sure if this is correct but I have Autolite 65 plugs in my 54 331 Ind engine. They have the 3/4 thread length. I can't seem to find anything on the correct plug applications on-line for the 54's?
Correct, no washers. The conical shape of the plug creates the seal with the tube. And I'm told the washer can also gouge the aluminum tube.
Actually, it won't... The oil collects in the annular space outside of the tube and as soon as you loosen a plug the collected oil drains into the cylinder. There are tube seal 'adapter-gizmos' but the problem we have found is that the head, at the top of the plug well, is rough cast and the nominal ID can vary quite a bit so some seals fit in some holes and not in others. If you have the heads off you could, very gently, machine the top ¾" or so all of the holes to a common size that the seal kit will like then use epoxy to fix them in place. .
I have read before in other places that plug washers are not used on the early hemis.... So I guess John Gilbert was mistaken when he thought the Chadly Coupe 331 hemi should have washers on the spark plugs (Street Rodder, May 2013, page 86). But he put them in........... Can't believe everything you reads in the mags, huh?
The so-called "wide heat range" plugs. That marked the end of me using Champions. About 20 yrs ago now. I remember a buddy of mine ran around and bought up every J-10Y he could get his hands on, still has a whack of 'em. I just switched over to NGK when they pulled that BS.
The OEM plug for my 1957 Chrysler 392 is Autolite. The original number was discontinued, but crossed over to a new Autolite number 66. They work perfectly. I've been running them for 87,000 miles, and I'm only on my 3rd set.
BTTT with the same question. Also, what's your gap? Stock gap was 0.035". My 354 engine builder (Black Mountain Hemi) installed Champion RN14YC plugs with 0.035" gap and an MSD distributor. Might a bigger gap be better? TIA.
0.035 is correct. 3/4” Long thread plugs I left the washers on…. is that going to be a problem? I would rather not smoosh (word borrowed from our youngest son) the aluminum out or cause the end to split or crack
The Jalopy Journal
