Spark Plug Recommendation

[nivvy]

Never ran aluminum heads before..what plugs should I run..my final compression will be 10.9 to 1 ...

[moper]

Take your favorite brand and have Champion RC9YC converted to theirs. (or run Champions). I like NGKs, I think they are BPR6ES-11s or something like that. It's at home...lol. Heat ranges are different for everyone. Champions get colder as the numbers drop. NGK gets colder as the numbers rise. In any case, you need the longer threads, and the 5/8 hex on most aluminum angle plug heads.

[matt63]

I went through this process last year.  I'm trying NGK R5671A-7's (stock# 4091) in my Eddy heads.  They seem ok so far.  I think these are heat range 7 which is similar to the NGK BPR6's (which are very similar to my Saab's plugs coincidentally).  Champion RC9YC are cold plugs - not sure if this would be correct for you.  I think that the Champion 12 was the original spec on Mopars.  10's are another step colder.  Accel also makes a couple of plugs for the Eddy heads.  Yes, Jap plugs have heat ranges that run reverse to Champions, etc.  You can really only compare heat ranges within the brand and not from mfg to mfg.

[Grec]

Sorry to hijack your thread... but... :-)

Do NGKs run well on Mopar BBs?

I've used them religiously on japanese cars in the past so I'm assuming that they do.

Does anyone know the code for 440 plugs that would be one step hotter than stock?

I'm running 915 heads on a 440 with a six-pack, by-the-way.

I'm thinking one heat range above stock should be good.

[nivvy]

I was running NGK's on the iron heads and the car ran better with aotolite 305's....

[moper]

Do you think the plug knows what it's in? I run Autolites in my street stuff. They last well, and are cheap. I've always had issues with stronger ignitions going thru Champions. So I dont run them much any more. In my case, NGK has a V groove design that I like, and whatever the ceramic is is easier for me to read than Autolites. In the case of the heat range 9, 340s were spec'd stock with them thru 1970. And typically, you want a cooler plug than stock for most applications. So the plugs I installed were 2 ranges cooler than a stock RB (runs 12s). But I have aluminum heads with a tight chquench and chamber, and 2-3 pts of compression more...lol.

[cudabob496]

I use NGK FR5's on my 496 with aluminum heads and 10:5 to 1 compression. I also gap them at .060 and shave back the negative electrode to expose more if the flame kernal.