Plug Advice..

[beanhead]

Hi, looking for some opinions on spark plugs to get my 440 going....it's .040 over, 10 to 1, Eddy RPM heads and intake with an 850 mech carb (no choke), 1-7/8 headers, comp 230 @ .050,.488/.491 cam, mopar electronic ignition for now, rebuilt awhile ago never started...I was going to just start with the 'ol RC12YC maybe some of you have a different idea? Thanks for any help!

 

[kiwigtx]

I recently upgraded from NGK BP5 to the Autolite ATL-86, after reading a lot of argument on this very topic. I have now recommended to another Plymouth owner locally to do the same. The difference in my car was like chalk & cheese. Much improved response off the throttle, and a crisper, easier start.
However, after reading some more on this topic last night, you also have to make sure that the entire ignition system is also up to speed - ballast resistor must match the coil, and the Ignition module rated and suited to the job in hand.
Ballast resistor actual resistance is a key value in the correct operation and heat range performance of the spark plug.....also affects the coil performance and life expectancy.

 

[rrTor-Red]

I agree with kiwigtx that the WHOLE ignition system is up to par. The type of spark plug would be the final "ingredient" to this process.

 

[Superb Bee]

its hard to say what plug if your changing your ignition, with the stock mopar e system, I think the 12 is where I would start. If you are running msd or something nice you want the plug and wires that get you the most out of the system..

 

[mopar73dge]

I think with older carb engines a spark plug up grade is a very small improvement or none at all. I had Bosch Platinum for 15 years in my 318 with a 340 cam spec. ran great no big change in performance versus Autolites I had always used. This past Summer I recently changed them to a set of NOS Champion original spec plugs these have the Mopar logo on the plug and the nut part is silver plated, these are brand new (e bay 35.00). I could not believe how much better it ran, smoother, better idle after a cold start and more power it was like a different engine Wow, I also have stock NOS Mopar plug wires, coil, ignition and resistor and Purolator stock air filter. A K&N air filter I had in there many years was a mistake, not a great idea, the stock filter for this type of engine was the better choice for me. Many times we do things and it seems its better, but it is all in our heads this time it was noticeable (plugs). I believe stock is the way to go everything must match one upgrade in a plug will make very little difference, so I keep this car stock and I wish I did that 15 years ago. NGK, Bosh all those fancy electrode plugs did nothing.

 

[beanhead]

I recently upgraded from NGK BP5 to the Autolite ATL-86, after reading a lot of argument on this very topic. I have now recommended to another Plymouth owner locally to do the same. The difference in my car was like chalk & cheese. Much improved response off the throttle, and a crisper, easier start.
However, after reading some more on this topic last night, you also have to make sure that the entire ignition system is also up to speed - ballast resistor must match the coil, and the Ignition module rated and suited to the job in hand.
Ballast resistor actual resistance is a key value in the correct operation and heat range performance of the spark plug.....also affects the coil performance and life expectancy.

Ok makes sense...at the moment I'm using the orange ECU, the ballast resistor that came with the kit and a regular accel superstock coil....(not the big square one)

 

[RestifiedBee]

E3 52s w/a MSD 6al & MSD billet distributor.

 

[lewtot184]

find some cheapo autolite 3924's and happy motoring.