Which spark plug best for a stock 440 Magnum?

[slsc98]

I did a search before posting but, closest thread was from 2009 and regarding a 340 so, here goes:

What spark plug size is the best for a stock 440 Magnum, all street, no racing, occasional goosing?

RN12YC or RN14YC?

I'm replacing the spark plug wires, distributor cap and rotor in my 440 (engine came out of a '70 GTX, no headers, Holley 850 double pumper) and spark plugs.


(Back now; sorry, had to chase the dog around the house for awhile, it's a nightly routine thing with him 

Anyhoo, all this was brought about by the fact that I procrastinated "cleaning up " all the excess length of the wires "spaghetti'ed" about my engine compartment so, it was only a matter of time I caught one on something (nothing more horrible than the sound of a 440 running on 6 cylinders. Ugh). That and I am suspecting the crack in my drivers side exhaust manifold gasket may have "fried" one or more of my LH boots or wires . . .

I am hoping and praying I don't have any more serious problems due to any arcing or cross firing but, since everything is unknown old to me (and it appears the rubber boots on the ends of the wires may aged, kinda drying out, losing their flexibility, I've decided to just go ahead and do the plugs,wires, Dist cap and rotor.

Sidenote: One thing I found VERY disturbing is that, with the current wire set (yellow Accel, I believe), at least 2 of the dist end boots just popped right off their terminals without even having to "pull" ort tug one them, at all.  Anyone else ever experience this?

Here's what I am considering going with and, if anyone has any better suggestions, please chime in:

I was planning on going with the unassembled, "you custom cut your desired length" wire set from Summit http://www.summitracing.com/parts/sum-g819/overview/make/Plymouth and figure I'll order a set of 3 or 4 90-degree boots since the set comes with only 5 90-degree and 3 straight boots (?)

For the Dist cap and rotor, I figured I'd go with the ACCEL Dist Cap + Rotor KIT (***Heavy Duty***): http://www.summitracing.com/parts/acc-8321/overview/year/1970/make/plymouth/model/gtx

That kit comes with a black cap, as opposed to tan but, this car is a street toy, not a show car or anything . . .

My wife is kind of turned off by the whole "blue wires inside a dark green car" thing so, if I can find orange or yellow wire custom cut sets, I'd be willing to go with those.

Anyway,before I invested anymore time into searching Jegs or anywhere else, I figured I'd solicit some feedback here as the wealth of knowledge and experience here is unparalleled!

Thanks in advance!

UPDATE: (as Johnny Cash would say, "Sunday morning, comin' down . . ."):  Now, looking hard at the:

1) Firecore 50 8.5mm Universal Fit https://www.customwiresets.com/home.php?cat=250 (Thanks, Niel; d*mn, you gotta love the knowledge on these boards!)

2) (also off the Firecore website): MSD Mopar Replacement Cap -Black SKU: DC-7431 MSD Mopar Replacement Distributor Cap,Rotor and holdown. Black https://www.customwiresets.com/home.php?cat=263 (Go to very bottom of page . . .)

3) Year One Part Number:UQ670 Reproduction LH ignition wire separator bracket for 1966-1970 B-body models with Hemi, including Charger. Used on all round air cleaner equipped cars including 1970 Charger. Bolts to front throttle return spring bracket bolt and faces forward. (Just wondering, is this really the bracket I need? I am willing to ream it out to fit 8.5mm, if need be . . .) https://www.yearone.com/Product/1966-74-a-b-e-body/uq670

and, last but not least (because I figure an ounce of prevention may be worth a pound of cure . . .

4) Year One Part Number:TT14350 Thermo Tec 4-piece Thermo-Flex S/S plug wire heat shield. This heat shield from Thermo-Tech protects the spark plug wires and boots from extreme heat. Sold in 2- and 4-piece sets. https://www.yearone.com/Product/1966-74-a-b-e-body/tt14350
Thoughts?   Suggestions?   Anyone?

[Chryco Psycho]

Doing plug tests a few years ago I found the Champions to work as well as anything & literally the more $ spent the more power lost so I use RJ12YC in a 440 , Firecore are good wires  , insulators near the manifolds or headers are good insurance . The low cost wires sets can pull the wire out of the crimped ends very easily

[slsc98]

Thanks friend, I saw where you mentioned both items in earlier, different threads; not very often I get 'excited' about wires but, well, one of life's true pleasures is a smooooooooooth idling E-body!!!!

Interestingly, there was a TV show awhiles back that tested all the alkaline batteries (e.g., D cell, C. Cell, AA, 9 volt, etc.), and they determined the cheaper the battery, the longer the life!  Go figger!

[Chryco Psycho]

 

[blown motor]

I got Taylor wires from Summit. # TAY-78351 You can order them in different colours and cut them to fit. They are available with different boot angles so make sure you order the right ones and also get the crimping tool to do a proper job of crimping the ends on. The cheap tool is all you need.

[DocMel]

Whatever boots/wires you use, take the 1 sec it takes to put on some spark lug boot grease.  It will pay off big, especially when you get some hours on your new boots   Small tube costs like $2.00

[Chryco Psycho]

put an OHM meter on a Taylor wire , give it a pull or tug end to end & measure the ohms again , they are low end quality