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Spark Plug Help

ODZKing

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I posted over at DC.com as well and seems no one has an answer.
Back when we did the 73 engine, in checking on plugs for the 400 4bbl, I came up with the original # of J11Y. I crossed it (then) to RJ14YC. I am about to get a new set and to my surprise, what is recommended RJ12YC which is the same plugs as my 67 - 383 4bbl.
http://www.sparkplug-crossreference.com/convert/CHAMP_PN/J11Y
So researching as I do, I realized the RJ14 is a bit longer. Not being a genius when it comes to this I have to question ... what is the difference between the two lengths and have I been using the WRONG plugs in my 73 400 4bbl all this time?
 
Dc.com....rather quite over there these days:realcrazy:.....

RJ12YC(colder) this is the correct plug for your 400....the reach is .380"

RJ14YC is .375"...Difference is this one is a hotter plug...

IMHO the newer Champions are junk and if you want to run champions then pay up for an NOS set of J11's. The old plugs are a night and day difference in quality, longevity and performance....

If you want the cheaper priced new plugs the first choice is Autolite 85's or NGK's.....
 
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Weird I didn't reply there since in my Mopar Boards routine DC.com is my first board to visit. Simply I just missed.

I always have got locally J12Y because were the only ones available locally and used with success. Haynes manual says RJ12YC for 70s HiPo big blocks

When i got my Credit card and was abl to import parts from USA, got around two sets of RJ12YC, then changed to NGK per advises, XR5's which are V groove.
 
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with champion plugs the higher the number the hotter the plug. j11y's and j13y's were designed for the mopar head. the projected tip on these two plugs is a little longer than j10y's and j12y's. the j11y and j13y plugs are extinct. the j12y will work. an autolite 85 will work well too. the original plugs were non-resistor. the j12y and autolite 85 are resistor.
 
So if I go with NGK's, 400 = XR5.
How about 383 4 bbl also, which NGK for that engine?
In looking at Rock Auto, they recommend XR4's for the 383.
 
XR5's for both.....

XR's are recommended by the general search feature because 383 is a lower compression motor but it doesn't account for your needs...
 
OK, same price as Champions so I will give them a shot.
BTW, if anyone is looking, $1.38 at Rock Auto, cheapest I can find. $5.99 shipped to me for 16 (2 sets). $28 and change, is still cheaper than I can get them locally.
 
OK, same price as Champions so I will give them a shot.
BTW, if anyone is looking, $1.38 at Rock Auto, cheapest I can find. $5.99 shipped to me for 16 (2 sets). $28 and change, is still cheaper than I can get them locally.
It will be 28 bucks well spent...
 
They allways have a discount code ( 5% tipical )... is just about search it. I even have googled to find it, but lot of ppl uses to post them on the boards ;)


I have got it emailed sometimes
 
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