I need to replace my Champion J11Y plugs on the 70 Roadrunner 383 Auto. Can't find these or J10Y but I see that the J11Y crosses with new Champion W7FC. Mechanic does not want to go with the J12Y which is a hotter plug. Wants a colder plug. Any suggestions. This is not for racing just cruising. I just need a new set of plugs that will work.

So I guess no one uses spark plugs in their mopars anymore?

Autolite 75's I believe. I use Autolite 74's or 73's in the 440 in my 63. Ron

Thanks Ron. I had heard of a suggestion of Autolite 85's also.

autolite 85, j12y is o.k. for cruising. i use bosch 4036 in both my 440's; they're a tad hotter than the j11y.

Thanks for the suggestions. My local auto store dug up 5 boxs of Champion J10Y with 8 plugs to a box. I bought all 5 boxes. 4 boxes will be appearing on ebay shortly.

Try this: http://home.att.net/~ngkaz/wsb/Master_Cross_Reference_Charts4.xls

That's pretty nice!

Thx

Interesting....I run rj12yc's in my 383 with orange/silver box and accel/msd coil in my 73 charger with no problems.
You must have a high compresion ratio? I have 150-160 psi cold cranking per cyl.

I heard the autolites where good too.....

Auto-Lite 85s, same as 75s but resistor..

Program will not open. Appears to be Excel which I don't have.

New Autolites I hear are made in China. And they have reliability issues. I was using them. I am thinkin NGK or back to Champion.