72 Brave Dodge 318 Sparkplugs

[Frank M]

Anybody know what sparkplug is called for in a 1972 Dodge 318. I have been replacing them by crossreference the plugs that were in it when I got it. It had Champion RF10C in it that crossed to an Autolite 124. These plugs have very short thread depth (about 10 mm) and a thread width of 18mm. I have not found either of these two numbers in any application guide. They usually come back with a Champion RN14YC. But the threads width is only 14 mm and 19 mm depth. I put in 1972 Dodge MB300 so there must be different heads on this motor. I'll replace them with the Autolite 124 or the Champion RF10C as I know they fit but was curious to see if anyone else uses these plugs. Thanks

[DaveVA78Chieftain]

The Dodge MH Service manual (Group 8, Electrical Section, Ignition Specifications at rear of section) lists Champion F-10 for the 318 which are no longer made by Champion (Non-resistor plug).  The Champion web site says to use Champion plug RF10C (resistor plug [inhibits radio interference]) as a replacement (http://www.championsparkplugs.com/results_cross.asp?pid=f10&x=52&y=16&seenCrossWarning=1).

Champion: RF10C
Autolite: 124
AC Delco: R83T
NGK: AR6FS-11

The 318-3 Industrial motor used in the motorhome uses the larger 18MM plug (RF10C).  The head has an additional cooling jacket around the plugs and uses a different head gasket from the 318-1 car motor.

The 318-1 car motor used the smaller 14mm plug (RN14YC) you normally see in the parts listings. 

Dave

[Frank M]

Dave,
Thank you very much for the information. I am much more confident that I am using the correct plugs. As I stated I was just using the same numbers as the previous owner had used but never could find any information as to what the engine called for. Thanks again!

[Thomas Budzowski]

I went out and checked the plugs that were in my 318-3 and they are Autolite 124.  I have since replace it with a 360 Dodge.

[polarman]

My 73 318 has autolite 45 plugs in it. I went through a bit of a run around with the parts store trying to get the right plugs, so I ended up keeping the autolite 45 plugs in it because they looked to be in fine shape.
The manual says to use Y114N plugs( or was it N114Y, I'm going by memory here), but did not specify a make.My local NAPA had no clue what that number meant.
Correction:

I had it wrote down here at work, N114Y is the recommended spark plug # for the 1973 318-3.

[DaveVA78Chieftain]

Either a 45 or a 124 will work.  Dodge manual says original was F10 and autolite crosses that to a 124.

Dave