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 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???? :shruggy:
Just run an NGK "XR5" plug and gap it at .035.....your motor will luv it ! :yesnod:
Ron
Now I saw it LOL!
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.
Quote from: ODZKing on June 19, 2017, 09:36:45 AM
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.
Depends on the cam, compression and heads. Odds are you will end up with the xr5
Quote from: c00nhunterjoe on June 19, 2017, 06:11:28 PM
Depends on the cam, compression and heads. Odds are you will end up with the xr5
All stock with A LOT of miles on the old girl. ::)
The XR5's are a great all around plug for iron head builds that run between 8.5-10.0 compression. More compression requires a colder plug while less compression needs a warmer plug.
ODZ ; I'd run the XR5's in both of those cars
Ron
Thanks folks. I ordered 16 NGKs from Rock Auto. Great price I thought, $1.39 each and same shipping 8 or 16 so I ordered 2 sets. Came to $28 to me. Cheaper that could get them locally. :2thumbs:
Quote from: firefighter3931 on June 19, 2017, 07:07:45 AM
Just run an NGK "XR5" plug and gap it at .035.....your motor will luv it ! :yesnod:
Ron
Great Spark plug. :cheers:
Too bad it's made in Japan. :brickwall:
You will be happy with the NGK's!! Like Ron said the XR5's are all around good plugs for any cast iron big block with less than 10 to 1 compression. I ran the #6 heat range NGK's in my 493 before I swapped to the stealth heads and they ran great. I am running the longer reach #6 NGK's in the stealth heads and they seem to be the perfect selection. Ron recommended the NGK's to me when I went to the firecore dizzy and wire set and they worked out great. I was always a champion guy until I tried the NGK's.......