BEST Spark plug - 383

-
guzzimike

guzzimike

Well-Known Member
Joined
Jul 2, 2009
Messages
1,353
Reaction score
8
902 heads (ported/flowed) 9.5 -1 Comp, MSD6AL /Probillet Dist/Blaster-II coil/MSD wires.

Daily driver, running premium gas.

Currently running Champion RJ12YC..

Any suggestions for a better Spark plug..?

NGK, Autolites, other..?



Thanx.
 
believe it or not I have ahd the best luck with AC delco's I ahev about the same set up as you with the same displacement and the Delco's works the best, I had splitfirs and they didnt work so well.
 
i use the rj14yc (63) champions in my older big blocks but since yours sounds like its had a refresh i would say the 12s are good...
ive never used the acdelcos in any mopars but i know they work good in gms
i agree on the splitfire but i would like to elaborate... those are the worst plug ever imho...
doug
 
440SCOUT said:
i use the rj14yc (63) champions in my older big blocks but since yours sounds like its had a refresh i would say the 12s are good...
ive never used the acdelcos in any mopars but i know they work good in gms
i agree on the splitfire but i would like to elaborate... those are the worst plug ever imho...
doug
Click to expand...

RJ14YC are hotter than RJ12YC, right..?

My engine, which came form a '69 Road Runner, is supposed to run the RJ12YC..but I understand that with the quality of gasoline found today, it is recommended to run a "Hotter" plug.

I think that may be the RJ14YC...

Any ideas on equivalent part # for NGK's or AC Delco's..?
 
I'm running Bosch WR9FC in a well warmed over 383 that's a little on the rich side and never fouled one yet and starts everytime. P.S. If always had a hate on for Champions.

Terry
 
moper said:
Autolite 85s.
Click to expand...

I think that the Autolite 85s are the same temp range as my Present Champions RJ12YC plugs...which I want to change 8)

If I want a higher Temp range, it looks as if Autolites 86 are the ones...< at least as far as Autolites are concerned >


Does this make sense..?
 
I run NGK's in everything from my race hydro to my big blocks.

I have had too many bad experiences with champions
 
I run NGK V-power's in most everything high performance. Just had real good luck with them and their not hard to read. Also very hard to foul out.
 
fuel injected I run the iridiums
non injected I usually run the v powers.
with full msd I might be tempted to run the iridiums thought.
Heat range all depends on what you are doing with the engine.
On my 115 outboard I run a 2 range hotter then stock plug because I am starting and stopping it a lot on my newport I am running the recommended heat rang (with a full msd system) for all around driving, the aspen I am 1 heat ranger hotter though. (also full MSD)
The dart is also a stock heat range (orange box)
 
guzzimike said:
Which NGKs..?
Click to expand...

The V-power. According to the chart in Mancini's flyer the R5670-5 is for 8.5~9.5 to 1 comp. and the R5670-6 is for 9.5~10.5 to 1 comp. Yours falls right in the middle. If it were mine I'd err on the side of safety and try the R5670-5 first and watch them closely to see if their hot enough. If not then I'd go with the R5670-6
 
You must log in or register to reply here.
-

Back
Top