426 Hemi Spark Plugs

[jobenz]

Morning Boys, Just purchased a 64 savoy, 426 hemi (Now a 489) Spark plugs are Champion RN9YC and gap is .042 on most of the plugs. Just a street car and was wondering if plugs are ok or should I be using a different number ??? Also is gap a little too wide ????
Joe

 

[jobenz]

Morning Boys, Just purchased a 64 savoy, 426 hemi (Now a 489) Spark plugs are Champion RN9YC and gap is .042 on most of the plugs. Just a street car and was wondering if plugs are ok or should I be using a different number ??? Also is gap a little too wide ????
Joe

Forgot to mention 11 to 1 compression, Stage 5 Aluminum Heads. MSD Ignition and plugs were black.

 

[Lefty71]

I would never even consider jumping to something else just because Joe Schmoe on the internet says!! What do the plugs looks like?? What ignition system does the car use??

 

[JDJG]

Hi Joe
Id do a general tuneup , check initial timing and total advance . Hows the carb setup on your new machine?

Good luck with it

JD

 

[6PKRTSE]

I have run RN9, RN10 and RN12'S in my 528" Hemi on the street. Didn't seem matter with my MSD 7720 Power Grid and MSD 7730 wired in. Plugs always look good.

 

[RemCharger]

I would back the gap down to .035.
Only thing too big of a gap does is find and make leaks in your plug wires.

 

[topside]

I ran RN12s in mine: only 438", but biggish Crower cam, ported iron heads, 10.8:1, headers.
MSD 6 box, Moroso wires, F150 coil.
We did have to sort the carbs (originals on original intake) with some stagger jetting and different metering rod springs, as that cam didn't make much vacuum.
After that, it was crisp & pretty dang stout, especially above 3000 RPM.

 

[Dragon Slayer]

9s sound too cold for a street car even with 11 to 1.

 

[Geoff 2]

This^^^^. Use Champion 12s or NGK 5s.

 

[Bird 426]

And, what kind of fuel was used? If it doesn't have some alcohol in it, they will turn black, at least mine did. Jetting did not matter.

 

[jobenz]

And, what kind of fuel was used? If it doesn't have some alcohol in it, they will turn black, at least mine did. Jetting did not matter.

Shell 93 Octane