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What spark plug are you using in your stroked Hemi #2536207
08/14/18 03:23 PM
08/14/18 03:23 PM
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cheshire, ct
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davesmopars Offline OP
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What spark plug are you using in your stroked HemI street car pump gas
thanks

Last edited by davesmopars; 08/14/18 03:37 PM.

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Re: What spark plug are you using in your stroked Hemi [Re: davesmopars] #2536240
08/14/18 04:16 PM
08/14/18 04:16 PM
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Bend,OR USA
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I would start with either Champion RC9YC or Autolite #3911 or 3910 is(colder than 3911) or Autolite 3923 or 3924 scope
Any of them will work with iron heads and up to 11.5 to 1 compression ratio on 91 octane pump swill scope


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: What spark plug are you using in your stroked Hemi [Re: davesmopars] #2536663
08/15/18 11:25 AM
08/15/18 11:25 AM
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Marion, South Carolina [><]
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NGK 4554 (R5671A-8) in my 11:1 pump gas (93) 572" Hemi. I use these when I run it NA and on the street. I throw a colder set in it for nitrous use.


CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
Re: What spark plug are you using in your stroked Hemi [Re: davesmopars] #2536715
08/15/18 01:07 PM
08/15/18 01:07 PM
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cheshire, ct
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It's a 604 aluminum head 10.2 compression it this make a difference

I have written on paper work I think this what it says real bad writing
NGK NY9
NGK N 11 (i think)

Champion RN11Y

Then say start with 9

This was written in the notes, very messy hard to read

Last edited by davesmopars; 08/15/18 01:12 PM.

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Re: What spark plug are you using in your stroked Hemi [Re: davesmopars] #2536727
08/15/18 01:28 PM
08/15/18 01:28 PM
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Champion numbers tell you about the plugs, if you wanted to start with RN9YC,R= resistor plug, N=13/16 socket size with 3/4 inch thread length, 9= the heat range , bigger #s are hotter, smaller are colder in Champion plugs up Y= extended spark plug ground strap, C=copper core.
On your deal I would start with a cold plug like the RN9YC or the smaller 5/8 socket size RC9YC plugs scope up
IHTHs


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: What spark plug are you using in your stroked Hemi [Re: Cab_Burge] #2536786
08/15/18 03:30 PM
08/15/18 03:30 PM
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Washington
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Originally Posted By Cab_Burge
Champion numbers tell you about the plugs, if you wanted to start with RN9YC,R= resistor plug, N=13/16 socket size with 3/4 inch thread length, 9= the heat range , bigger #s are hotter, smaller are colder in Champion plugs up Y= extended spark plug ground strap, C=copper core.
On your deal I would start with a cold plug like the RN9YC or the smaller 5/8 socket size RC9YC plugs scope up
IHTHs



I agree with cab. No need to mess with the N series Champion plug. Just use the C series and that way you get the 5/8 hex instead of the big, clunky 13/16 hex.

If you think you need the 11 heat range Champion, I don't think they have that in the C series. Don't have my catalog handy but if that's what you need, you can use the RC12YC instead.

At 10.2:1 compression and pump gas my guess is you'll need the 12 but I'd start with the 9 and work with it. Easier to tune up to a warmer plug than it is to start on the warm side and have issues. IOW, I start colder and then use a warmer plug if I need it.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: What spark plug are you using in your stroked Hemi [Re: davesmopars] #2536798
08/15/18 04:07 PM
08/15/18 04:07 PM
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cheshire, ct
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And this is why I ask. thanks

Looks like Champion is the choice.
I will start with the RC9YC plugs

Last edited by davesmopars; 08/15/18 04:11 PM.

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Re: What spark plug are you using in your stroked Hemi [Re: davesmopars] #2538488
08/19/18 11:54 AM
08/19/18 11:54 AM
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cheshire, ct
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What do you recommend for a gap.


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Re: What spark plug are you using in your stroked Hemi [Re: davesmopars] #2538528
08/19/18 01:23 PM
08/19/18 01:23 PM
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Posts: 43,007
Bend,OR USA
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What ignition and coil are you using?
If a MSD race 7 box with the proper coil set them at .045, if a MSD 6 with a regular coil try .035 shruggy


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: What spark plug are you using in your stroked Hemi [Re: davesmopars] #2538905
08/20/18 10:40 AM
08/20/18 10:40 AM
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Northeast Indiana
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RC12YC in mine, gasket left on, 10:1 iron heads. Sheepishly admit that I've never gapped them.







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