Spark plug recommendation

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Jun 5, 2013 | 07:40 AM

kgkern01

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Spark plug recommendation

I just finished assembling my 13.5:1 385, with EB ported stock castings and custom LE cam 24x/25x, running on E85. What spark plug and gap should I run with this setup? Thanks!

Jun 5, 2013 | 10:38 AM

BMX Dad

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I was running NGK Iridium IX Spark Plugs NGK-7164

My tuner said:

If your looking for max life span that is the best plug
If your looking for max power that is the worst plug

If your looking for normal plug life and max power use the NGK copper TR6 - 4177

Jun 5, 2013 | 11:16 AM

BOLO

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From: Mundelein,Illinois

NGK TR6(4177) gapped@ .035"-.038"

Jun 5, 2013 | 07:03 PM

Wicked94Z

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From: Spokane, Wa

Br7ef would be a good start. You don't want an extended tip plug or a hot plug with E85. I'd run the gap around .024"

Jun 5, 2013 | 07:14 PM

Wicked94Z

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From: Spokane, Wa

I ended up with an Autolite 3911 (5/8" gasket seat .750 reach) which has slightly projected tip, ("power" tip) but nothing like say a 3923 plug. It's roughly equivalent to an NGK -8 plug. It was worth some mph when I switched from the NGK -7s.

Jun 5, 2013 | 07:42 PM

Ed Wright

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Quote:

Originally Posted by Wicked94Z

Br7ef would be a good start. You don't want an extended tip plug or a hot plug with E85. I'd run the gap around .024"

Why in the world would anybody use a .024" plug gap???

Jun 6, 2013 | 02:26 AM

Wicked94Z

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From: Spokane, Wa

What plug gaps do you use with E85 Ed?

Don't see too many guys running 6-series boxes (I'm assuming the OP is running an equivalent) on alcohol... Why not start small and increase the gap if there are gains? I forgot to mention in my prior post, I closed the gap from ~.030" to .024" when changing from -7 to -8 plugs and saw a consistent 1/4 to 1/2 mph gain, and zero change dropping to .022" or .018" gaps.