E85 Spark plugs on Champion Aluminum heads

[1NASTYGN]

Current have Autolite 3926. I am being told that we have to run a colder spark plug when converting to E85. NGK at a heat range of 7 is recommended. What are you all finding? What have you seen that works?

 

[BEATAV8]

Autolite AR474, AR473, and AR472.

AR472 is the coldest. On the cold side of an NGK 9
AR473 is on the warm side of NGK 9
AR474 is an NGK 8

These are tapered seat 14mm 3/4 reach plugs, which is what a standard GN1 head calls for. non projected tip with cutback strap.

I run the AR474 on the street with E85 with good results. Keep the 473 and 472 on hand for track days. If your motor is mild with strong vacuum and can run near stoich most of the time, you could probably run the 473 or 472 on the street without turning it black.

 

[1NASTYGN]

What gap are you running on the 474?


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[larry33kc]

I think mine are 3933 for E85. I have Champ R's and they are 12mm plugs

 

[BEATAV8]

What gap are you running on the 474?


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.030

 

[1NASTYGN]

FYI
I ran the AR474 and my car was shutting off while idling and running terrible. I took them off and put my old plugs and the car runs like a beast. I still feel the plug I am running is too hot. Is there anyone running the GN1 Aluminum heads and E85?

 

[BEATAV8]

Maybe your AR474 plugs were gapped wrong or defective?


other "cold" racing plug choices for a GN1 14mm thread are:
NGK B9EFS or B8EFS
Champion S57C, S59C, S61C

http://www.jegs.com/i/NGK-Spark-Plugs/739/B9EFS/10002/-1

http://www.jegs.com/webapp/wcs/stor...erPage=90&Ne=1+2+3+13+1147708&searchTerm=S59C

 

[MNwe4]

Is anyone using the Autolite 103's or 104's? With alky injection I used to run the 104's and now on e85 I put in the 103's. Haven't had the chance to do any WOT tuning due to boost creep issues, but for idle, cruising, and quick throttle stabs they seem to be working properly. Swapping plugs on Saturday to kick off the season and am wondering if I should be using something else.

 

[TT/Ameasap]

NGK7 here. Im running stock ignition with VB and need to regap. but currently at .023

 

[ULOSE2A6]

GN1's and E85, I was running the NGK R5671A-7 gapped at 0.32 which is a hot plug, my boost was 20lbs and I had no issues, idled fine and ran clean, but I was told that the colder the plug the better so I put the NGK R5671A-9 in gapped at .028. Haven't had a chance to get on it yet, but it idles fine and drives cleanly. I figured I better put the colder plug in before turning up the boost.

Regards,
Shev

 

[SloGN]

I don't run e85. But I do run alky injection and the best plug for my application has been the AR3933...they have a short ground strap to prevent pre-ignition of alky .

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[Boost231]

The colder the better.

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[Turbo38V6]

What do you guys use to gap the AR 474? Tool wise I mean. They have a short ground electrode as opposed to an Autolite 104. The latter is very easy to do with gapping pliers.