Spark plugs for the aluminum head?

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Mustang_Geezer
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Spark plugs for the aluminum head?

Post #1 by Mustang_Geezer » Fri Aug 20, 2010 9:59 pm

Anyone tried to experiement with differant spark plugs? Mike suggested AR 3934 Autolite racing plugs which I have run for the past 3 years. However they tend to foul out after awhile which I thought was caused by my carb.

However I took some of them to work and we matched them up to some other Autolite plugs.I'm running Autolite 3924 plugs in it right now and if they work I can upgrade to platinum or double platinum plugs using this same part number.

Right off the bat I've noticed better starting, no miss fires on a cold engine and the plugs havent had as much of a tendency to foul out.

The plan is to run them for 200-300 miles, pull them out and see what they look like. :)

Later,

Doug
1966 Mustang Coupe
206 ci Inline 6
Best ET 60' 1.84 1/8 mile 8.74 @ 79.09 mph 1/4 mile 13.67 @ 98.18 mph US 131 Motorsports Park. 4/6/13
2003 F-150 FX-4 Tow vehicle.

Does10s
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Re: Spark plugs for the aluminum head?

Post #2 by Does10s » Mon Aug 23, 2010 10:22 am

Doug,
The AR style plug comes standard with .025" gap. And that's the gap that they are suppose to be used at. They are designed for high cyl. pressures (boost, n2o etc.)
So that would probably explain the fouling.

We run AR3932 Kelly's car. 2 steps colder. But we're running a turbo and we're trying to pull some heat out of the chamber and keep the plug cool.

The standard 3934 plug is the same as the AR3934 except it has the longer gnd. strap and a larger gap.
Later,
Will
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'86 Mustang, Turbocharged, Best ET: 10.70@132.
'69 Mustang Sportsroof, 351w, auto
'63 Falcon, Turbocharged 250, C4, 9", Best ET: 10.64@127mph 11/21/14

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Re: Spark plugs for the aluminum head?

Post #3 by Mustang_Geezer » Wed Aug 25, 2010 8:47 pm

Thanks Will for the info!

I pulled the plugs out and they look fine so I'm going to keep running them until I install my new motor.

Later,

Doug
1966 Mustang Coupe
206 ci Inline 6
Best ET 60' 1.84 1/8 mile 8.74 @ 79.09 mph 1/4 mile 13.67 @ 98.18 mph US 131 Motorsports Park. 4/6/13
2003 F-150 FX-4 Tow vehicle.

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Re: Spark plugs for the aluminum head?

Post #4 by Gene Fiore » Thu Aug 26, 2010 3:04 pm

New motor? Details?? :wink:
1971 Maverick, 250I6, crank knife-edged, Clay Smith 278 solid cam, .040 over 255 V8 pistons, 10.5 to 1, Custom 500 Holley 2V direct mount, 1.6 rockers, mild port/polish, Hooker header, DUI dizzy, C-4 w/2800 stall, 8" 3.55 det locker

Best ET 1/4 mile: 14.92 at 89.61 mph on 1/12/2013

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Re: Spark plugs for the aluminum head?

Post #5 by Mustang_Geezer » Thu Aug 26, 2010 9:41 pm

Gene Fiore wrote:New motor? Details?? :wink:


Gene,

More compression, more rpm's, bigger cam than the current motor.... :wink: :mrgreen: Plus its a 66 motor so it'll have forged rods.

Its bored .030 over, 0 decked, balanced, flat top pistons, schneider race cam, arp throughout. Aluminum head, holley 4 bbl and all the other classic inline goodies will get swapped from my old motor to my new one. Then the current motor is going to be punched .080 over so I'll have a backup motor.

Machine work is finished and all the new parts are boxed up in my shop. I'll post a couple of pics when I unbag it and start assembling it.

Later,

Doug
1966 Mustang Coupe
206 ci Inline 6
Best ET 60' 1.84 1/8 mile 8.74 @ 79.09 mph 1/4 mile 13.67 @ 98.18 mph US 131 Motorsports Park. 4/6/13
2003 F-150 FX-4 Tow vehicle.

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Re: Spark plugs for the aluminum head?

Post #6 by Gene Fiore » Fri Aug 27, 2010 10:08 am

Sounds great...what are the specs on the camshaft?
1971 Maverick, 250I6, crank knife-edged, Clay Smith 278 solid cam, .040 over 255 V8 pistons, 10.5 to 1, Custom 500 Holley 2V direct mount, 1.6 rockers, mild port/polish, Hooker header, DUI dizzy, C-4 w/2800 stall, 8" 3.55 det locker

Best ET 1/4 mile: 14.92 at 89.61 mph on 1/12/2013

My Classic Inlines Photo Page

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Re: Spark plugs for the aluminum head?

Post #7 by Mustang_Geezer » Fri Aug 27, 2010 11:25 pm

Gene,

.512 lift, 280 duration, 107 lobe center.

At .050 lift is .310 & duration is 222

Compression is supposed to be right at 11.0 to 1

He did a nice job with the machine work and it is a virgin block. He had to deck it .047 to reach 0 deck and it still had the original FOMOCO stamp main & rod bearings in it.

Hows your engine coming along? Havent been on here for awhile...too many things to do... :wink:

Later,

Doug
1966 Mustang Coupe
206 ci Inline 6
Best ET 60' 1.84 1/8 mile 8.74 @ 79.09 mph 1/4 mile 13.67 @ 98.18 mph US 131 Motorsports Park. 4/6/13
2003 F-150 FX-4 Tow vehicle.

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Re: Spark plugs for the aluminum head?

Post #8 by Gene Fiore » Sat Aug 28, 2010 12:59 am

Sounds great...my engine has been done and installed back in March. Runs great but still running the 350 Holley...I still have plans to install the 500 Holley I got from you. Like you, been very busy and right now it's just too darn hot to work out in the garage when it's 112 deg with humidity. My sig has been updated with all the new stuff. :wink:
1971 Maverick, 250I6, crank knife-edged, Clay Smith 278 solid cam, .040 over 255 V8 pistons, 10.5 to 1, Custom 500 Holley 2V direct mount, 1.6 rockers, mild port/polish, Hooker header, DUI dizzy, C-4 w/2800 stall, 8" 3.55 det locker

Best ET 1/4 mile: 14.92 at 89.61 mph on 1/12/2013

My Classic Inlines Photo Page

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Mustang_Geezer
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Re: Spark plugs for the aluminum head?

Post #9 by Mustang_Geezer » Sat Jan 15, 2011 5:51 pm

After putting over 1000 miles on the plugs they still look great so I'm switching to the platinum plugs next weekend and am switching to Mobil 1 15 w 50 synthetic oil in my old engine.

Autolite plug number 3924 for regular, AP 3924 for Platinum plugs & APP 3924 for Double Platinum plugs.

Later,

Doug
1966 Mustang Coupe
206 ci Inline 6
Best ET 60' 1.84 1/8 mile 8.74 @ 79.09 mph 1/4 mile 13.67 @ 98.18 mph US 131 Motorsports Park. 4/6/13
2003 F-150 FX-4 Tow vehicle.

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Re: Spark plugs for the aluminum head?

Post #10 by AzCoupe » Sat Jul 02, 2011 11:04 pm

I had a couple questions I needed answered, so I called Autolite and talked to their in-house spark plug expert for nearly an hour. I was surprised that he took that much time to talk with me, but he was very helpful. At any rate, here's the plugs he recommended for an average performance build with 200 RWHP. Ha said to start in the middle of the range (like a AP3924) and go from there. And that for each additional 100 HP, we'll probably need to run a plug that is one step colder. In otherwords, if you have 300 RWHP you should start with a AP3923 instead.

When you check the plugs, the tip should be a hazy brown. If they are white, you need to run a cooler plug and/or richen the mixture. If they are dark brown or black, you need to run a hotter plug and/or lean the mixture. Dark black means the plug is too cold, dark brown means the mixture is rich, blackish brown means cold and rich. For more informatio on plug readings, click here.


Naturally Aspirated - Street:
AP3922 to AP3926 (Platinum Resistor - extended tip)
APP3923 to APP3926 (Double Platinum Resistor - extended tip)
XP3923 or XP3924 (Xtreme Double Platinum Resistor - extended tip)
Naturally Aspirated - Strip:
AR3910 or AR3911 (Non-Resistor - extended tip)
Boosted - Street/Strip:
AR3932 to AR3936 (Non-Resistor - standard tip)

PHOTOS: AP3924 - XP3924 - AR3911 - AR3934 (note the differences in the tips)
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Mike

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Re: Spark plugs for the aluminum head?

Post #11 by Mustang_Geezer » Mon Jul 04, 2011 8:41 pm

Mike,

Thanks for checking into that and sharing! :nod:

Later,
1966 Mustang Coupe
206 ci Inline 6
Best ET 60' 1.84 1/8 mile 8.74 @ 79.09 mph 1/4 mile 13.67 @ 98.18 mph US 131 Motorsports Park. 4/6/13
2003 F-150 FX-4 Tow vehicle.

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Re: Spark plugs for the aluminum head?

Post #12 by 65-coupe » Wed Jan 16, 2013 12:21 pm

Anybody try the E3 spark plugs?
1965 Mustang coupe, Poppy red with black interior, I6, DUI, CI alum head ported, 264/264 110 Clay Smith cam, 1.65 roller rockers, Autolite 2100 300CFM, Lokar pedals and throttle calbe, Spectre air intake. Shelby mod to front suspension, CI headers stainless with Jet-Hot ceramic coating, CI Stainless 2" impostor dual exhaust, 17x8 Coys C-67 wheels,

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