[DeTomaso] Spark plug question

[Asa Jay Laughton]

The difference would be the aluminum heads.  Stock cast iron 351C heads
use a taper seat plug, like the AR-25.  But aluminum heads most likely
have a flat seat and use a sealing washer on the plug.  This helps
prevent galling that would occur if using a taper seat.  You CAN'T use a
taper seat with a head built for a washer.  So sorry, you can't use the
AR-25.

I use cast iron heads so I can't help recommend a better plug than what
you are using, except that I really like NGK.

Asa  Jay

Asa Jay Laughton, MSgt, USAFR, Retired
& Shelley Marie
Spokane, WA
******************************     
http://www.racingagainstautism.com
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On 4/6/2014 5:41 PM, Will Kooiman wrote:
> 3926 are what I use in aluminum A3 heads.  So, he's already using 3/4 reach, no gasket, narrow plugs.
>
> That's a good street plug.
>
> Sent from my iPhone
>
>> On Apr 6, 2014, at 5:47 PM, Mike Drew <MikeLDrew at aol.com> wrote:
>>
>> Brent,
>>
>> Do you have iron 351C heads or aluminum heads?  That can maybe make a difference???
>>
>> Mike
>>
>> Sent from my iPhone
>>
>>> On Apr 6, 2014, at 14:39, Brent Stewart <bjbstewart at yahoo.com> wrote:
>>>
>>> All, 
>>> The auto lite 3926 is what I have in my 351 cleveland stroker. I thought I had read that some of you had changed to the AR-25 racing on the left. 
>>>
>>> Seems to be a pretty big difference, am I doing it wrong? :-)
>>>
>>> Specifically, thread count and lack of washer have me concerned that this ain't the right answer.  
>>>
>>> Any help would be appreciated!!
>