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Discussion Starter · #1 ·
for a 347 ,alum head ,flat top piston engine is there a "preffered" plug and gap set-up? I have the pertronix "HEI" distributor and like autolite plugs but don't know which ones to get or how much gap.I have been told .045 or more is "ok" gap for this set-up but that seems high to me.
 

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When running a high energy ignition you can open up the gap a little bit but it does place more stress on the cap & wires, Try this, start out w a .035 gap open up .005 @ a time when the gap gets so big it looks like someone scribbled lenghth wise up & down the porcelin insulator with a pencil go back down .005 & call it good. if running NOS though you'll want a smaller gap
 

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IF you're spraying, turbo, blower, or alcohol.....035" gap is about right. Maybe a little less if you're boosting the crap out of it. I've tried wider gaps, no change, narrower, again no change. I just check 'em out of the box now and usually just leave them at .035".

I run Autolite 3933's...Victor Jr heads, also have 2 other sets of 3933's in different engines, both of those have RPM heads.
 

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Discussion Starter · #6 ·
what about 3923 thru 3926 autolite as i have aluminum heads and 10:1 compression in a 347 daily driver
 

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Try O'Reilly auto parts...part number is either AR3933 or 3933. It's a race plug.

If you can't find either one, you can always opt for either the 3924 autolite or the Motorcraft AGSP32C...fits '93 Taurus SHO auto I believe.
 

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Good choice.I run the 3923's with nitrous and a 32 gap. 3924's on motor. Advance auto parts can get them!


<font size=-1>[ This Message was edited by: ran347nosgt on 7/27/06 10:40am ]</font>
 

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Discussion Starter · #10 ·
i am running the pertronix "HEI" ignition ,is 32 a big enough gap with a 10:1 347 or is more better ? 3924 autolite for me then!
 
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