BB plug and gap questions:
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Burning Brakes
Joined: Aug 2000
Posts: 1,211
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BB plug and gap questions:
I think that for a 1969 427/390 the recommended plug is: A/C R44XLS. The gap is supposed to be .035 I believe. Has anyone with an electronic style ignition stretched the gap to improve performance? If so, what gap worked the best?
Regards, mark
Regards, mark
Le Mans Master
Joined: Mar 1999
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From: delmont pa
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Re: BB plug and gap questions: (marky mark)
if you use a wide gap plugs make sure to use larger diameter plug wire to prevent arc through because the larger the gap causes the ignition to build up more energy and arc through the wires. :chevy
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Joined: Jul 1999
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From: Huntersville NC
Re: BB plug and gap questions: (marky mark)
The 68 recommended plug is a 43, but consensus seems to be that is a touch too (is it too cold or hot??.. i forget) and 44 is better. I widened my gap out from 35 to 40 after installing the pertronix flamethrower coil. After all, with a name like "Flamethrower" I figured the spark could make it across an additional 35 ft, let alone .005" !!!! I noticed no difference and just went back to the stock gap. I figured why risk having confused sparks jumping around not sure where to go. 
MJ
MJ
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Burning Brakes
Joined: Aug 2000
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Re: BB plug and gap questions: (MNJack)
I think the 43 would be a colder plug. Also, I'm using a Mallory Unilite mechanical advance dist. Mallory (chrome) coil <not the highest energy one but better than stock>. And MSD 8.5m plug wires which I highly recommend (they look sharp, are individually numbered and have a heavy duty boot also).
I might try somewhere between 35 & 40. If it improves performance I'll post the results.
regards, mark
I might try somewhere between 35 & 40. If it improves performance I'll post the results.
regards, mark
