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Spark plug gap
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DRR Trophy
Picture of Mr498
posted
What would cause the set gap of .040 to open up to .060 in 68 runs? This is a 496 bbc bracket motor with 13 to 1 comp. on c-12, timing set at 37t, autolite AR 134 plugs. Thoughts?
 
Posts: 82 | Location: at the track, pa | Registered: October 19, 2005Reply With QuoteReport This Post
DRR S/Pro
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One plug or all 8?



.
Dave


I'm looking for a BBC blower manifold to buy



Living to serve mankind....
 
Posts: 3189 | Location: Planet Earth | Registered: February 08, 2006Reply With QuoteReport This Post
DRR S/Pro
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quote:
Originally posted by imakehp:
One plug or all 8?


The reason I ask is there's only 2 things I can think of that would OPEN the gap

One is maybe detonation......maybe

The other is the plugs were gapped @ .060" to begin with...

Not trying to sound like a smart ass but the gap opening is probably 99% harder/less likely then closing up...

I'd re-gap the plugs and keep an eye on them..



.
Dave


I'm looking for a BBC blower manifold to buy



Living to serve mankind....
 
Posts: 3189 | Location: Planet Earth | Registered: February 08, 2006Reply With QuoteReport This Post
DRR Pro
Picture of rusty
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a close inspection of the strap and electrode should answer your question


opinions are worth what you pay for them
1.036, 6.16@ 224

 
Posts: 557 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post
DRR Pro
Picture of 00 DEAD ON
posted Hide Post
I set the gap on my NGK plugs at .022


Brian Mollison

2008 American
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Posts: 938 | Location: Stafford, Virginia | Registered: October 03, 2006Reply With QuoteReport This Post
DRR Sportsman
Picture of FootbrakeJim
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I am amazed you got those Autolite AR134's to last 68 runs. Same plugs were good for no more than 40 every time I used them, sometimes a lot less.
Toss 'em in the barrel and get some NGK's, same price, they last forever, and they won't send you looking for phantom ignition or fuel problems that don't exist...
Direct replacement is NGK Racing plug # R5673-8, (Lot of parts stores carry them, but not under the actual plug # - NGK Part Number 3249 will get you a box of 4 at your local O'Reilly store, etc).


Dan "Jim" Moore
Much too young to feel this damn old!!
 
Posts: 497 | Location: Dallas, TX  | Registered: December 05, 2002Reply With QuoteReport This Post
DRR Trophy
Picture of Mr498
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Thanks for the replies fellas. Have been thinking about those NGK plugs for a while, my engine builder said the same thing as you Jim. The ground strap looked as if it was pulled open with pliers, yes all 8. I'm going to give the NGKs a shot but .022 seems kinda tight for MSD. I never heard that much negativity towards the auto lites. Thanks again.
 
Posts: 82 | Location: at the track, pa | Registered: October 19, 2005Reply With QuoteReport This Post
DRR Pro
Picture of J178RED
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I'm using the same plug as Jim and my engine builder said " pull them out of the box and bolt them in" .... LOL I still check them and they seem to come out of the box right at .030 , I'm using a MSD for fire... he is one funny guy but his stuff runs fast and consistent so I never question him .....


Beating Dead Horse


HAVE THEY CALLED US YET ? THEY HAVE!!!
 
Posts: 2185 | Location: OLD NICK OUT ON THE TRACK OR IN THE DESERT | Registered: March 09, 2010Reply With QuoteReport This Post
DRR Sportsman
Picture of FootbrakeJim
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Like J178RED says, they all seem to come out of the box right at .030 gap, which works great for me.
I forgot to note, the R5673-8 P/N 3249 is a non-projected tip. If you want to run projected core nose plugs, the series is R5674. The -8 is P/N 5657. ( -8 heat range is a great all-around choice. Heat range goes up as the dash # goes down, so if you run alky and want a bit more heat, go to a -7, or for a colder plug, -9).

This message has been edited. Last edited by: FootbrakeJim,


Dan "Jim" Moore
Much too young to feel this damn old!!
 
Posts: 497 | Location: Dallas, TX  | Registered: December 05, 2002Reply With QuoteReport This Post
DRR Sportsman
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Jim did you get that correct on NGK beat range? I am under the impression that smaller # is hotter. I keep the gap at .25/.30 no point in taxing the ignition any more than necessary.
 
Posts: 162 | Location: Going to or returning from the chipmine. | Registered: July 01, 2011Reply With QuoteReport This Post



DRR Trophy
Picture of JP Miller
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Smaller is hotter on an NGK. -7 is hotter than -8 and so on.
 
Posts: 37 | Location: Virginia | Registered: October 24, 2011Reply With QuoteReport This Post
DRR Sportsman
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Thanks, that's what I thought. I may have misread Jims post.
 
Posts: 162 | Location: Going to or returning from the chipmine. | Registered: July 01, 2011Reply With QuoteReport This Post
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