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Old 08-07-2013, 06:38 PM
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lal Naja lal Naja is offline
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Join Date: Oct 2003
Location: Golden Isles, GA
Cobra Make, Engine: Butler Cobra. 350 Chevy Engine, blueprinted, heads cc'd, ported, polished, manifolds matched, big valves, 1.6 roller rockers, TB Injected, mild cam, MSD crank trigger electronic ignition. TKO-600 transmission. XKE Jaguar rear. IFS by Fast Cars
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Default Butler Cobra. Spark plug boots melting

I've just got my Cobra running and have been driving it for three weeks and I'm sorting out any problems before I dismantle the car and do the body work and paint. Car is FANTASTIC and I'm LOVING it.

But I do have a problem with the number 2 and number 7 spark plug rubber boots melting as these are too close to the headers. Headers are original butler.

I have a 350 Chevy Small block with 202-160 iron heads, 62/64cc combustion chambers, straight plugs. These similar to Z28 and Corvette of the 1970-tees era. Camel Hump I believe.

I'm using Champion RJ12YC spark plugs that are one of the suggested plugs for this engine and thought I had a great solution with trying to switch to the NKG 2057 BPM8Y plugs which are 3/4" shorter than the Champion. Only problem is when these are finger tightened into the head, the hex of the plug ends up below the recess of the counter bore of the plug hole and there is no room for a socket wrench to fit to tighten it. So back to square one.

Has anyone had this problem. And how did you solve it.

Does anyone know if shorty 5/8" hex spark plug is available in a crush washer style that will fit this head. Also what is the design criteria that dictates when a tapered seat plug can be used. My heads have a nice 45 degree chamfer around the tapped spark plug hole that looks like a perfect mating surface for a tapered plug seat. The plug thread is 14mm X .375" (3/8") thread length.

BTW. Headers are wrapped with header wrap and the insulation is touching the spark plug boots on number 2 and number 7 plugs.

PS. The car LOVES the engine, so please don't hurt my feelings with wise cracks on my non traditional engine. It just a Hot Rod after all.

Thanks, Arthur

If you'd like to see my build photos click on the link. I hope you enjoy it. https://www.facebook.com/media/set/?...1&l=0d9c5c8c6d

Last edited by lal Naja; 08-08-2013 at 04:20 PM.. Reason: Adding link to photo show, typo, more info.
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