Spark plug question for my 440

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N G K

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V Power forgot the #

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Please forgive a novice question and not to hi-jack but Mancini's page is great but I see they list many plugs for the different comp ratios...

What is the difference between these plugs?
Does a "street car" not see much gain from this as I have always just used a standard auto parts store suggested replacement.
Or am I just not well informed?

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The basic difference is the heat range{length of the porcelin tip}...The over-the-counter plugs are fine for most street engines..It really comes down to a matter of preference...I've always used a champion plug {like the RJ12YCs,it's a "shorty" too} in a big block and have had good luck...Autolite,Accell,NKG all get good reviews and some swear by/hate them because of their own experiences... The general rule is start with a factory type plug for the application and see how the engine likes it...If it's burning clean and lasts thousands of miles there's no reason to change it...There's no magical plug that'll give huge gains over a clean running set-up....
Now,highly modified engines may need a plug with a different heat range depending on many factors including compression,exhaust,carb intake, etc...Plug reading is a real science and some are very good at it... In my experience a good number of guys seem to have other engine/tuning issues and want to blame it on the plug and start swapping heat ranges and/or brands labeling whatever plug brand they tried as "junk".. ....

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I ran them a few years back.Never saw any gains for the bucks.Went back to Autolites.Now with the aluminum heads I run NGKs.Rocky

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I still run Autolites. In everything.

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I have a 440 built to a 512 stroker, 906 heads, TTI 1 7/8 headers.

I am looking at getting new spark plugs. Are these any good?

Accel - Header Plug

Part # 8197 / 437s

Thanks


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I think that the 437 is probally a hot plug, what compression ratio are you making and what grade of gasoline are you using?I have used the Accel 137, 134 and 132 in a iron headed BB similar to yours (440 block 4.25 strokex4.375 bore with ported big valve 906 heads)with 9.25 to 1 compression using CA pump swill, it ran fine on the dyno but I did't get the car running until we moved to Oregon on the summer of 2005. It, the motor, seemed to like the 134 best Oregon did not have Ethanol in there gas back then. I swithed the heads that winter to a set of Eddy RPM aluminums and I had switch the plugs to longer reach plugs,Autolite AR3911 and AR 3910 I don't think Accel offers more than one shorty spark plug part number

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I have not used the #437s "header plugs" but I have been using the Accel "shorty" plugs (576s)on my 440 with Hedman headers for the past 35K miles and have not had any problems. The Summit part number is ACC-0576S.

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