440 spark plugs

ruffcut

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Depends on stock or aftermarket cylinder heads.
 

RemCharger

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Compression?
These are decent for a 13 to 1
20221123_151859.jpg
 

BeepBeepRR

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Also depends on the head numbers. 452 heads and 906 heads take different plugs due to the 452 heads having a bump out near the spark plug hole.
 

Black_Sheep

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Autolite 85’s, but they are getting harder to find. Following to see what other good options are out there…
 

Geoff 2

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'Race' as in 1/4 mile racing? Standard heat range, stock or aftermarket heads, NGK 5 heat range.
Race, as circle track racing at WOT, a colder plug should be used. Power adder, nitrous, blower etc also needs a colder plug.
 

lewtot184

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j11y has a better tip location in the chamber, non-resistor (which could be an MSD issue) and is reasonably cold enough for racing. unfortunately they are extinct.
 

Geoff 2

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The tip location is the same for THAT plug design. What changes with heat range is the amount of insulator area that contacts the spark plug body to transfer heat away from the centre electrode to the body..
 

Sinitro

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For Champions, my preference are the J10Ys...
I still have a couple of sets stored away..

Just my $0.02...
 

440 PHIXX

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Only the motor home heads.
I remember those DC manuals referring to Motor Home 440 blocks having the figure 8 cooling passages. I’ve seen them on every ‘75 and later 440 block so far.
 

RJRENTON

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AAAHHHH....the old NGK plugs are "best" ...controversy lives on and on an on.....ad infinitum....if a person thinks NGKs are best....great....I use what the engine likes, albeit CHAMPION, AUTOLITE, AC etc that does not make my brand selection the best....only my preference.... just my opinion of course....
BOB RENTON
 
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