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ncmountainman

spark plug indexing?????

11 posts in this topic

anyone know anything about it? supposedly,you mark open side of the plug and then use these shims(between the plug and cyl head) to change the position so that the open tip is facing the intake side of the cyl....parts unlimited sells them for like $8. says its been used in indy/form 1 racing for yrs. seems like a sound concept to me that might increase throttle response and decrease flameouts :thumbsup:

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anyone know anything about it? supposedly,you mark open side of the plug and then use these shims(between the plug and cyl head) to change the position so that the open tip is facing the intake side of the cyl....parts unlimited sells them for like $8. says its been used in indy/form 1 racing for yrs. seems like a sound concept to me that might increase throttle response and decrease flameouts :thumbsup:

It does sound interesting.

I wonder if anyone has some test results for them..

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it is a VERY old drag racing tip.

actually, you want the opening of the spark to face the exhaust. not the intake. that way the intake charge (of fuel) does not soak the electrode and cause a fuel foul or potentially blow out the spark.

some make more power this way, others do not. depends on the motor.

here is the trick, you are gonna have to look down the spark plug tunnel (after using a magic marker on it) to determine just where the tip is. then shim accordingly.

gonna take some dental mirrors and a flashlight for sure!

:thumbsup:

p.s.

a link to ngk 's site on it:

http://www.ngksparkplugs.com/techinfo/spark_plugs/installation.asp?nav=31300&country=US#indexing

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it is a VERY old drag racing tip.

actually, you want the opening of the spark to face the exhaust. not the intake. that way the intake charge (of fuel) does not soak the electrode and cause a fuel foul or potentially blow out the spark.

some make more power this way, others do not. depends on the motor.

here is the trick, you are gonna have to look down the spark plug tunnel (after using a magic marker on it) to determine just where the tip is. then shim accordingly.

gonna take some dental mirrors and a flashlight for sure!

:thumbsup:

p.s.

a link to ngk 's site on it:

http://www.ngksparkplugs.com/techinfo/spark_plugs/installation.asp?nav=31300&country=US#indexing

thanx for the reply,not to be argumentative but the link you supplied said most benefit towards the intake side but some the exhaust...the ones that came to my attention specifically state intake side. what are you basing the decision on to face them to the exhaust side with our configuration?

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Why not just use an old plug gasket to do the same thing for free? :thumbsup:

you get 4 shims(they look to be about .010"),i'm not quite sure that the plug gasket will put you where you want to be. and you sure don't want to use 2 of those :ride:

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Steve's right on the count that the trick goes back a good distance in time, and I do remember it being that you were supposed to face the "open" side toward the exhaust.

However, the the thought behind the current recommendation is to expose the spark more fully to the intake. What I have always found interesting is that none of the valves are open during the the ignition event anyway.

More likely, it could have a minimal effect on the initial spread of the flame from the point of ignition. Some years ago, Chevrolet racing found that angling the spark plugs of a small block Chevrolet engine 12 degrees toward the exhaust, which moved the inside end of the plug perhaps 1/4", resulted in 10 more horsepower in an otherwise unmodified LT-1 350.

Regardless, I doubt you'll notice anything from the effort in simply indexing the plug, but hey....

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well even if it doesn't do anything,i'd be able to say my plug is indexed :thumbsup: i like messin with stuff so i guess i'll give it a try in each direction and see,i would think that being fr to rr might just be better in either direction than having it to one side or the other?

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