tapered or gasket seat plugs in GN1 heads ?

[tttype]

Any opinions on which is better ? Tapered or gasket seat plugs in GN1 heads ?

Thinking of autolite brand for ease of finding locally.

 

[RmvBfrFlght]

I've always preferred flat gasket seat plugs in aluminum heads. The reasons are that the tapered portion in the head can gall when R&R'ing the plugs. And the aluminum can 'flow' due to the pressure on the tapered area.

I can't say whether either of these actually occurs or not, just the way I look at it from the best reliability viewpoint. Like Murphy, if it can happen, it will happen, so I don't give that Murphy guy the chance.

RemoveBeforeFlight

 

[Phoneguy]

I just went to the gasketed type myself. NGK R5671A-9 non projected tip gapped at .022

Bryan

 

[whitehot1]

I've had my GN1 heads since 2001 and the plugs that Champion recommended in the installation sheet that came with them was Autolite 103 or 104 which are tapered plugs, i've also used NGK tapered plugs with good results.

I've never left the plugs in these heads longer than 3 months without taking them out for inspection cleaning or replaceing, and never had a problem with the aluminum threads.

So not sure if a gasket type plug is better. Maybe it's just what a person may prefer to run.

 

[jpwalt1987]

I use autolite 3922 gasketed plugs.

 

[MSDGN]

I've run all different brands/temp ranges with my GN1's and my car likes Autolite 103's...

 

[trbojo]

I'm running NGK Iridium TR5IX right now..tapered seat gapped at .032 24 psi....working pretty well...always use a little anti seize when inatalling..

 

[tttype]

Called Autolite tech line & asked what is closest to 103 but with gaskets.
He said 3923 is same, so picked up a set of those. They were even in stock so they must be used in something popular. As the 103's were special order.

I forgot to ask tech guy about 103 equivilant with gaskets & non projected tip. May have tried those latter.

 

[jpwalt1987]

I run the autolite 3922.

 

[toomanymodz]

Autolite 103's here, with anti-seize of course. Gapped at .028 Just checked 'em today and they look perfect.

 

[RmvBfrFlght]

Called Autolite tech line & asked what is closest to 103 but with gaskets.
He said 3923 is same, so picked up a set of those. They were even in stock so they must be used in something popular. As the 103's were special order.

I forgot to ask tech guy about 103 equivalent with gaskets & non projected tip. May have tried those latter.

Into the racing plugs for those: AR3933

Non-projected tip, cut back ground, although they are a non-resistor plug. Not sure if that would be an issue or not. There are also plugs for one & two heat ranges colder in that style (AR3932, AR3931).

There is the 403 spark plug (and 402, one range colder). These are flat gasket seat, 3/4" reach, resistor, non-projected, with a 13/16" hex for the wrench. Should be enough room for the larger hex, but would eye-ball it first.

In that same 13/16" hex is the 4063 & 4062, these are also colder then the 403 and have a necked down center electrode. Used in some performance cars (porsche, lamborghini) and a bunch of watercraft and motorcycles.

RemoveBeforeFlight

 

[tttype]

Into the racing plugs for those: AR3933

Non-projected tip, cut back ground, although they are a non-resistor plug. Not sure if that would be an issue or not. There are also plugs for one & two heat ranges colder in that style (AR3932, AR3931).

There is the 403 spark plug (and 402, one range colder). These are flat gasket seat, 3/4" reach, resistor, non-projected, with a 13/16" hex for the wrench. Should be enough room for the larger hex, but would eye-ball it first.

In that same 13/16" hex is the 4063 & 4062, these are also colder then the 403 and have a necked down center electrode. Used in some performance cars (porsche, lamborghini) and a bunch of watercraft and motorcycles.

RemoveBeforeFlight

These sound cool, will have to check if 13/16 will work.

Whats the thinking behind non projected plugs ?
Work best after a certain boost/ HP range ?

 

[RmvBfrFlght]

A non-projected nose spark plug is less likely to over heat and cause pre-ignition during sustained high speed driving. And is more likely to foul during low speed driving then a projected nose spark plug.

Myself, I run the coldest spark plug possible. As long as it doesn't foul out, it isn't too cold. Running in closed loop prevents fouling to a large degree. Between that and a good ignition system can run very cold plugs.

RemoveBeforeFlight