Supercharger Spark Plugs

[68Sprite]

We are running an aluminum head on Pops Bugeye and it has 14mm spark plug holes. The plugs that come with the Moss supercharger kit are for the original head. Anybody know what plug we should be using?

 

[Trevor Jessie]

Email Robert and ask him what to use: rgoldman@mossmotors.com

 

[racingenglishcars]

The originals were 14mm threads. The only possible difference is in the length of the threads. Basically short or long. Original was long. I wouldn't expect any different with the aluminium head.

 

[Roger]

The originals were 14mm threads. The only possible difference is in the length of the threads. Basically short or long. Original was long. I wouldn't expect any different with the aluminium head.

I would suggest that the "hardness" or temperature rating of the plug is another possible and even more important difference than the length. Too soft a plug can put a hole in a piston pretty quickly.

 

[racingenglishcars]

Therefore I would go with the ones supplied by Moss.

 

[JerryB]

""""" Anybody know what plug we should be using? """"""

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Originally Posted By: racingenglishcars
The originals were 14mm threads. The only possible difference is in the length of the threads. Basically short or long. Original was long. I wouldn't expect any different with the aluminium head.
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First you have to state what SIZE.....

14mm and what reach? 3/8" or 3/4" reach. Can you use a 13/16 hex...as there many more availiable heat ranges in the bigger hex. Being an aluminum head we might assume a gasketed plug and not a tapered seat?

Then the second part is

...what is the static compression ratio of the motor, what is max boost ,and do you have room for an extended tip plug.

Supplying this info then a starting point plug can be selected.

Only on the dyno and looking at EGT's will get you really to home plate. If you have any substantial boost you want to have a boost spark retard and a decent fuel curve.

Hopefully, plan B wont be just something that screws into the hole. <)).

 

[Trevor Jessie]

Robert owns the midget that they use in the adverts. He has had the engine in multiple configurations. He can give you a good recommendation.

 

[68Sprite]

Thanks for the info. I have emailed Robert and I'm waiting to hear back.