Supercharger Spark Plugs

[jrvariel48]

I'm looking for some recommendations for spark plugs for a blower motor. They'll be going into Edelbrock 1116 heads. A friend mentioned the Autolite 405 or the 3924's
Any input is much appreciated!
Thanks

[solidaxle]

For spark plugs I only use NGK if your heads have the standard length flathead plug thread length then I would use NGK B-4L or B-6L plug gap at .035 Don't forget to check the valve to plug electrode clearance especially if you have a cam that lifts over .350 to be sure they don't touch. If you find the plug is to close you will have to add an additional spark plug washer to gain a bit of clearance. If the heads you have use the newer design 3/4 inch long plugs I still use NGK the number series is B-4 and the selection is greater they also have B-6, B-8 B-9 etc. On the NGK plug the higher the number the colder the plug.

[Ronnieroadster]

Joe the only plugs to use in my opinion as well what Solidaxle posted would be the NGK your Edelbrock heads will need the long reach plugs so that gives you a huge verity of heat ranges to work with. So for starters go with the B-6. One thing to remember with NGK plugs when the plug number goes down thats a hotter plug which is opposite of most plug number series by other brands. The fact your working with a street driven gas burning blower motor you will not require any special plugs. And if you decide to race the combination the NGK plugs will work perfectly then also.
Ronnieroadster

[solidaxle]

Ronnie's the one who advised me on spark plugs. I should have given him credits in my response.

[jrvariel48]

Thank you Ronnie & Solid! Ronnie's been a huge help with air/fuel and timing tips for running a blown flathead! I'm using a Kiwi L100B cam in this motor with .369 lift on the intake and .368 on exhaust. I'll have to check clearance, but I think it'll be fine. I'll post the results
Thank you, Joe

[Tim Ayers]

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May seem obvious, but besides feeling the contact, what do you put on the plug to check for contact? Blueing?

[GOSFAST]

Hi Joe, with those Edelbrocks no problem with the valve/plug clearance.

With a non-projected tip plug you have over .470" at the electrode from the head surface, this is without the head gasket thickness. Head gaskets average .050" give or take a few!

The photo below shows a non-projected .750" long reach plug (right/difficult to see) and on the left the same plug but with the projected tip, about .100" deeper into the chamber!!

The choice/brand of plugs is really a customer decision! We've been comfortable dynoing all these years with the Autolite plugs, most street builds here get those 3924's, we refer to them as "pump-gas" plugs!

Thanks, Gary in N.Y.

P.S. To be absolutely safe you could put one plug in without a gasket, if it turns over without contacting the plug you'll be OK! Also, DO NOT use those projected-tip plugs, even though I believe this type plug will clear, they will yield much less clearance.

[Ronnieroadster]

Originally Posted by jrvariel48

Thank you Ronnie & Solid! Ronnie's been a huge help with air/fuel and timing tips for running a blown flathead! I'm using a Kiwi L100B cam in this motor with .369 lift on the intake and .368 on exhaust. I'll have to check clearance, but I think it'll be fine. I'll post the results
Thank you, Joe

Joe your welcome the best plug option is the NGK any other type is a waste of your money as you know my recommendations are from experience on the road on the track and on the dyno.
Ronnieroadster

[jrvariel48]

Thanks again everyone! I'm going with the NGK B6ES (part # 7432)

B-14MM thread
6-Heat rating
E-19MM(3/4") reach
S-Standard type electrode