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Edlebrock RPm heads, Vortech - what autolite plug?

323 Views 5 Replies 4 Participants Last post by  Frank n Sons
We have been using, as per Edlebrocks suggestion, Champion RC12YC plugs in 3070 with no problems. We have now added a blower to the car and have been told by Vortech that we will need a one range colder plug. I'd like to go with Autolite. The RC12YC Champ plugs = AR3924 Autolite. The question is: Is the Champ RC9YC one step colder? It cross-refs to Autolite AR3923 which sounds right as it is one number less than stock. Anybody? Bueller? Bueller?

Frank n Sons.
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Thanks Gordon. I would have thought that with the RPM heads that that plug would be to cold for every day driving and occasionally (OK, maybe more than just occasionally) jumping on it. What do you think for a gap? I've been told by all the blown Mustang people to close the gap on the plugs to about .35 to keep the flame from getting blown out.

Phil - that is exactly what we were thinking so we got a set of 23's last night and are going to put them in today.

Wade - we have MSD6al and MSD Blaster coil. I was thinking more like .40-.42 myself. What do you think.

Would you believe that the MSD ignition retard box that Vortech sent was bad? Have to send it back tomorrow and hopefully, I'll have the new one in by next weekend. In the meantime, I have retarded the ignition back to 7 degrees BTC and put a tank of 110 octane in the beastie so that I could drive it some.

Saying this thing now makes some serious power (it was no dog before either) is like calling the Pacific Ocean damp!

Thanx, Frank.
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