Flathead Question

Any one using Champion RC 12 YC plugs in Aluminum Heads. If not what are you using to compensate for the almost 1" thread depth in plug holes?

 

Just about ALL the aluminum Flathead heads should be "Fire-Slotted" at the spark plug holes!

Have never installed a set here without this procedure!

We use a mill to accomplish the job, it can be done by hand (a very steady one) and a die grinder!

Thanks, Gary in N.Y.

P.S. Here's a few shots of a very recent pair of the new Edelbrocks being machined! The photo on the left shows the machining setup, the right shows both the valve pockets AND "Fire-Slots" finished.

 

That is the plugs Edelbrock recommends for those heads.

 

GOESFAST, "Fire-Sloted" are you talking about recessing the plug hole in the combustion chamber to do away with the threads that would extend below a short reach plug such as the H-10 was? Enlighten the old man, never heard of this but sure willing to learn. Explain what you do and what it accomplishes if you don't mind.

Thanks

 

I would like to learn more info also, plus close up photos. Thanks.

 

Exactly, that is the reason for the procedure!

It eliminates the first few threads, allows the spark access to the "charge" with no shrouding. It also keeps carbon from building up in "empty" threads.

The machining operation appears as a "tear-drop" shape when finished correctly, from the center of the plug hole and towards the pistons.

Most early aluminum heads had "shorter" plug threads, the newer heads are approx 1.000" long when cast!

I'm not aware of any (Hot-Rodded) Flathead owners using any of the H-10 plugs anymore, most are of the 5/8" socket, 3/4" long-reach, and gasketed series nowadays!

(O/T) We now also have the tooling to "dowel-pin" the aluminum heads to the blocks, identical to the SBC's, using (2) 5/16" dowels!! This "pinning" tool is an incorporated part of our block plate, used for finishing honing the blocks!

Thanks, Gary in N.Y.

P.S. I don't have any add'l photo "close-ups" of the machined areas! Here's a link to some Flathead photos we've built and performed the machine work on, for many customers!

http://good-times.webshots.com/album/567557661EjkkPG

 

GOSFAST: The term "Gas-Slotting" is what threw me off. What you describe is a must for fuel, extra threads not much of a problem with gas in my experience but sure doesn't hurt any thing if you are going to go with the shorter reach plug. Champion doesn't make the H-10 any longer to my knowledge. Stud holes in aluminum heads today are oversize by quite a bit so pinning them as you describe is not a bad idea at all. Interesting,

Thanks for the feed back