XXO "specialty head" ?

[RichFox]

Many of the V4 engines do have more mains welded into the block. Welding more mains into a GMC block came up a few years ago, but no one was prepared to actually do it that I know of. And so as far as I ever heard no ruling was made as to legality of that modification. As I read the rule book all it says is that the head may be cast, billet or weldment. That pretty well coveres it as far as I know. I see nothing about head bolt arrangement except that OHC heads can not be used even if they bolt on. So I would say "Go for it." No body in tech is going to be impressed if you tell them "Rich Fox said it was OK." Speaking of welding what about some of the flatheads (Ron Main amoung others) that have had the airflow greatly improved. That's not so far removed from using a later stock (Cheap) head.

[maguromic]

Even if you had to run the stock head bolts you could bolt an adapter and then bolt the head to the adapter. Unless you also ban adapters it would be hard to enforce the head bolt rule.  When I was talking to Russ last year he did mention that the cam could not be moved more than a thousands from the stock location. If you really wanted to get wild build a four valve head that ran with push rods like Bruce Crower did with the Nash.

[Unkl Ian]

Important distinction: is it "the cam must remain in the block",
or "any rocker arm head"?
Not the same thing - perhaps some will see where I'm going.

Converting an OHC cylinder head to pushrods and rocker arms ?

If it was actuated by a single cam, in the stock location,
sounds like it meets the rule.

[RichFox]

You might be able to convert an OHC head to pushrods. But it might be hard to find a place to run the pushrods that isn't taken up with ports and such. thats one of the big reasons for going to OHC. Anyway, why would you want to? If you cut up two after market aluminum heads and welded them to correct bore spacing, you might be able to bore holes and weld in bosses to relocate the head bolts to line up with the block. I know it would have worked on my Plymouth had I wanted to spring for an aluminum head.

[Unkl Ian]

Easy to find a 4 valve OHC head, but can
you find one big enough to feed a "big" motor ?

Maybe some of the Ford 4.6/5.3 stuff.

[roygoodwin]

Kinda related, but not exactly, but there's some interesting stuff here < http://www.uncommonengineering.com/index.html >  anyway.

About 1/2 way down the page there's "BLOWN FLATHEAD FORD,  SOHC 3 VALVE / 3 CAM "F" HEADS UNDER CONSTRUCTION FOR THE ULTIMATE SUPERCHARGED FLATHEAD 8BA FORD V-8"
& way down the page theres "Three Billet Steel Main Bearing Webs Added to 4 Main Bearing Block", where they've added main bearings without welding. Probably won't work for every engine, but interesting anyway.

roy

[RichFox]

My point here is that there are people in the SCTA that have the means to have an unlimited GMC head carved out of a billet if they decide to. Looking at some of the V4 engines I think it's just a matter of time until someone will. So if that is legal the use of cheap junk yard heads to move into XX should not be restricted.

[rebelce]

I have to agree, big bucks almost always takes it. One thing I've learned from working with Leo, is that almost anything can be adapted to work if one try's hard enough. You are a great example of that.  I'm not sure who could (or would) give a defining answer to this.  I wouldn't object either way (stock bolt pattern or re drilled).  I just want to know what's legal and hopefully to stay within the spirit of vintage racing.