[unruhjonny]

I understand the confusion all too well, and ended up deciding that I am building my car around the PSMCD rules;

Factory Stock/Pure stock = NHRA; their rules are printed and have some flexibiilty for cars never factory built (eg: 1970 RAIV Formula 400)

F.A.S.T. = in my book this one is essentailly a 'stock appearing' race where the deeper your pockets, the faster you go.; F.A.S.T. = Factory Appearing, Stock Tire; if it isn't seen or if it looks stock, you're good to go.

PSMCD = the group with the most stringent rules, and in my interpretation has the potential to be the funnest of the lot. It's all about your car, and essentially comes down to the hp/weight along with the driver.

The camshaft rule change has lessened, or almost eliminated my search for a good 067 cam for my car - I didn't want to go with the replacement, which is essentially a 066 cam, and the few 067 cams out there are not cheap. I had one gent here offer me an NOS one, but at the time I declined the offer.
This rule, as I see it should permit me to use a readily available 068 cam - this has no extra lift, but does have more duration, but may be a financially feasible step-in replacement camshaft.

[ponyakr]

"...The camshaft rule change has lessened, or almost eliminated my search for a good 067 cam for my car..."

Yes, and unless you just wanna run something that's similar to a factory grind, there is no good reason to run one, from a performance standpoint.

As was just recently posted, the NEW cam rule is a minimum vacuum requirement, ONLY.

That means to me that the lift & duration numbers of your cam does not make any difference, at all, from a rules infraction standpoint..

Instead, ONLY the vac number @ 1200rpm will be checked.

As mentioned, I learned from my dirt track days that you can run a pretty healthy cam, & still make the minimum vac requirement.

I've even seen some sbc dirt track cams advertised as cams that will make more vac, for classes with the min vac rule.

BUT, I've never seen any Pontiac cams that were specified as vac rule cams. So, you'd need to do some vac testing in your engine, with different cams, to find out how much cam you can use & still pass the vac test. I'm guessing that the size of the cam you can legally run will surprise you.

This cam testing would be VERY interesting to me. Wish I had the budget to take part in it myself. If I had the money, I'd even buy some possible cams for someone to try.

Maybe some of the experts here can post some of the decent high vac HFT cams they have tested.

I haven't ever really tried to learn what cam specs produce more or less vac. I assume that a bigger LSA would produce more vac. And I assume that variable duration lifters, like Rhoads, would increase vac @ 1200rpm. And, I assume that thinner oil will increase the bleed down rate. But, I'm no expert.

With all this in mind, I think the 1st cam I'd look at is the Summit 2802. It has a 114° LSA. With Rhoads lifters & thin oil, it MAY pass the vac rule. If not, it should at least let you know how close the vac is, either above or below the legal amount.

https://www.summitracing.com/parts/sum-2802

The Voodoo cams should also produce good vac, along with their good performance. A combination of Voodoo, Rhoads, & thinner oil MIGHT be a good high vac, high power combo.

https://butlerperformance.com/i-2445...-10510702.html

https://butlerperformance.com/i-2445...-10510703.html

I've read that some cam co will grind a cam with a different LSA than advertised. So, if a particular cam would make big power, but just barely miss the vac min, it might be that an LSA increase of a few degrees, would make it a legal & good cam for this app.

I think I've also read that slightly advancing or retarding the cam timing can affect vac.

As mentioned, I think this is very interesting. You'd be trying to find the HFT cam that would produce the quickest ET in your car AND that would pass the vac test.

But, if min ET is not the goal, this info is useless.

[Mcronk]

I understand cars can be built for class racing and a lot never left the factory with the drivetrain they are raced with. I just found it odd he claimed it to be a 73 SD 455. Car originally could have been a 350, 400, or possibly 455 D port as well. He could have installed the 455 SD in the car.
Maybe we can tell by the class designation?

My interest in class racing goes back to 1980 when I watched Qjet powered engines run in the 10s. I think it would be cool to restore some of those old racers.