Re: big base circle cam in stock elem.
 

I don't understand how anyone can think that a cam that doesn't fit in the STOCK bore can be considered legal for STOCK Eliminator. But of course, that ship sailed loooong ago.

Re: big base circle cam in stock elem.
 

If it's not in the rule book it cannot be enforced. If that was the case they could make up any rule they wanted to and bounce someone just because they wanted to.

Re: big base circle cam in stock elem.
 

I found the reply letter from Pat Cvengros regarding the cam journal size, of course this does NOT address the base circle of the lobes directly (as is the topic of this thread) , but if someone is getting a large base circle lobe on a stock core size camshaft in a vintage BBC I would sure like to know.

Here is the letter:


Pat Cvengros <pcvengros@nhra.com>
6/9/10
to Tracy

Tracy,

The camshaft may be of the large journal design; the bearings however must be a Babbitt type, non-roller design.

Pat Cvengros

Technical Services Representative

(626) 250-2295

Re: big base circle cam in stock elem.
 

That's not quite the way it works. The rules are written and enforced in a "positive" manner. That is, if the rule book does not say you can do it, then it is not allowed. Plus, according to the paragraph under "BLUEPRINTING" in the stock cars section, it clearly states "Stock factory OEM components (unless otherwise specified) must be retained and remain unaltered . . . " (emphasis mine). That's a good basis for it not being allowed.

Re: big base circle cam in stock elem.
 

Ouch must have hit a nerve here!!!!!!!!!!!!!!!!! If you look at the the first post you will notice that the block in question needed to have the cam bore machined to fit the larger cam. I believe it is common knowledge to say when you upgrade your engine to a {big base circle cam} that you are enlarging the cam bores in the block to accept a larger cam bearing. The good people grinding todays competition cam profiles do all they can to allow the largest base circle obtainable within the limitations of the lobe lift and cam journal diameter.

Re: big base circle cam in stock elem.
 

From a distance if they are smart. Ha Ha

TP

Re: big base circle cam in stock elem.
 

"big base circle" and 55MM tunnel is two completely different items. I think the person who started this post is referring to modifying his block for 55mm camshaft.

Re: big base circle cam in stock elem.
 

Exactly what Tim said, the post was titled wrong
It should have read- Big cam bearing journal cams
Illegal in stock. But with that said, Pedigo has a
Letter to state the opposite, if there is a question
Nhra should post something so everyone can see
Not just a select few. As far as the rule book I
Have never seen where it is legal and if its not
There it's supposed to not be allowed.

Re: big base circle cam in stock elem.
 

Historically it has not been enforced like that. Guys have pushed the envelope with parts and have gotten away with it. Some have been challenged at the track by tech officials, then the challenger is overruled. So the positive manner enforcement, is not being held up everywhere.

Sounds like roller bearings are the issue, not the size of the base circle/bearing journal.

Re: big base circle cam in stock elem.
 

Dwight hit the nail on the head, if it doesn't say it is allowed in the rule book, it isn't,, sorry Bobby

This is certainly a grey area topic though,, there are plenty of large bore cams out there, and i never saw anyone tossed for it, but I honestly don't know if anyone has ever been checked for it.

According to the letter that is posted here, it's A OK. unless of course they change their mind. So we simply need to hear from NHRA regarding this issue, because someone obviously told Jeff and Kevin larger bore cams are not allowed.

Thanks Sammy for starting the thread