big base circle cam in stock elem.
 

Big base circle cam in stock elem. just found out that it is not legal in stock.glad i did not ruin my block. was talking to kevin and Jeff the other day at lunch about getting my block opened up for the big cam and kevin told me that they had a call in to the tech dept to get a final ruleing. Jeff called me back and said that it was (NOT) legal.

Re: big base circle cam in stock elem.
 

How can they change their mind now I thought this was a done deal a year ago.. Not that they will ck for it any way.

Re: big base circle cam in stock elem.
 

Until it's in writing it's only hearsay not a rule.

Re: big base circle cam in stock elem.
 

Well, isn't that just precious?

Anyone seen a ruling either way, in writing?

Re: big base circle cam in stock elem.
 

I wonder how many have machined blocks for 55mm and 60mm camshaft cores. :)

Does it apply to Super Stock too?

Re: big base circle cam in stock elem.
 

There would be a LOT of illegal SS engines if that were the case. Any cam, right?

Re: big base circle cam in stock elem.
 

That's the truth. Could change or be enforced area to area. If you spin a cam bearing and have to repair a block, that means your out?

Re: big base circle cam in stock elem.
 

Now that is funny! There is a difference between repairing a block and machining the camshaft tunnel to use a bigger diameter cam.

Re: big base circle cam in stock elem.
 

Jim i know me and Jeff were getting ready to get the blocks done and he called and they said (NO) Jeff bought the tooling and his machineist was ready and someone called Kevin Helms and said that it is not legal anymore.and Jeff called to confirm it. ED. STOCK ONLY!!!! IT IS LEGAL IN SUPER STOCK.

Re: big base circle cam in stock elem.
 

Last time I checked Teuton and helms are not Gracia and Bachelder. Sammy what did Bruce or Danny say when you called and asked them?

Re: big base circle cam in stock elem.
 

Trust me, they definately do check for it. And pulling the cam out is apparently necessary to measure it. Not much fun, and hard on the tennis elbow when your balancer is as tight as mine is. Fortunately I had a stock size cam bore but I had intended to go with a 55mm but just didn't get it done in time.

I have an email indicating the large core cam is ok as long as you aren't using roller cam bearings. I will try to find it and post it if I can.

Tracy

Re: big base circle cam in stock elem.
 

I've never done it, but pontiac has problems with cam bearings. If you spin one and do excessive damage to the journal how would you repair it? They don't make an oversize cam bearing for my deal. I think the 50mm would be logical for a repair.

Re: big base circle cam in stock elem.
 

A decent machinist could make a sleeve and the machining process would be similar to sleeving a cylinder.

Re: big base circle cam in stock elem.
 

NEXT THING YOU KNOW, FUEL INJECTION WILL BE ILLEGAL ON 69 CAMARO'S ?????????:eek:

Re: big base circle cam in stock elem.
 

Paul, you are assuming that you use a standard cam bearing and not a roller bearing, right? I believe that is the issue.

Re: big base circle cam in stock elem.
 

The first post was about "BIG BASE CIRCLE" cams. When someone has a minute could you please forward me a spread sheet w/ what the stock base circles are for everything amc,ford,chry.chevy,hudson (you never know) What if you have big power adder like a 4/7 swap cam? And it ends up being the same as a ford would something like that be considered as crossbreeding?How do you tell the car (driver) in say B stock auto that just got his 440,396,427 etc A#S drug down the track by a 2014 302 you have to go home because your base circle is to big.

Re: big base circle cam in stock elem.
 

Just talkin about a repair for a stock Pontiac block with standard cam bearings, that's what I thought Todd was referring to.

Re: big base circle cam in stock elem.
 

I guess I don't really understand the issue here....What is the advantage to a large bearing cam shaft, as opposed to a standard bearing...????? I understand how a roller bearing camshaft bearing might make a half a horsepower.....plus add to the longevity of the engine. but a standard cam bearing versus a larger one??????? then why do Mopar guys use smaller rod bearings (chevy)...??? I'm just saying

Re: big base circle cam in stock elem.
 

The issue here isn't the larger cam bearing, it's the larger base circle LOBE that the larger bearing register allows you to fit in.

Re: big base circle cam in stock elem.
 

Exactly!! Great post.

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

Re: big base circle cam in stock elem.
 

Granted they did ck yours how many more have they cked ?

Re: big base circle cam in stock elem.
 

So what's the verdict here? Roller cam bearings? 60mm tunnel? offset lifters? Lifter dia?


lot of grey area to sort thru

Re: big base circle cam in stock elem.
 

In the spirit of "there are no stupid questions" what is the advantage of a large base circle cam in a Stocker motor? I know in a Comp motor where they RPM 9500-10000+ My 396-325 never went over 6800 and if it did lose power. Thanks Learn me something.

Will Lamprecht I/S 65 396/325 HP in progress

Re: big base circle cam in stock elem.
 

Does this mean that a ford can have roller bearings as they are the stock size and a ford part number?

Re: big base circle cam in stock elem.
 

60 mm tunnel, offset lifters, lifter diameter. What are you talking about? You went back 9 months for this? Do you race Stock or Super Stock?

Re: big base circle cam in stock elem.
 

To quote Bobby " 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."
Dwight hit the nail on the head.
But you guys have forgotten about "The other Rule Book"
We may not be able to read it because "They Have It" It is called the " NHRA TECHNICAL POLICIES & PROCEDURES" manual. That is where the real rules that the Tech Dept follows are written. It pin points area like what is being discussed. Every Div Tech director should have one, somewhere & there should be one at every NHRA race. Between the "Rule Book" we get and their TECHNICAL POLICIES & PROCEDURES there should be no problem being consistent with rules.
BTY: This is the same manual that the AHFS rules and procedures are listed in.

Re: big base circle cam in stock elem.
 

You will see me this year


C/S and D/S Boss 351 Ford

Re: big base circle cam in stock elem.
 

It is all about making the valvetrain stable at the rpm you mentioned, you are correct, not every combo can run up there and make power, but some can


Nascar...... .875 dia, flat tappet, 60 mm 9000+ all day long with almost 0 valvetrain breakage


Most stockers have "square" lobe cams.....think about that for awhile


Edit....the rulebook specifies "lift" as far as I am concerned that is all they should be checking, weather its at the valve and/or at the cam

Re: big base circle cam in stock elem.
 

Only 8 days left, better hope for good WEATHER.

Re: big base circle cam in stock elem.
 

Offset lifters? In a flat tappet BOY that will keep you busy.LOL