Re: Rocker Clarification is up!!!
 

I have a friend who worked in a job shop that made the pivot pins for aircraft wings during the Vietnam War. I can't post here what went on in that shop.

Re: Rocker Clarification is up!!!
 

We need to be carfull of what we ask for.
I am trying to get ready for next year and I've checked several rocker ratios.

Com Cams 1.5's came out between 1.526 and 1.572 all over 1.5.
Pro Comp's 1.6 came out 1.506, some over and some under the 1.5.
Crane 1.5,s came out 1.427, all under the 1.5.
There was considerable differances from rocker to rocker on all of them.

What they say there ratio's are may not be what they really are.

Jerry Stk.4168

Re: Rocker Clarification is up!!!
 

Maybe the old stamped rocker arms aren't so bad after all.

Re: Rocker Clarification is up!!!
 

Just wondering, what was your test procedure?

Re: Rocker Clarification is up!!!
 

SECTION 10A: STOCK CARS, ENGINE:1, ROCKERS ARMS (Page 5) (1/19/2012)
"OEM or a Aftermarket rocker arm permitted. Either adjustable push rods or adjustable OEM rocker arms permitted on any application, but not both. Needle/roller bearing pivots and roller tips are permitted for all applications. Must remain same design as original application (i.e. stud mount must retain stud mount, pedestal type must retain pedestal type and shaft type must retain shaft type. Stud girdles prohibited.) Stamped steel OEM and OEM-type rocker arms may be reinforced."


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Re: Rocker Clarification is up!!!
 

All good points by everybody here...With all the trouble...almost makes you want to yearn for the old days...the real STOCK Eliminator...(lift-duration-overlap-spring pressure...and REAL stock rockers!)

Re: Rocker Clarification is up!!!
 

How about this. Make sure your rockers are the same configuration like the book says. Make sure the ratio stamped on the rocker is the same as the 'blueprint specs', and make sure your cam passes with a solid or blocked lifter. What am I missing here.

Re: Rocker Clarification is up!!!
 

You all know Jeff is right. If you want to take advantage of the new rocker rule you will have to do your homework! Jim


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Re: Rocker Clarification is up!!!
 

Forget the ratio stamped on the rockers. Those numbers evidently mean nothing. Be sure to measure the lift at the retainer AND at the lifter so you can do the math when you check the ratio of the rocker arms yourself. What should be a simple bolt-on is turning out to be a real cluster that no one ever expected.

Remember...watch what you wish for, it might just come true!!!!!

Re: Rocker Clarification is up!!!
 

I think it's a real cluster for those that still ask to go to the bathroom...

Re: Rocker Clarification is up!!!
 

We can't control manufacturer's tolerances. I mean REALLY... 1.7 ratio... give or take .05.. ?
Who gives a $%#T ? !
Lift at the retainer below blueprint spec... studs, pushrods, springs, all of the specified configuration and mounting. We haven't changed valves, hacked up the heads, or gone over factory lift at the valve.
WHAT is the problem ? !

Re: Rocker Clarification is up!!!
 

Rocker arms, and valvetrain geometry in general, remain as two of the most misunderstood areas of a race engine. About half of what people think they know about the subjects is wrong. Maybe more.

That's not directed at you, personally, Aubrey, but rather a general statement.

Re: Rocker Clarification is up!!!
 

Yeah ? YEAH ? !
HEE HEE !
maybe I know less than that ?

I'm just sayin... It seems to me that much of the reason NHRA removed the spring pressure and duration rules, was to simplify inspection and enforcement. Of course it changed things. This rocker allowance can be simplified too. Merely have a ratio tolerance... IE; +/- .05, and if lift at valve checks ok... we're good.
I understand that "ingenious" folks may discover advantages one way or another. Positioning of the fulcrum-point for one. Shaft rocker setups are probably more stable, but stud rockers are more user friendly.

I dunno
maybe I'm just simple ?!

Re: Rocker Clarification is up!!!
 

There already is a rocker ratio tolerance, it is +0.0/-x.x, as they don't seem to penalize anyone for not having enough ratio. You can have the stock blueprint ratio, or less, but not any more than stock. That's tolerance enough, a + 0.0/-x.x is an industry accepted tolerance range.

NHRA checks lift at the retainer, then divides by lift at the cam to get rocker ratio. I'm allowed 0.520" at the retainer, I run 0.518", with 0.306" lobe lift on the cam, for a 1.69:1 rocker ratio.

In Stock, we have to use pushrod length to correct lift, in most cases. That does not change, it's just that with aftermarket roller rockers, you'll need to start from scratch, and get the pushrod that gives you the correct lift, without exceeding the allowed rocker ratio.

Re: Rocker Clarification is up!!!
 

How come when I look at NHRA's amendment page this part is crossed out?

Either adjustable pushrods or adjustable OEM rocker arms permitted on any application, but not both.

Does that mean that part of the rule no longer applies?

Re: Rocker Clarification is up!!!
 

They threw me out last year for having 1.65 rockers and the spec said 1.60. The cam passed. Up to yall. I got 1.60's on the car now.

Re: Rocker Clarification is up!!!
 

Jeff, I thought that was just to keep you from getting horsepower!
Jerry

Did they really check or just see what was on the rocker?

Re: Rocker Clarification is up!!!
 

They read the rocker stamp. And when I went to Indy, they read it again.

Re: Rocker Clarification is up!!!
 

Jeff;
In my opinion it was very unjust that you got tossed for what was written on the rocker arm. As Allan mentioned valve train geometry is a very misunderstood thing and just because they say 1.65 on them does not mean they are that ratio on your engine. In many (most) cases when you are running longer than stock length valves you can never achieve the advertised ratio of the rocker unless you run an extremely long pushrod and totally mess up your geometry.
For those that are not familiar with the circumstances that cause this let me explain; many engines like Jeff’s Mopar engines or my Pontiac stuff have converging angles between the valves and rocker studs or pedestals in the case of the Mopar engines. So when you run a longer valve than stock the distance from the pivot point of the rocker to valve tip decreases effectively reducing the rocker ratio. So with longer valves those rockers with 1.65 written on them may not even be 1.6.
I believe the reason the factory designed them this way is to reduce side loading on the studs at maximum lift (maximum valve spring pressure)
So this is just a couple of the issues you have to consider when figuring out your spring/valve/retainer combination.
I’m betting when they tossed Jeff they did not check his rocker ratio they based their decision on what was written on the rocker arm???
Aubrey; If you look at what I have said there is more of an issue with how we use the arms compared to conditions under which their ratio was calculated than a tolerance issue.

Re: Rocker Clarification is up!!!
 

Bill I think you can use longer than stock valves in super stock, but not in stock.

Re: Rocker Clarification is up!!!
 

Any aftermarket steel valve permitted, must retain stock head and stem diameter is what the rulebook says, nothing about length.


Dennis Breeden
A/SA

Re: Rocker Clarification is up!!!
 

Longer than stock aftermarket stainless steel valves ARE LEGAL in stock in both NHRA and IHRA and have been for many years.

Re: Rocker Clarification is up!!!
 

OK! So everyone is right! The rules are clear as mud, but shouldn't be that hard to understand.

Manufacturers tolerances are suspect, so everyone needs to have a little cushion so you don't go over the spec. I don't have the capability of checking the "true" ratio of each of my rocker arms, but if each one is different, I'll have to check the true lift at each retainer, and hope I get 16 measurements that are the same. It's quite possible that will take more than 16 rocker arms to accomplish. Maybe I'll just be happy if they're all below the maximum lift.

I'm really not trying to be obtuse here, just trying to understand why the rules have to be written so vaguely that they invite all of this discussion! Most every other aftermarket part is identified by number in the Guide, for a reason.

Lew

Re: Rocker Clarification is up!!!
 

You don't? Then you're just asking for trouble!

Re: Rocker Clarification is up!!!
 

Its easy enough to do. Check all 16 rockers on one valve, figure the true ratio of each rocker, then check the rocker with the largest true ratio on all 16 valves.

Re: Rocker Clarification is up!!!
 

Lew,
The discussion is kind of becoming apples and oranges.
The points I was trying to make are;
1 They should not be tossing people without actually measuring the rocker ratio on their motor
2 Tolerance and advertised ratio are two different things and you need to consider both issues because advertised is often not what it works out to be in real life.
And further to what Dennis and X-tech man said I think the reason they relaxed the valve length rule is that it was very difficult for some racers to find a spring that would give the needed seat pressure and rate and fit all the height, diameter and configuration criteria. (Another can of worms to squawk about for those who don’t like our current spring pressure and duration rules or lack of rules that is)
And as Billy mentioned you better be checking every single one for two reasons; to make sure you are legal and not leave anything on the table.
Doesn’t all this talk about checking stuff make you want to run out and buy a 3 or 4 valve or a V10 stocker? LOL

Re: Rocker Clarification is up!!!
 

thats what it sounds like to me they dont care anymore about this.

Re: Rocker Clarification is up!!!
 

Because most of you guys try to make something out of nothing. Why bother changing rockers in the firt place if your not breaking rocker arms and you still going fast ? The rocker arm is NOT going to give you some out of no where 50 plus HP. The best I have seen or heard of is approx a 3 HP gain on a good DTS dyno and that was from back to back testing of some really screwed up OEM rockers vs a nice set of alum. roller rockers that anyone could afford and buy. Just make sure you lift is correct(not over) and your not trying to use an under cut cam and over ratio rockers or you WILL get cought and DQ'ed..

Re: Rocker Clarification is up!!!
 

Can this rocker be in Aluminum or steel?

Re: Rocker Clarification is up!!!
 

As per a conversation with Danny at the PRI Show, both are legal. Jim

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