Rocker Clarification is up!!!

[mopar jeff]

Originally Posted by Jim Wahl

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."


.

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?

[Jeff Teuton]

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.

[Jeremy]

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?

[Jeff Teuton]

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

[Bill Edgeworth]

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.

[Larry Hill]

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

[denbreeden]

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


Dennis Breeden
A/SA

[theworm]

Originally Posted by mopar jeff

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?

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