Rocker Arm Ratio

[Bill Diehl]

Originally Posted by Alan Roehrich

Correct, Dwight. All sorts of manipulations are possible if you only check lift at the valve.

No matter what anyone does to the valvetrain they not going to be able to exceed max lift. period!

There is no doubt you can gain lift and duration at different points in the curve, but, that's no different than grinding it into the cam.

With that being said, there is NO WAY you are going to be able to open the valve any farther than max lift...and that's what we are talking about here.

Now, without a doubt you can make the engine much happier up top in the rpm range by correcting the valve train geometry and I am not talking about rocker geo. I am talking about the entire valvetrain.

At the end of the day who cares what the valve does when it leaves the seat...as long as it does not open any further than what the spec says is the max. where ever that just happens to happen in the entire curve

[Alan Roehrich]

Originally Posted by Bill Diehl

No matter what anyone does to the valvetrain they not going to be able to exceed max lift. period!

There is no doubt you can gain lift and duration at different points in the curve, but, that's no different than grinding it into the cam.

With that being said, there is NO WAY you are going to be able to open the valve any farther than max lift...and that's what we are talking about here.

Now, without a doubt you can make the engine much happier up top in the rpm range by correcting the valve train geometry and I am not talking about rocker geo. I am talking about the entire valvetrain.

At the end of the day who cares what the valve does when it leaves the seat...as long as it does not open any further than what the spec says is the max. where ever that just happens to happen in the entire curve

Because it is not maximum lift that matters. It is how fast you accelerate the valve, and how much area under the curve you generate.

[Bill Diehl]

Originally Posted by Alan Roehrich

Because it is not maximum lift that matters. It is how fast you accelerate the valve, and how much area under the curve you generate.

Exactly.

but that's not how its spelled out in the book, it says lift...some have an advantage with lifter dia. which accomplishes the same thing.

So, are they measuring lifter dia. or are the .842 guys using .875 and larger stuff?

[Doug McCue]

Originally Posted by Bill Diehl

Exactly.

but that's not how its spelled out in the book, it says lift...some have an advantage with lifter dia. which accomplishes the same thing.

So, are they measuring lifter dia. or are the .842 guys using .875 and larger stuff?

During a tear down are lifter diameters measured?

[Aubrey N Bruneau]

I use 1.7 ratio in an engine that calls for 1.75. The difference has been made up through the cam lobe. Lift at valve checks about .007" under my max allowed.
I have twice asked NHRA about this. As mentioned, they're concern was higher ratio rocker, and of course the actual lift measured at the valve.

just my experience... which is limited

[Dwight Southerland]

Originally Posted by Bill Diehl

No matter what anyone does to the valvetrain they not going to be able to exceed max lift. period!

There is no doubt you can gain lift and duration at different points in the curve, but, that's no different than grinding it into the cam.

With that being said, there is NO WAY you are going to be able to open the valve any farther than max lift...and that's what we are talking about here.

Now, without a doubt you can make the engine much happier up top in the rpm range by correcting the valve train geometry and I am not talking about rocker geo. I am talking about the entire valvetrain.

At the end of the day who cares what the valve does when it leaves the seat...as long as it does not open any further than what the spec says is the max. where ever that just happens to happen in the entire curve

The argument is kind of like saying that if I use fiberglass fenders, bumpers, hood, trunk lid and doors on a car that look identical to the original and make the car weigh correctly, it doesn't matter.

The issue behind most regulation changes is basically the cost. If you want to add another area of expense to building a competitive car then keep saying it really doesn't matter. The fact is that there are mechanical advantages to be gained by combining rocker arm ratio changes with camshaft design and valve springs that result in more power when the lift at the valve is restricted. If you are seriously comfortable with providing that advantage to certain racers with the resources to leverage the technology then it makes Stock eliminator a little further away from being an entry level venue. And it becomes more difficult for the self-sufficient racer who builds his own stuff to keep up.

[Bill Diehl]

Originally Posted by Dwight Southerland

The argument is kind of like saying that if I use fiberglass fenders, bumpers, hood, trunk lid and doors on a car that look identical to the original and make the car weigh correctly, it doesn't matter.

The issue behind most regulation changes is basically the cost. If you want to add another area of expense to building a competitive car then keep saying it really doesn't matter. The fact is that there are mechanical advantages to be gained by combining rocker arm ratio changes with camshaft design and valve springs that result in more power when the lift at the valve is restricted. If you are seriously comfortable with providing that advantage to certain racers with the resources to leverage the technology then it makes Stock eliminator a little further away from being an entry level venue. And it becomes more difficult for the self-sufficient racer who builds his own stuff to keep up.

Its not always about the money, although that makes a pretty good case as an excuse.

the fact is, some folks just have more talent then others do when it comes to engineering out there project.

I do see your point as being an entry level class, and for those that have the resources and/or knowledge to explore the technology advancements should just move on up the ladder into the faster less restrictive class

I get it, thanks