Why did nhra change the cam and valve spring rule in 1985?

[Billy Nees]

Originally Posted by SSDiv6

Billy, there is a lot more in camshaft design and in the early days, it was mostly hit/miss. Camshaft technology has taken great leaps with the advent of computer modeling.



The big difference on the new generation Cheater camshaft is they have faster ramps with bigger numbers in 0.200" lift area.

I agree with you completely that with the advent of "CAD" camshafts there have been great strides in "Stocker" performance potential BUT it is still at a cost! No matter where you increase the opening and closing rates on the cam the valve MUST follow the ramp and the rate of opening or closing. It still comes down to a compromise. When and where ever you increase the speed of the valve event you have to have a spring rate that will allow it to follow the lobe. So you will STILL need better lifters, pushrods, springs etc. to get the job done. And you still have to spin the motor accordingly.

[X-TECH MAN]

Originally Posted by Billy Nees

I agree with you completely that with the advent of "CAD" camshafts there have been great strides in "Stocker" performance potential BUT it is still at a cost! No matter where you increase the opening and closing rates on the cam the valve MUST follow the ramp and the rate of opening or closing. It still comes down to a compromise. When and where ever you increase the speed of the valve event you have to have a spring rate that will allow it to follow the lobe. So you will STILL need better lifters, pushrods, springs etc. to get the job done. And you still have to spin the motor accordingly.

Might as well build a Super Stocker. Roller lifters cost less, roller rockers are less prone to breakage, Your going to sling the snot out of the engine with the rules the way they are so use better stronger parts and the heads and intakes are ported anyway and probably cost less from not having to hide what you do to them......lol.

[SSDiv6]

Originally Posted by X-TECH MAN

Might as well build a Super Stocker. Roller lifters cost less, roller rockers are less prone to breakage, Your going to sling the snot out of the engine with the rules the way they are so use better stronger parts and the heads and intakes are ported anyway and probably cost less from not having to hide what you do to them......lol.

Under your premise, let's move the current Stockers to Super Stock, then bring back Modified Eliminator and move all current Super Stockers and finally bring back Pure Stock again. LOL!!!

[X-TECH MAN]

Originally Posted by SSDiv6

Under your premise, let's move the current Stockers to Super Stock, then bring back Modified Eliminator and move all current Super Stockers and finally bring back Pure Stock again. LOL!!!

LOL....Well the A/SA and AA/S are quicker than the Pro stocks were in 1970 (or the 1/4 mile is shorter) on little bitty 9 inch tires, "stock heads", OEM bottom ends, and they weigh more. Its called "Progress"

[SSDiv6]

Originally Posted by X-TECH MAN

LOL....Well the A/SA and AA/S are quicker than the Pro stocks were in 1970 (or the 1/4 mile is shorter) on little bitty 9 inch tires, "stock heads", OEM bottom ends, and they weigh more. Its called "Progress"

I was watching some old movies in You Tube and suddenly realized that some of the lower class current Stock Eliminator cars are running faster than the old Modified Eliminator cars that had aluminum heads, tunnel rams and twin carbs!!!

[X-TECH MAN]

Originally Posted by SSDiv6

I was watching some old movies in You Tube and suddenly realized that some of the lower class current Stock Eliminator cars are running faster than the old Modified Eliminator cars that had aluminum heads, tunnel rams and twin carbs!!!

And what does that tell you? Its not all tire technology and ring packs....Maybe the air is better today than back in the 60's and 70's?

[Alan Roehrich]

Originally Posted by X-TECH MAN

And what does that tell you? Its not all tire technology and ring packs....Maybe the air is better today than back in the 60's and 70's?

It's any number of things. Granted valve springs have allowed a lot. But clutches, carburetors, torque converters, headers, and transmissions have come a long way. There's a ton of things that have gotten better, and racers have gotten smarter because there's more information available as well. Information and knowledge make a lot of HP.

[cudadoug]

Originally Posted by X-TECH MAN

Might as well build a Super Stocker. Roller lifters cost less, roller rockers are less prone to breakage, Your going to sling the snot out of the engine with the rules the way they are so use better stronger parts and the heads and intakes are ported anyway and probably cost less from not having to hide what you do to them......lol.

Couldn't have said it better! While I'm not a "S/S or stocker racer", I do follow it pretty closely. There are quite a few stocker racers who DO believe a Super Stocker makes more $EN$E. Less cost, more contingency dough (IF you can paid!) and often less car counts...

I also believe that the valve spring rule was the turning point to begin the RUIN of the class and it's original concept.

[Rick Leininger Jr.]

Originally Posted by Billy Nees

No matter where you increase the opening and closing rates on the cam the valve MUST follow the ramp and the rate of opening or closing.

IF you use the ceramic lifters.

[SSDiv6]

Originally Posted by Rick Leininger Jr.

IF you use the ceramic lifters.

Yep...in the past I have addressed the subject of valve train dynamics and camshaft lobes in the Tech section...there is a lot more on new camshaft designs that do not require the high spring pressures being used today...