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

[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?