Technical sbc valve springs??

Rebuilding a set of 041 sbc heads, measured the spring pressure and they appeared to be very weak so decided I would buy new springs, went to Napa figuring this would be an easy one and they show different part numbers and different heights for the intake and exhaust? Yet when you look at places like Jegs and Summit most the aftermarket guys sell them in sets of 16 all the same height? What gives, why the difference?
This will be a very mild build, stock spec springs should be plenty for the cam we are using...

 

if it has valve rotators or not will affect the length

 

the springs we are replacing have no rotators, just keepers and retainers?

 

If it were me I would replace all 16 valve springs and that is exactly what I did. HRP

 

36-3 window is correct, some years have rotators and some years don't. Look at the mill you tore down and see if it has t rotators, if it does not then choose a year that has the same length springs.

here is my general rule of thumb on a stockish small block, I buy springs and valve gear for an L-79 motor unless I think I am going to run a healthier cam than a 350( *375 ) horse cam then I use z-28 springs. that leaves a little room for a healthier cam at a later date as long as I don't decide to go balls to the walls on the cam shaft.

* we used to call the L-79 a 375 horse 327 when I was young because with just a good tuning you could squeeze 375 out of one.

 

They "should" be same height with no rotator used. Best to measure the actual height on your...heads.
As you check to verify the springs, put the stronger springs on the intake (heavier valve).

Mike

 

Depending on the year and casting number. The valve spring can be short with a rotator. These castings will take the same spring height across when the rotator is removed, as the spring seats are all factory machined the same height.
Newer designed heads (mostly post 1970) use all the same length springs and the exhaust spring seats are cut deeper to allow for the rotator. Thus you must use spacers/shims ( approx .100") on these exhaust springs to allow the same installed height.

 

always buy valve springs to match the cam you are going to use. this applies to stock cams as well as aftermarket ones.in todays world of low zinc oils do not use high spring pressures.