ok to find the max lift of a spring you take the installed height (1.780 for example)minus the coil bind height(1.200) and that equals the max lift(.580)right? the reason i ask is because i just got these heads-http://store.summitracing.com/partde...5&autoview=sku

and it says that the max lift is .480. shouldn't it be .580? or am i missing something here?

 

Well....

You have to give the seal room from the retainer. Also you need to give the spring an adequate amount of clearance between the coils, please people don’t rip me a new one, but Speed Pro recommends .060". I do recognize that these are most likely a different brand of springs. Finally in some instances the retainers may be stepped and the inner spring's will be ~.100" less than the installed height of the outer spring.

I’m not meaning to pick on your heads. Please don't think so. But if you note, the diameter of the springs on those heads are 1.250. This is one of the major weak points of small block heads. Due to this smaller diameter the coils in the spring must be thicker in order to gain spring pressure. This in terms makes coil bind happen much sooner. Two ways to get around this are to go to a bigger diameter spring, or to go to a taller spring. The bigger diameter spring can become hairy due to the fact that, a careful machinist must cut the spring pocket out. Factory small block heads are notoriously thin in these areas. The taller spring can become troublesome because, valves that have a longer stem are also needed. This can make a valve job necessary. It also changes rocker arm geometry and longer or adjustable pushrods are not always needed, but should be installed. Proform makes a swell tool for checking geometry.

A good rule of thumb and one of my pet peeves is that people should buy a camshaft and then pick the springs that the camshaft manufacturer recommends. Too many (including myself) worry about max lift of a spring, when we should also be worrying about spring pressure and piston to valve clearance. I hope this long explanation clears up some issues, and doesn’t create too many problems.

 

yeah that helps alot. thanks for the quick response!!!

 

your welcome, i just managed to catch this while i was online

 

I have the exact set of springs that are on your heads in my basement, the spec sheet says .520 max lift.

These heads are good for .600 lift easily and the pockets are already machined for 1.47od springs.