Valve spring clearance

I just got my ComCam pushrods measuring tools and need to know what the best clearance would be for the valve springs.
This will be on a BBC

Thank, Art

 

What clearance are you talking about ? Is it clearance between coil at max lift?
Claude

 

Yes, the clearncce between the coils during maximum lift. Obviously, we want to prevent coil bind in anyway. Crane Cams says .060, but what does this mean, overall .060?

Art

 

Art, when they say coilbind they are referring to the point at which the spring will not compress any further. Most spring manufacturers recommend not less then .050" to coilbind from the point of maximum lift. Let's say for example, that the springs are installed at 2.00", you have .750" lift at the valve(actual). If the springs were said to coilbind at say 1.200 , then you would have .050 clearance to bind. These are just round numbers for illustration purposes. In todays high rpm, hi lift, agressive lobe world, we have found you are better off getting real close to coilbind(within .050"). It seems to leave the springs less room to get into harmonics, resulting in longer spring life. I hope this helps.......

 

Coil bind

Dan,

thank you for the explanation, that makes so much sense. I was on the right track and you confirmed it for me.

Art in Seattle

 

Art, It will give you higher spring pressures and will seem kind of tight but it is the way to go but you want to measure actual lift at the valve with a dial indicator. You would be surprised how deflection will affect things not to mention rocker ratios. The only way to know for a fact what lift you have at the valve is to actually measure it. I take coil bind plus actual valve lift plus .050 to give me a target installed height. It might take a bunch of shims to get the height you are looking for.