Blown motor, Valve seals

For my SBC, do i need valve seals? I ordered my valves today, so i'll be assembling my heads here soon.

I've always ran them before, but I've also heard on a high effort blown machine, that they aren't recommended. Why?

 

I've run with them and without. Currently, most of our motors do not have them on. I have seen no difference.

 

Cool. thanks for the feedback

 

As to why not,

On a positive displacement blower ( IE Roots ) there is always greater than atmospheric pressure in the intake port so oil will not get sucked into the port like on a naturally aspirated, nitrous , or low boost centrifigal deal.

Richard Gavle

 

don't run seals... for one the positive pressure will keep the guide from leaking into the port plus you will want more vs less lube on the guides and seals won't help in that regard

 

Even at idol and after a burn out?