the only Mod that is needed for the lump is to remove the Boss. But it is also true that by going to a larger valve will also increase the flow gain. and by the same token so will Unshrouding the valve stock Or other wise.
What i wanted to find out Is what Gain is the groove itself With OUT the increase in compression.
I know the theory behind it. It's not really much different then cutting a groove in a pop-up piston to get the spark/Flame to the other side of the dome. as the groove in the squash area is direct the fuel mix back to the flame or to induce a swirl effect in the combustion chamber, not much different then useing a ball cutter to under cut and unshroud a valve to induce a swirl this was done many many years ago i seen this back in the 70s when I first started racing. and It's not anything you see done to a head anymore either. This was the way the machine shop was to have done my head But for what ever reason He didn't or just for got to unshourd it. So now once i get the motor back I will pull the head and disassemble it to finish a cut around my valve guide and to make sure it was unshourded one way or another.And I may go back and raise the port a little more(ceiling wise).
And as for ur2cents we all have it LOL so no harm in adding it. Besides we all have to ,To find the answer we're looking for right.LOL
But something else I have to add, and is due to the factor of rasien the compression as with any combustion engine carbon is always building up and over time it to can require a Much Older motor to need a better octane fuel. But normaly this goes unnoticed because it's not enough change really to warrant it as with each fresh tune-up everything is always reajusted to account for the Age or any carbon build up that maybe going on.Again the old age trick there was to either dribble water or Tranny fluid down the carb to Help BURN off the carbon build up.I don't know for sure how well that really worked But Boy it sure did smoke for them few minutes.LOL But that to was the idea behind a water injection unit was to slow the burn down to make the burn more efficient. And to help improve the MPGs which I did try for a while myself back in the 70s. But i got tired of having to refill it,It never seemed to last as long as a tank of gas. And was always running out before my Tank did LOL.
God doesn't like ugly.
