88F15088 wrote:Should I try to get the holes machined into slots from the machinist or should I just use 5/16" pushrods with guides? Either way it sounds like I will have to make another trip to the machine shop. Do I need different lifters that would accommodate 3/8" pushrods?
The pushrods move towards the center of the head as the rocker pivots so the slot needs to go in that direction but the problem is there is less than 1/4" of material before you run into water jacket in that same direction and the hole already moved in that direction when it got enlarged.
My recommendation is to use a thick wall 5/16 pushrod with guide plates.
One advantage of using guide plates is you can align the rocker tip so it is center from side to side on the valve stem tip.
The 3/8 pushrod works with the same lifter as long as it has the same diameter ball end.