I’m no machinist/engine builder like BillK and some others on the board but been around a long time and work on things for a living. From what I’ve seen .016”-.002” seems to be the target exhaust guide clearance for marine stuff. .003” sounds extreme to me. Also, ditch the pc seals.

I agree.. We are talking .001 here...It's probably on the looser side, but I don't want to spend my summer pulling heads...

.002” is on the looser side.

the problem is you put a ton of heat into the exhaust valve with the timing and then had no oil to it with the seals. lots of big chevy race motors dont even run any type of seal on the exhaust because there is not vacuum on them so there is no draw of oil. seems you are over compensating for a problem that can be solved else where i.e. the timing and seal.

Understood...I can call the machine shop on that and told them to hold off...Do I just remove the spring from the seal or switch to umbrella type seals?