I thought it may be the same setup. I'd of bet a 100 bucks it was the check valve. Like I said above this thing should want 35/80-90 pill for sure. I used to run the 0 1/2 pump on a sb that might of made 650 and had no issue. Did you guys check and make sure the pulleys are right, meaning its not over driving the pump ?
No egt I assume ?