6 bbl holley. Startup immediately at 1500 rpms then keeps climbing quickly. Finally cut it at 4k. Tried to WOT to reset fast cam lever...nothing. Kept increasing. Something binding? All I did beforehand was remove/reinstall secondary springs to see which ones they were and manually forced linkage forward to check how dirty underside of outboard plates are. What caused this rapid and continuous increase in rpms? Any more info u need, let me know.