Has anyone converted a 250 crossflow to serpentine belt drive. I cant keep V belts on mine when it gets a flogging and was thinking a serpentine belt may be a good option. Its a worked alloy 250 and everything is allighned and new not a fault with parts it just throws them off. Engine balanced and new balancer. cant be bothered with modiying and lowereing alternator and putting idler pulley ect on. Its in cortina with twin thermos on alloy radiator that only just clear water pump pulley either side. any ideas or info

The pulleys aren't lined up properly or else it wouldn't throw belts.
I had the exact same issue with my old crossflow,anything past 5000rpm and it ate belts,i could never get the alt lined up properly... just lived with it.
The alternator bracket has too much play in the bolt holes so its near impossible to get lined up.
Correctly aligned pulleys with the correct v section belt don't throw belts.
If I had my time again id have just used an e series 4.0 sohc with a carby... heaps easier to make power with.