Vee belt problems

[solarman216]

Anyone on here expert on Vee belts, I am having problems with my air compressor, I think I know the problem but do not know how to cure it other than put an idler pulley on the slack side, so here it is, 12 HP 4 stroke motor driving a large horizontally opposed twin compressor, (do not know its CFM but it was made to drive a road drill with only the tubular frame as a receiver, petrol driven with twin belts, engine blew up (might have been twin but cannot remember, it was many years ago) so I grabbed it) so my motor being single cyl 4 stroke the power kick is high, couple that with the twin pulses from the compressor and you can begin to see why the slack side of the belts start to jump wildly near full load, just fitted a matched pair of Gates A belts but no better, if I continue to run it as is the belts will fail in no time, so you see the problem, maybe they make stronger non stretch belts but I have no idea, Rick