Need help with screeching belts that just will not stop.

I'm running two belts with duel pulley on the alternator (no air pump) and thought that the screeching should have stopped since this doubles the contact area on the water pump. It got better with two belts but still drives me nuts.

I'm assuming that the slippage is occurring at the water pump.

Is this happening to anyone else that has the duel pulley setup? I thought the duel belts would have solved this problem.

I want to hear the engine not the screeching belts!

 

Is your water pump or alternator seizing up?

Make sure the belt surfaces of the pulleys are absolutely clean and smooth.

Did you tension the belts so you have about 3/4 of freeplay on the longest side?

 

Try cleaning the pulley up with some sandpaper..
and get 2 new belts.
I had put on a dual pulley system once,and one of the belts was "longer"..even though they were both the same part number.(one worn and stretched more I guess).
I put on 2 new ones and it was fine.
I now have a Gilmer belt drive(one Huge belt).

 

It's fixed, no more screeching belts!

First I cleaned the pulleys with sandpaper until they were absolutely clean and smooth. Although the water pump pulley appeared to be clean, once I started to sand some rust appeared which cleaned off completely with some fine sandpaper.

I originally had about 1" play in the belts. Got a pry bar under the alternator and tightened the belts down to 3/4". The test drive confirmed that the problem was fixed, going up to 7000+ rpms and absolutely no screeching belts.

Thank you both for your help. Now I can get on with the restoration and know that at least one small but irritating problem has been fixed.