I'M HAVING PROBLEM KEEPING PULLEYS BELT ON MY 406 SMALL BLOCK CHEVY MOTOR.I HAVE A BIG ALT PULLEY AND STOCK PULLEY ON WATER PUMP PULLEY AND CRANKSHAFT PULLEY,WHICH IS 8INCH WIDE.SOMEONE TOLD ME IF I CHANGE THE TWO STOCK PULLEY WITH THE MARCH PULLEY.I WOULD HAVE HEATING PROBLEM.BECAUSE THE MARCH PULLEY ARE SMALLER.I NEED HELP.

You didn't say at what rpm you are loosing the belt. If it's at high rpm and you have the pulleys aligned perfectly, then slow em down.

Do you have the deep groove high performance GM pulleys on the car?

There was a discussion in this months Chevy High Performance. Apparently, a lot of belt throwing can be traced to cheap replacement water pumps. When they are built/rebuilt, the manufacturer does not correctly place the pully mount on the shaft, resulting in belt misalignment. They showed two pumps and the difference between the pulley mount placement was almost 1/4 inch.

This might be a place to start.

New belt? Belts stretch and flop, then come off when they get some age on them. Or misalignment could cause this. Pulleys run smooth, no wobble?

If you get new pullys, I would suggest getting the march serpintine converstion deal, I'm running it on my camaro and haven't had a problem and they look cool too.

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68 468 700R4

If your alternator mounts to the header, the bracketry could be flexing a lot. Maybe switch to a long water pump and late model brackets if your heads have holes in the front. Much more solid, and the belt is a lot shorter.

have you checked the pulley alignment ?


[This message has been edited by DOUG G (edited 02-23-2000).]

I am with Doug G. and others. It sounds like your pulleys are mis-aligned. That's where I would start first.

Hey Joe,
I had the same problem throwing belts at hi rpm (around 6500, if I recall). I did replace the lower pulley with a smaller one and replaced the belt with a narrower one. Oh, and the alignment was and is still way, way off. After 3 years, no problems and no overheating. (It runs between 160 and 170 degrees.) Good luck.