Ok, I still don't get one thing. In order to tension a belt you have to have a third pulley that can be slid outward and tightened down. If Flybye only has an alternator as a third pulley (no A/C or P/S) then how does this water pump belt run? Shouldn't the alternator have a double groove pulley assuming that there are 2 grooves on the water pump & crank pulleys? Did GM ever equip these cars with idler pulleys? I'm betting that an accessory is missing, like a smog pump perhaps.

The water pump and crank pulleys are fixed and not adjustable.

Again referencing my 350, the config is right-triangular: from crank, up to water pump, over to alternator, down to crank. Alternator is the adjustable component. This matches factory config for a no AC/no AIR engine. The alternator adjustment tensions the belt against the water pump track, a crude friction setup that induces a ton of stretch (see my earlier posts this thread)and complains on sudden increases of crank torque. (Would be a great application for Gilmer belts and pulleys!)

So do the non A/C non P/S cars only run one belt? I thought there were always 2 belts around the water pump since it is such a crucial component.

Good question. The assembly manual for 75's illustrates what could be a belt between 2nd track crank and 2nd track WP, but there appears to be no reference to it in the parts breakdown on the same page ... and certainly no adjustable component or idler.

On the PS cars, it looks like they considered traingulating the PS belt across the WP pulley at one point, but the drawing was cancelled. and the final version shows the crank-WP-alt config for the alt belt, and the crank-PS config for the PS.

Go figure

Just stunbled over the fact that some Weiand water pumps support adjustment of belt tension via slotted mounting holes.

I'm running an Edelbrock pump ... not adjustable. Factory pump apparently wasn't either.

Hello all,

Along time ago, I saw a small block Vette, 60-62 vintage that had no accessories. There were two belts, one that went water pump, crank, and generator, the other was crank to water pump. To install the crank to pump belt you had to loosen the pump pulley and then tighten the pulley with the belt in place.

Maybe this is the idea for a BB w/o accessories.

Alex