1-wired alternator and V-belt squeal

[chris401]

Dual alternator pulleys started in FE powered 1965 on pickups. I do not know about the Y-Block era. It is mentioned on the Slick60's website what the circumstances were to get the dual alternator belt set up. Seems like it was F-100 with a towing package and all FE F-250s. The better vanilla dual belt set up came out in 68 with the new balancer. Pictured is my 65 F-250 and a 66 F-250 engine. 

EDIT: The 3G I swapped in is a Ford unit. I did it when the truck got a new wiring harness. Simply ran the exciter wire through the ALT bulb. Works as it should but does squeal at first start if it sits for a few days with the trailer plugged in.

[cleandan]

V-Belts run on a few principles.
Look at the side view of a V-belt.
The cord body you see is where the power is transfered.
The rubber V below the cord body is there to keep the belt from being forced inot the pulley groove.
The rubber above the cord body is there to give substance and stability to the cord body.

V-Belts squeal because they are slipping...I know. EVERYBODY knows that.
But did you know the slip can come from worn pulleys, worn belts, dry belts, overheated belts, wrong sized belt for the pulley groove depth and groove angle, improper tension, belt whip, contamination in the air or directly on the belt.

The belt size, and pulley diameter/contact area play a big role in the amount of power a belt can transfer.

With your one wire alternator keep in mind it was probably designed for use with a poly-V Belt rather than a single V-Belt.
The poly-V Belt is capable of transfering much more torque than a single V-Belt and often poly-V pulley is designed smaller in diameter too. This often results in a smallish single V pulley being installed on the alternator in order to keep the same speed as the original intended use...and this often does not correlate to a good fit with the FE installation.

Worn pulleys get a bulge cut into them where the cord body of the V-Belt rides. Once this worn area is deep enough (does not look like much wear) the new V-Belt can not transfer proper torque because the cord body is not in proper contact with the pulley.
The belt will slip, squeal, and wear quickly but then a new issue pops up.
The belt is no longer a linear sided V-belt. Instead it now has a weird bulge shape to match the pulley and this never allows for full power transfer...It also causes other issues.

If the pulley has the correct depth and angle, and is not worn.
If the belt is the correct size (V shape, angle and depth) and riding at the correct depth in the pulley. (the V-Belt should be almost flush with the top of the pulley, or slightly recessed in the pulley, not sticking up any amount above the pulley.)
If the contact area around the pulley is maximized for the application and location and you still get belt slip...Then you need to change to more pulleys in order to transfer the required power.

[allrightmike]

Very good post cleandan; you mention contact area, could that be called wrap or how many degrees of belt contact does exist? I have seen installations where the belt almost just passes accost the pulley.

[cleandan]

allrightmike, that is exactly what I am talking about. The amount of belt contact around the pulley has a huge impact on the power that belt can put into the pulley.
There are other factors used to determine which belt is best: how much wrap, the diameter of the pulley, the physical size of the belt, and the belts speed, among a few other things.

But, basically, if you get more belt to pulley contace, you increase power transfer.

Yes, I have seen some belt to pulley applications with about 30 degrees of belt wrap, basically the belt is passing by the pulley. But if the pulley being driven does not require much power it will work great.

[machoneman]

Adding an idler with tension (ala' Ford's single-belt, Fox-bodied 5.0's) would help a lot with 'wrap' although it would not look anywhere near stock.

[57 lima bean]

         Not having an AMP/Volt gauge,the sound of a belt sequel is an audible prove-out.

[cleandan]

With a V-Belt, the tensioner does not work well like it does with a poly-V belt.
If you use a tensioner with V-Belts you should run the pulley on the V side of the belt.
If you run the tensioner on the back side of a V-Belt it tends to break the back of the belt and they wear out pretty quickly.

Running the tensioner on the back side of the belt will allow you to force the belt to wrap around the pulley more...with a longer belt of course, but it is not the best way to do things with V-Belts.

This is but one of the reasons the makers went away from single V-Belts.
The Poly-V Belts are capable of transfering more torque in a smaller area and being wrapped around the pulley more with less issues.

[70tp]

Maybe try a “cloth covered” lawnmower style belt?   They can tolerate some more slip without a lot of wear.   They aren’t always available in every width but usually you can get “close enough”    Lawnmower belts can transfer a lot of abuse and still not complain.   Some are available in Kevlar also.     They will tolerate  more misalignment and abuse than a normal belt. 

[BigBlueIron]

With a V-Belt, the tensioner does not work well like it does with a poly-V belt.
If you use a tensioner with V-Belts you should run the pulley on the V side of the belt.
If you run the tensioner on the back side of a V-Belt it tends to break the back of the belt and they wear out pretty quickly.

Running the tensioner on the back side of the belt will allow you to force the belt to wrap around the pulley more...with a longer belt of course, but it is not the best way to do things with V-Belts.

This is but one of the reasons the makers went away from single V-Belts.
The Poly-V Belts are capable of transfering more torque in a smaller area and being wrapped around the pulley more with less issues.

Right on the money, you can get away with it in most cases but it directly effects belt life.

If the regular dual belts are slipping try a notched or cogged belt.

Side note that has nothing to do with the performance but I have always liked the look of the dual alternator belt setup over a single for some reason. Just more industrial makes me feel warm and fuzzy.