I've been doing a lot of research on these, and I'm sure there are people who are MUCH more knowledgeable about this than myself on here. So I figured I would pick your brains...

What we (I) know:
-It is common to have belt squeal on a 3g swap if using the 130A alternator
-To eliminate said squeal, we have a few options: 1) tighten the vbelt up to a ridiculous tension, but it can be hard on equipment and does not provide guaranteed success. Or 2) swap to a double belt alternator pulley, which would also (for me) send me on a hunt for a water pump pulley with an extra groove.
-To reduce or eliminate belt squeal, we are essentially trying to increase surface area contact of the belt to the pulley.

What I don't know:

I found a larger diameter alternator pulley- part number: SUM-3969 Summit racing deep groove alternator pulley.

Link to part: https://www.summitracing.com/parts/sum-g3969/overview

With a larger diameter pulley, we would be enhancing the contact between the belt and the pulley. However, we would also be slowing the rotation of the alternator. The pro I see with slowing down the alternator would be (maybe) increased life of the alternator due to less wear and tear. The quite obvious con would be that we are limiting the production of the alternator. I need help determining how much less power a 130A alternator would produce running that larger diameter pulley vs. the standard smaller pulley. Do any of you think that there could be unintended consequences of running the alternator at a slower speed, like overheating issues due to slower fan speeds? I picked up the appropriate 130A alt at a junkyard, and I want to eliminate the squeal IF it's reasonable.

Also, it's very possible that I have absolutely zero idea what I am talking about... if that's the case, please do fill me in

 

compare the circumference of the current pulley to the 5" diameter pulley...unless you have enough electrical accessories that use the majority of the 130 amps, I doubt you'll notice a difference in output since the output isn't directly proportional to the rpm...this link may help
https://balmar.net/balmar-technology...output-curves/

If you go with the deep groove pulley, make sure to use the correct width belt. you never want the v-belt to bottom out in the pulley, it should only contact the sides of the v...

 

I did the 3g swap about 3 years ago. With a fresh belt...little to no squeal. As the belt started to get seasoned...it would squeal on start up and then over time if I mashed them gas pedal hard....it would squeal.

I tried finding a dual belt pulley set up and just couldn’t find all the correct pulleys to make it go.

I found a thread on the 460 forum where a guy modified his crank pulley to a micro groove pulley for the alternator and attached the front part of the two groove set up (from the original 3 groove pulley). The micro groove pulley belt set up bites much better and doesn’t slip like the v belt.

So I converted a lower pulley set up to the hybrid micro groove for the alternator and the double groove front for the power steering and water pump belt. Seems to work pretty good. No belt squeal so far. I did it this past winter. Did a write up on it with pictures as well. My engine is a 460.

Later, SB4x4

 

Do you have a picture of the modification? For the micro groove pulley, did you just use the crank pulley from the donor vehicle, or did you have to buy a single pulley for it?

 

https://www.ford-trucks.com/forums/1...y-upgrade.html

 

Redroad beat me too it. I was gonna add the link but had to get out the door and on the way to work.

Thanks Redroad!

 

No problem. Enjoyed reading the thread. Great work.

 

Saw this on another website talking about belt squeal with the 3G alternator. They said there is a soft start voltage regulator that ramps up instead of dumping all at once. The motorcraft even called it a soft start part# GR814 but that has been superseded to GR822 and it does not say soft start. But there is one on US Auto Electrics R14030 that says it replaces the GR814. Just thought I would put this out there in case it could help someone.

The pulley you did is great.

 

My F350 originally came with the larger diameter of the two common Ford alternator pulleys and never squealed. The same alternator type on my Bronco with the regular size (more common at least in my experience) squealed like a stuck pig any chance it got. That one was on a 302 so was easy (relatively speaking that is) to find the proper dual-groove pulleys and that worked just fine. My 400 has those oddly sized pulleys that won't allow me to use a dual-groove pulley on the alternator, but luckily it never gave me any trouble.
I'll get a measurement just as a comparison, but i don't think it's a full 5" diameter. It is however a slightly deeper groove than the smaller one too.

As was said, I would not worry too much about using a larger pulley on a 3G (or even a large-case 1G) because they can put out gobs of power even at lower rpm levels.

Good luck. Hate that squealing sound!

Paul