Dual groove pulley for new alternator

[707Bronk]

If its a squeal problem, a slightly larger single groove pulley and a turnbuckle style tensioner like below did the trick for me. I was able to eliminate the squeal with just the tensioner alone but the belt was too tight for my liking.

https://www.ebay.com/itm/262718901558

 

[Rustytruck]

I had a problem running the stock ford 2 groove pulley from my 1974 with smog pump. I was trying to use the small case 90 amp areostar alternator.

you have to run a spacer washer for the pulley to clear the case. then when you put the pulley on there was almost no threads to clear the case. so i had to find another path.

chevy had a factory 2 groove pulley that fits perfect the face counter bore is deeper allowing a lock washer and nut.

https://classicbroncos.com/forums/showthread.php?t=282842&highlight=chevy+alternator+groove+pulley

 

[jerry]

Not to keep resurrecting an old thread... But I need a "sanity check". I think the issue is pretty obvious (even moreso as I type this), but someone may bring up an issue I'm missing.

Picked up a two groove pulley. Installed it, then eyeballed it a little more closely (see attached). The grooves are different sizes / diameters. To me this appears more like a pulley you'd place on the end of a motor to drive either two different sized belts, or to allow for an (albeit slight) RPM change by switching a single belt between pulleys.

If it was driven by two identically sized belts off the crank... Then it's not going to work.

Thanks for your help!

 

[Rustytruck]

when i have seen that type of pulley used its usually used the thinner belt to Drive the fan and smog pump and the wider belt to drive the power steering pump or AC air compressor. of course you have to have wide belt pulleys in all locations.

 

[jerry]

RustyTruck,

I checked with the vendor that I purchased it from... And he essentially said the same thing, showing a couple of crank pulleys that were set up for different size v belts.

I assumed that most setups were like mine with identically sized belts... But I can see where they might differ with good reason.

Thanks for the input.

 

[jamesroney]

Not to keep resurrecting an old thread... But I need a "sanity check". I think the issue is pretty obvious (even moreso as I type this), but someone may bring up an issue I'm missing.

Picked up a two groove pulley. Installed it, then eyeballed it a little more closely (see attached). The grooves are different sizes / diameters. To me this appears more like a pulley you'd place on the end of a motor to drive either two different sized belts, or to allow for an (albeit slight) RPM change by switching a single belt between pulleys.

If it was driven by two identically sized belts off the crank... Then it's not going to work.

Thanks for your help!

Where in the world did you find the 1984 F250 6.9l IDI alternator pulley?

It has no use on an Early Bronco. The alternator on the 6.9 drives the vacuum pump with a narrow belt. The speed of the vacuum pump is independent to any other accessory. The 6.9 uses a heavy duty 17/32 wide belt for the alternator.

You need to find an alternator pulley with identical grooves if you want to run a dual belt. The pulley you have cannot be run with dual belts. The smaller groove has a smaller diametral distance. (And therefore runs “slower” than the wide belt.)

Find an alternator pulley from a 1965+ Ford 390 with dual belt alt.

 

[jerry]

Where in the world did you find the 1984 F250 6.9l IDI alternator pulley?

<SNIP>

Find an alternator pulley from a 1965+ Ford 390 with dual belt alt.

It was an honest mistake from the vendor. I slso take partial responsibilty for not better communicating how my truck was set up.

 

[m_m70]

Well I'll chime in and may not be the best solution but worked for me....
I went with a three groove crank pulley and running two on the alt, water pump and crank and the third just to the crank and power steering. Note I'm using an electric fan as well. Also, had to add spacers (ace hardware) to bump power steering bracket out. even with this, I've had squeal but switching to "top cog" belts have helped.

 

[jerry]

Well I'll chime in and may not be the best solution but worked for me....

I appreciate the input and pics - thank you!

While not directly related, I did stumble across this motortrend article which was interesting:

https://www.motortrend.com/how-to/install-high-output-ford-3g-alternator-older-fords/amp/

I also have another question - should I run a separate ground from the back of the alternator case to the engine block, or are the mouting bolts sufficient? Also - is there a separate ground to the body - if so, where would that be located?

 

[Rustytruck]

I ran the separate ground from the alternator case to the engine block ground where the battery negative bolts to the block. this has to be a large ground wire even though it is redundant.

 

[jerry]

I ran the separate ground from the alternator case to the engine block ground where the battery negative bolts to the block. this has to be a large ground wire even though it is redundant.

Seemed like a good idea, and simple enough to do. Thanks!

 

[gr8scott]

I ran the separate ground from the alternator case to the engine block ground where the battery negative bolts to the block. this has to be a large ground wire even though it is redundant.

I did the exact same thing.

 

[DirtDonk]

Yep, done many times and certainly does not hurt!
Yes, the alternator will ground to the engine through the bolts AND the case itself where it touches the engine block/cylinder head/mounting bracket.
However, with paint, rust, differing materials, over the years this ground path may not be all it's cracked up to be. At least that's my feeling every time I talk myself into adding one of my own.
Ford did not have a separate ground that I'm aware of, but that has not stopped me yet.

You do not need one to the body like the original had, because that was actually a ground connection to the voltage regulator mounted to the body. Not the body necessarily, but the regulator itself was being bonded to the alternator in those old cases. The internal regulator is already attached to the alternator, so if it has a grounding connection it's handled through the mounting points inside.
But hey, I'm guessing it probably would not be the end of the world if you'd added one anyway!

Paul

 

[sprdv1]

Yep, done many times and certainly does not hurt!
Yes, the alternator will ground to the engine through the bolts AND the case itself where it touches the engine block/cylinder head/mounting bracket.
However, with paint, rust, differing materials, over the years this ground path may not be all it's cracked up to be. At least that's my feeling every time I talk myself into adding one of my own.
Ford did not have a separate ground that I'm aware of, but that has not stopped me yet.

You do not need one to the body like the original had, because that was actually a ground connection to the voltage regulator mounted to the body. Not the body necessarily, but the regulator itself was being bonded to the alternator in those old cases. The internal regulator is already attached to the alternator, so if it has a grounding connection it's handled through the mounting points inside.
But hey, I'm guessing it probably would not be the end of the world if you'd added one anyway!

For sure....