I’ve never seen a vehicle routed like that from the factory. It was common to have 2 alternator belts and water pump on medium duty trucks. Maybe replace the crank pulley with a three groove all the same diameter. Then shim out the ps pump to line up with the crank pulley and drive it directly off that.

 

It's not that uncommon a mod today with the 3G alternators and it works from others I've seen. Just hoping someone could save me the trouble of measuring and testing different lengths of belts to get it right.

 

Be sure of 3 things: All of your pulleys must be unworn, with perfectly flat sheave sides in reflection, with no waves, grooving, etc. Use a fresh belt of the correct type and width. Tension properly with a gauge to 100-115 pounds tension (Gates number; Ford says 110-140 for a new belt).

There are several belt company guides on how to measure belt length. If your belt squeals, it will quickly glaze to trash. More pulley detail here. Be sure you charge your battery first so it doesn't try to move the Earth on startup.

Use a tension gauge as other methods are proven unreliable, even for professionals. 115# is more than most 'feel' is right, but you don't want too much either. Always test belt tension at every oil change. I and others here run single-V with the 130A version, with no squealing, so check the first 3 things. Going with double-groove is fine also, but IMO you still need those first 3 things.

 

Be sure of 3 things: All of your pulleys must be unworn, with perfectly flat sheave sides in reflection, with no waves, grooving, etc. Use a fresh belt of the correct type and width. Tension properly with a gauge to 100-115 pounds tension (Gates number; Ford says 110-140 for a new belt).

There are several belt company guides on how to measure belt length. If your belt squeals, it will quickly glaze to trash. More pulley detail here. Be sure you charge your battery first so it doesn't try to move the Earth on startup.

Use a tension gauge as other methods are proven unreliable, even for professionals. 115# is more than most 'feel' is right, but you don't want too much either. Always test belt tension at every oil change. I and others here run single-V with the 130A version, with no squealing, so check the first 3 things. Going with double-groove is fine also, but IMO you still need those first 3 things.

I had all three, with the possibility of being less than 110# on the tension. The alternator pully was getting hot while all the other pullys were cool. I could literally see the alternator pully struggling when the lights came on or there was some load on the alternator. I simply don't have enough torque being applied to the alternator.

 

Have you had a amp load test done or in general a full functions test with idle load and rpm load? Loaded and not loaded. Why did you change alts to begin with. A 3G upgrade is a upgrade did you find you where having trouble to begin with. Just food for thought.

 

Change the alt pulley to a HiPo/Boss 302 one and it should take care of the problem. I am not sure about earlier cars but my routing is crank>wp>ps and crank>alt.

 

Yep my configuration is the same first belt on Alt>WP>Crank, and second belt on Crank>PS unit

 

The easy start is the HiPo alternator sheave. If your alternator does not like being under driven that much you can go to a dual belt or serpentine system from CVF Racing. I have the dual belt system.

 

I have just the crank/water pump/alternator setup in my 65. I was having issues with squealing when I switched over to a 3G. I switched over to the HiPo/Boss pulley and the problem went away. I have no problems with the battery staying charged.

 

Thanks Guys - yes I now think/know the pulley is the issue on my alternator. See pic attached. The sheave on there now is a 3/8" sheave and my other pulleys Crank and PS use up to a 1/2" sheave. The crank dual sheave width isn't quite 1/2 inch but fits my PS belt which is a 1/2 belt fine. I'm swapping out the alternator sheave first with the thicker version and using a 1/2 belt to see if it solves the problem. The alternator pulley is the spot that 3/8 belt currently slips and that makes sense now. Thanks guys for the responses!

 

The suggestion to move to a slightly larger alt pulley is due to the smaller 3G pulleys being very close to the minimum radius for the correct belt. Not only does the larger pulley provide more contact surface, but the belt can conform to it better. For those stuck with a little alt pulley, the belt can be changed to a tight-radius belt, which often has scallops or 'teeth' on the inside and sometimes outside of the belt.

 

@Woodchuck

The pic you show has one alternator belt and one power steering belt. Does that power steering belt also go around the alternator? On the Medium Duty Trucks (or at least on our F600) the alternator had two sheaves, the water pump had two sheaves, and the crank had two sheaves. You went to the store and bought a matched set of belts. It was mainly for redundancy as a truck was too valuable to break down.

Jason

 

@Woodchuck

The pic you show has one alternator belt and one power steering belt. Does that power steering belt also go around the alternator? On the Medium Duty Trucks (or at least on our F600) the alternator had two sheaves, the water pump had two sheaves, and the crank had two sheaves. You went to the store and bought a matched set of belts. It was mainly for redundancy as a truck was too valuable to break down.

Jason

No. The PS belt runs only off the crank pulley.

 

@Woodchuck

got it now. The PS is from crank to pump. I didn’t realize 65-66 was that way. My 67 both alt and ps go around water pump and crank.

I did learn about the Hipo pulley. I might buy one just to have around as an option.

 

On a 65 withe ps a 3/8 belt runs the crank ,w/p, alt. a 1/2" belt runs crank p/s
the double crank pulley has two different width belt grooves. you cannot run 2 belts the same width in this crank pulley over the water pump they will be running at different speeds.
See the Bob Mannal book for pictures and widths for each year.

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