New Product Requests

[joe_db]

What have you?
What I could really use right now is a bracket to drive an alternator from the crank. I am twoblocked at the 50-60 amp point and want more.

[Dave Neptune]

Joe, I think any way you do it will require some cobbling. I don't think a true "CRANK DRIVEN" set up would give you the required RPM's for good charging and cooling of the alt. Perhaps using the flywheel mount for the fresh water pump set up could be modified as various pulley sizes are readily available.
It may be easier to modify the accy drive and alt pulley to something more robust or even a cog belt set up. Lots of stuff available from McMaster Carr or Boston Gear and I'm sure the accy drive pulley is a std pulley diameter and mount. There are also many "tapered expandable" mounts for many bore diameters and they drive well absorbing lots of power and run quite true.

I have moved various engine accy's on hot rods and boats using readily available pulleys and spacers to clear whatever is needed when changing engines to something else entirely.

Dave Neptune

[joe_db]

Joe, I think any way you do it will require some cobbling. I don't think a true "CRANK DRIVEN" set up would give you the required RPM's for good charging and cooling of the alt. Perhaps using the flywheel mount for the fresh water pump set up could be modified as various pulley sizes are readily available.
It may be easier to modify the accy drive and alt pulley to something more robust or even a cog belt set up. Lots of stuff available from McMaster Carr or Boston Gear and I'm sure the accy drive pulley is a std pulley diameter and mount. There are also many "tapered expandable" mounts for many bore diameters and they drive well absorbing lots of power and run quite true.

I have moved various engine accy's on hot rods and boats using readily available pulleys and spacers to clear whatever is needed when changing engines to something else entirely.

Dave Neptune

I guess I wasn't clear, I meant a belt drive, not actually direct off the crank. The accessory pulley is not going to get much bigger without hitting the engine, a larger pulley will have to be off the front.

[Dave Neptune]

If I remember correctly Hanley did just that to charge at lower RPM's. There is probably a picture on one of his posts. It did look like a nice job done.

The nice thing about a cog belt or a serpentine drive is far less slip for the same tension. That reduces bearing loads and belt temps for a far longer life.

NOTE with a cog or serpentine drive on the accy drive will yield a much larger drive diameter and finding a smaller one for the alt should be no problem all you would need to adapt is the alt fan which could be easily mounted with a few machine screws to an aluminum pulley. Aligning for center is not hard to do, done it many times on other things building custom machinery, dust guards , oil slings and other drive items.

Dave Neptune

[hanleyclifford]

If I remember correctly Hanley did just that to charge at lower RPM's. There is probably a picture on one of his posts. It did look like a nice job done.

The nice thing about a cog belt or a serpentine drive is far less slip for the same tension. That reduces bearing loads and belt temps for a far longer life.

NOTE with a cog or serpentine drive on the accy drive will yield a much larger drive diameter and finding a smaller one for the alt should be no problem all you would need to adapt is the alt fan which could be easily mounted with a few machine screws to an aluminum pulley. Aligning for center is not hard to do, done it many times on other things building custom machinery, dust guards , oil slings and other drive items.

Dave Neptune

I do run the alternator off the crank using dual belts. I have crank pulleys for 2:1 and 3:1. It is necessary to cobble a bracket and good to get the Dutton device for tensioning.

[hanleyclifford]

What have you?
What I could really use right now is a bracket to drive an alternator from the crank. I am twoblocked at the 50-60 amp point and want more.

One of the less than desirable features of the Atomic 4 is the accessory drive of the alternator. Back in the day of meager electronics the small alternators were ok but even then low rpms were not good for the alternatrors. Alternators like to run at high speeds, especially big ones with internal fans like the Balmars. The accessory drive should be reserved for one of your water pumps and the alternator should go to a new bracket on the cylinder head. I found that the 3:1 was a bit much and scaled back to the 2:1.

[hanleyclifford]

https://www.moyermarineforum.com/for...1&d=1699322739 3:1 sheaves

[joe_db]

That is exactly what I want

[edwardc]

Keep in mind that the A4 only has, at most, 30HP to work with. Use too big an alternator and you risk turning the A4 into a 30HP genset with insufficient power left for propulsion!

[hanleyclifford]

Keep in mind that the A4 only has, at most, 30HP to work with. Use too big an alternator and you risk turning the A4 into a 30HP genset with insufficient power left for propulsion!

That is exactly why I went to the the 2:1 arrangement. I think at one point we decided that every 25 amps costs 1 hp. Seldom do we get to the 30 hp potential. Most of us don't get beyond 15-20 hp most of the time. Ed's warning is well taken.

[hanleyclifford]

That is exactly what I want

As you can see I use the early head which makes the angle iron bracket fit nicely under the head bolts. Plan to get longer studs from MMI. As you see the picture shows the big 3:1 double sheave. I got a little greedy and had to back off.

[ndutton]

Joe, an option is to mount the alternator off of the engine on surrounding boat structure, commonly seen with refrigeration compressors. The low RPM issue can be easily handled by pulley ratio. However, the significant horsepower hit in the amperage range you're seeking will remain constant and you only have 30HP to start with (@3500RPM), more like <20HP at our normal cruising RPM. There's no free ride.

Why do you need all the amperage?

[joe_db]

Joe, an option is to mount the alternator off of the engine on surrounding boat structure, commonly seen with refrigeration compressors. The low RPM issue can be easily handled by pulley ratio. However, the significant horsepower hit in the amperage range you're seeking will remain constant and you only have 30HP to start with (@3500RPM), more like <20HP at our normal cruising RPM. There's no free ride.

Why do you need all the amperage?

Several things going on:
1. Full fielding a slow turning alternator is a worst-case situation, lots of amps in the field, slow turning cooling fan. Before I had a temp sensor I was lucky to get 3 years between shop visits, now at least it backs off when too hot, which leads to....
2. Charging at anchor means either annoyingly high RPM or not very many amps. I would really like a better ratio.
3. I have a 4D thin-plate AGM that will take a LOT of amps. It would be really nice to be putting 100 amps into it instead of 50 in an hour.
4. Future plans include a big lithium battery and electric refrigeration.
5. I have the horsepower thing covered, I can switch to small engine mode which caps the field at 50%. It actually gains me about 100-150 RPM when the alternator is going full blast and drops the charging amps from say 58 down to 18-20. This is way better than just turning the voltage down, it still hits the target voltages eventually, it just takes a lot longer.
6. I like new inventions, this is a challenge.

[hanleyclifford]

Several things going on:
1. Full fielding a slow turning alternator is a worst-case situation, lots of amps in the field, slow turning cooling fan. Before I had a temp sensor I was lucky to get 3 years between shop visits, now at least it backs off when too hot, which leads to....
2. Charging at anchor means either annoyingly high RPM or not very many amps. I would really like a better ratio.
3. I have a 4D thin-plate AGM that will take a LOT of amps. It would be really nice to be putting 100 amps into it instead of 50 in an hour.
4. Future plans include a big lithium battery and electric refrigeration.
5. I have the horsepower thing covered, I can switch to small engine mode which caps the field at 50%. It actually gains me about 100-150 RPM when the alternator is going full blast and drops the charging amps from say 58 down to 18-20. This is way better than just turning the voltage down, it still hits the target voltages eventually, it just takes a lot longer.
6. I like new inventions, this is a challenge.

And a challenge it will be. I don't think it can be done in the water unless you have a spare engine to use as a mock up. It is vitally important that the alternator axis of rotation be parallel to the crankshaft within very tight tolerances. It will be especially challenging using the late head. As you can see I use the early head even though I have a late engine. Looking forward to following your project.

[joe_db]

If I do it the way you did I'll need to dig up a junk engine to work on.
I was thinking about something like this, but designed for the bolt pattern on the front of the A4.
I can mock it up in wood first and then get it cut in metal.