Alternator Rotation Direction

[GregH]

Direct drive A4. Flywheel end I'm designating as "front"...

When standing at the "front" looking at the alternator, which direction do the aux drive and alt pulley spin? Counter-Clockwise?

[thatch]

The short and "long, long, long answer"

The short answer is yes, the alternator does turn in the same direction as the flywheel. Now for the long answer. Recently, while mocking up an engine for another application I found that, because of space limitations, mounting the alternator backwards, would work out much better. After a little "net searching" I found that most alternators will generate just fine while spinning in either direction. The major drawback with doing this is that the cooling fins on most automotive alternators are orientated to pull the cooling air while spinning in one direction only. However, there are some alternators, like the Moyer 55 amp unit that have "omni-directional" cooling fans that will circulate air regardless of the direction it's spinning. One piece of automotive trivia I found, was that the 1960's Corvairs actually had a special "reverse" alternator fan plate that was needed because it's very unusual mounting design requiring reverse rotation. I wound up using a spare 55 amp Moyer unit which solved my design challenge. Sorry for the long winded answer, but hopefully, some will find it as interesting as I did.
Tom

[GregH]

I was looking at possible Balmar replacement for the rebuild and they made reference to rotation direction.

It was very helpful and confirming thanks!

[romantic comedy]

About 22 years ago I bought a 100 amp Blamer alternator. I mounted it on a bulkhead driven off the crank. This position is "reverse rotation". Balmer sold me an omni directional fan. They included a drill bit and complete instructions.
The standard fan has curved blades for rotation in one direction. The omni fan has straight blades. I have included pictures of the fan and the alternator mounting. It uses a 1/2 inch belt. It is still there and has worked well.

[Al Schober]

At one time, had a 37' trawler with twin Perkins 6-354s. Rotation was opposite on the 2 engines. Alternators had different fan blades as well as the two water pumps being piped differently - IN on one was OUT on the other.

[tenders]

I'm surprised you can mount an alternator on the bulkhead. That doesn't cause misalignment, or slippage, or squealing as the engine bounces around on the mounts and the hull flexes? Maybe a little belt wear is not enough to care about.

[edwardc]

Somewhere back in time, there is an excellent series of posts by hanley on the flywheel-end alternator mount he built onto the head, as well as a series of experiments on belt and pulley sizes.

[romantic comedy]

I'm surprised you can mount an alternator on the bulkhead. That doesn't cause misalignment, or slippage, or squealing as the engine bounces around on the mounts and the hull flexes? Maybe a little belt wear is not enough to care about.

It has worked well. My engine is rigid mounted so there is minimal flex there. Hard to say how much the hull flexes but I have had no issues. The belt wears minimally. I was a bit concerned about the side load causing the engine to move out of alignment, I fabricated a simple screw type thingy that went from the engine to the bulkhead, to counteract that pull. I never installed it and have not had any alignment issues. In my youth I saw many fishing boats that had a bulkhead mounted water pump, I figured I would give it a try.

I remember Hanley's (Hanley Clifford, I think) mount on the starboard side of the engine. It would probably show up on a search. I am sure that mount would work well. I think Hanley ran a pulley ratio of 3:1 which would allow more cooling then the ratio I am using.