Thinking about a serpentine belt conversion

[rslifkin]

You should be running industrial V belts. Sometimes they are called green stripe belts. They are much stronger and last longer.
I had a double V bely pulley mounted to the front pulley for a hydraulic thruster. It used a matched pair of industrial belts. The pair lasted 10 years and was fine when I sold the boat last summer.
I too question the serpentine system without a tensioner. Maybe it works fine, I would just question that.
Best of luck however you decide.

One catch to that. The Gates Green Stripe belts don't come in anything smaller than 1/2" width. If an engine uses 3/8" or 10mm belts (like mine), you're stuck with the standard grade belts (but buy good ones like Gates, Continental, etc.)

 

[C lectric]

I am going to throw in another way to think about. Of course there won't be a "KIT" but there are so many parts available that depending upon what you finally decide you want it may be the best.

A timing belt drive. Pulleys are available in all kinds of sizes and bores. The belts are available in many different widths and sizes.
One thing though is the cogs are available in different pitches so mix and match must be watched.
THese things do NOT depend on friction for the drive. The inside of the belt is cross bars or cogs that mesh with the pulleys.. All they need is to be lined up properly and snugged. The tension is simply enough to keep them in play.

Yes, it would take some investigation but MAY be worth the effort especially if you nix the serpentine belt kit.

THey are industrial drives and would be found through bearing and industrial drive shops.

If you consider going this kind of a route then be sure you always carry a spare. You won't find these at every corner yard or shop.

If I have simply complicated things then throw my suggestion out.

 

[catalinajack]

Here is a photo of one of my Lehman 120s with double belts. A serpentine kit would not work because of the pump mounted to the crank pulley. A serpentine kit includes a pulley that bolts to the existing crank pulley. No can do with that pump there. Instead, I purchased the water pump pulley and the FL120-specific Balmar alternator pulley. Everything lined up quite nicely. The belts are Gates Green Stripe 1/2`inch. I suspect, based on others' experience related here that thi pair of belts will last many years.

For anyone with a FL120 who is considering this modification know that the large water pump hose, where it attaches to the engine underneath the header tank, is too short to provide enough clearance for two belts. I had to extend the hose with a short length coupled to the main hose. Not a big deal.

 

[rslifkin]

Here is a photo of one of my Lehman 120s with double belts. A serpentine kit would not work because of the pump mounted to the crank pulley. A serpentine kit includes a pulley that bolts to the existing crank pulley. No can do with that pump there. Instead, I purchased the water pump pulley and the FL120-specific Balmar alternator pulley. Everything lined up quite nicely. The belts are Gates Green Stripe 1/2`inch. I suspect, based on others' experience related here that thi pair of belts will last many years.

For anyone with a FL120 who is considering this modification know that the large water pump hose, where it attaches to the engine underneath the header tank, is too short to provide enough clearance for two belts. I had to extend the hose with a short length coupled to the main hose. Not a big deal.

Looking at your pictures, it looks like those belts sit nicely in the crank pulley, but they look a bit too big for the water pump pulley (which looks more like it's meant for a 3/8" belt). No issues with slippage or anything with them sitting like that?

On my engines, the crank pulleys nicely accept 3/8" or 1/2" belts, but the water pumps and alternator only seem meant to accept 3/8" belts. The 1/2" ones sit very high out of the pulley like what you're showing (but slightly worse), so I didn't use the 1/2" belts at my last replacement.

 

[SteveK]

I have a 2 foot metal ruler straight edge that I lay on the alternator pulley face to span over to the crankshaft pulley. The crankshaft pulley is the standard to align all other pulleys to. You have to eyeball it some but you can get close enough to see if you have a real problem. Now there are laser alignment tools available. You might be able to borrow or rent one from an auto parts store. I'm trying to find a decent youtube video. The pic below shows a laser setup but a straight edge works the same except I use the pulley face with a v-belt.

Figure 4 offset is usual occurance with a new alt install.
Figure 5 seems like a one in a million possibility with alt not aligned. neither should be the water pump pulley, correct?

 

[AKDoug]

Figure #5 can happen when the tensioning flange isn't properly aligned with the cylinder block, a washer or a bushing can push the pulley into alignment. The alternator can be allowed to offset just enough to cause the belt dust if that tensioner isn't also aligned properly. I think this is more likely with a single foot alternator.

 

[catalinajack]

No issues. Yes, they do sit a bit proud. A standard non-Green Stripe 1/2 inch belt does not. Have no idea why. Definitely not a 3/8 inch pulley.

Looking at your pictures, it looks like those belts sit nicely in the crank pulley, but they look a bit too big for the water pump pulley (which looks more like it's meant for a 3/8" belt). No issues with slippage or anything with them sitting like that?

On my engines, the crank pulleys nicely accept 3/8" or 1/2" belts, but the water pumps and alternator only seem meant to accept 3/8" belts. The 1/2" ones sit very high out of the pulley like what you're showing (but slightly worse), so I didn't use the 1/2" belts at my last replacement.

 

[FF]

Sometimes there is enough room to wire tie a spare belt or two inboard of the working belt.


When the working belt dies its cut off and usually the alt only needs to be loosened and re tightened to be back underway.

 

[Bendit]

I had pre-installed belts, held in place with cable ties, for both the main alternator and the power steering pump. Unfortunately, when I came to use them, they had perished (delaminated) due to engine heat i assume. So their life wasn't much different to those in use.

 

[DDW]

The degrees of wrap on the belt is critical to slippage. If the micro V belt kit doesn't include idlers or whatever is necessary to get a lot of wrap it won't work any better. A micro V that wraps 180 deg will transmit a lot of power without slipping. That is the reason on a car they make sure that it is "serpentine".

 

[cardude01]

Thanks for all the ideas. I’ll get down to the boat in Florida mid april hopefully to do some measurements.