This reminds me that I still need to fix mine. I've been running total loss electrics at the moment, but would have liked lights in Winter. I need to have another look to see if I can get a one wire alternator in the UK at a reasonable price. If not I was almost there with how to mount a standard A127, just not 100% happy with getting the pulley alignment correct. Trouble is whenever I think of it, I want to use the tractor so don't want to leave it in bits.
Alternator and regulator question - Siromer 304 / Jinma 254
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Hi, just in case I manage to source one, is that Delco 10SI a straight bolt-on replacement, other than sorting out the correct pulley size? It's the mechanical aspect of the A127 install that I'm not happy with rather than the electrical aspects. With the A127 I would have to add spacers to get the pulley out to the correct alignment.
Bob Rooks
Elite Member
For my application the Si alternator was a direct fit. All I had to do was buy a new belt. This is the pulley you will need: New Premium Wide Alternator pulley V 5/8"- 3/4" for Delco 10DN 10SI 12SI | eBay
Bob Rooks
Elite Member
For one thing, my alternator is a 12Si but I believe the frame dimensions are the same. My pic shows a spacer on the bottom mount, that spacer was part of the original installation. The upper mount shows a spacer washer between the ear and adjusting bracket. That was all that was required. Also, the pic shows I'm using the pulley that came with the original alternator, which didn't spin it fast enough at low rpm's. Your setup may be completely different from mine, so I can't say for sure.
Side note:
You're replacing a TEFC alternator with an open frame unit with a fan that takes cooling air from the front, which is not a problem on a car, but on a tractor a lot of dust and dirt, and chaff get thrown into it. That's why I specifically chose the 12Si unit that draws cooling air from the rear with the front closed off.
Thanks. That's a good point about cooling air which I need to check out. However we don't have any front mounted implements so no special reason to think more dust comes from the front that from the back. Our digger (backhoe your side of the pond) has an open frame A127 which hasn't suffered too much.
Bob Rooks
Elite Member
My Mitzi excavator's (digger?) engine is well isolated, and also has a 40 amp Lucas A127, and a pusher fan.
Did a trial fit today, there are a few things to sort out but we're nearly there. Things I found I had to deal with included ..
(1) The bracket that bolts onto the engine block isn't quite true, so the alternator doesn't sit completely parallel with the engine axis, putting the front of the alternator a bit further away. I've not done anything about this yet, possible filing the mounting surface do the trick. OK, not really a 10SI issue.
(2) The mounting block on the 10SI was slightly longer than the space on the mounting bracket, resolved by a bit of filing
(3) The hole was too small for the 10mm bolt, quick look showed a steel sleeve in the casting which I was able to remove
(4) Mounting and adjustment brackets on the 10SI are opposite each other, at 180 degrees, whereas the original had them around 120. This means the adjustment strap can't reach round. Relocating it to a different bolt on the pump moves it clear, but it needs to be just over an inch longer. As a temporary fit I used an off-cut of steel just to extend it. Will need to work out a proper solution once I've sorted out pulley and belt.
Aside from these glitches I need to decide on the pulley size. For the trial fit I used the pulley off the old alternator, outside diameter 85mm. As alternatives I have the one that came with the 10SI, OD=60mm and I also have a 65mm from a Lucas type alternator. I started with the largest because I don't really need the full power of a modern alternator, and I figured it was better too slow than too fast. However with the 85mm it doesn't fire up until the engine is revved up a bit. Once it's burst into life it still keeps pace with all the lights even at idle.
I also need to replace the belt, I knew it was in bad condition but didn't realise how bad. Standard belt looks like size A39, so I've ordered one of those and also an A38 to help with adjustment and/or smaller pulley.
(1) The bracket that bolts onto the engine block isn't quite true, so the alternator doesn't sit completely parallel with the engine axis, putting the front of the alternator a bit further away. I've not done anything about this yet, possible filing the mounting surface do the trick. OK, not really a 10SI issue.
(2) The mounting block on the 10SI was slightly longer than the space on the mounting bracket, resolved by a bit of filing
(3) The hole was too small for the 10mm bolt, quick look showed a steel sleeve in the casting which I was able to remove
(4) Mounting and adjustment brackets on the 10SI are opposite each other, at 180 degrees, whereas the original had them around 120. This means the adjustment strap can't reach round. Relocating it to a different bolt on the pump moves it clear, but it needs to be just over an inch longer. As a temporary fit I used an off-cut of steel just to extend it. Will need to work out a proper solution once I've sorted out pulley and belt.
Aside from these glitches I need to decide on the pulley size. For the trial fit I used the pulley off the old alternator, outside diameter 85mm. As alternatives I have the one that came with the 10SI, OD=60mm and I also have a 65mm from a Lucas type alternator. I started with the largest because I don't really need the full power of a modern alternator, and I figured it was better too slow than too fast. However with the 85mm it doesn't fire up until the engine is revved up a bit. Once it's burst into life it still keeps pace with all the lights even at idle.
I also need to replace the belt, I knew it was in bad condition but didn't realise how bad. Standard belt looks like size A39, so I've ordered one of those and also an A38 to help with adjustment and/or smaller pulley.
Re-checking I was miles out with the pulley size. The crankshaft pulley is actually only around 130mm diameter, so even with 60mm on the alternator it's bit slower than ideal. However I think it'll have enough output for what I need. It still needs a blip of throttle to get the alternator to kick in. This is visible by the ammeter needle flicking. Once the alternator's active it keeps on charging right down to idle, and at idle it can keep up with all the lights and still put a few amps into the battery. Ironically I might end up fitting a charge warning light.
Mechanically it's not so good. I can tidy the tension adjuster which is a bit of a lash up at the moment. But I had to put more spacers than I'd have liked behind the pulley so now I can't fit the lock washer. I think if I was doing this again I'd use a Lucas alternator. I'd have to make a mount for it but in doing so I could get it mounted exactly right.
Current tensioner lash-up. Arrow points to the bolt where it's supposed to fit, but as you can see this doesn't clear.
Mechanically it's not so good. I can tidy the tension adjuster which is a bit of a lash up at the moment. But I had to put more spacers than I'd have liked behind the pulley so now I can't fit the lock washer. I think if I was doing this again I'd use a Lucas alternator. I'd have to make a mount for it but in doing so I could get it mounted exactly right.
Current tensioner lash-up. Arrow points to the bolt where it's supposed to fit, but as you can see this doesn't clear.
