TR2/3/3A TR3A Alternator Conversion

[deadair]

I recall seeing scattered discussions on converting a TR3 to use an alternator several months back, but can't seem to find them. So, forgive me for repeating a common question.

I recently installed a SPAL cooling fan, which works great. However, it draws too much power from my generator when idling in traffic. So now I'm looking at a negative ground conversion and alternator.

What alternator would be the easiest to fit to a TR3A with a narrow belt conversion already in place? It doesn't have to be the cheapest solution, just the easiest.

 

[trrdster2000]

deadair, go too VTR.org and read all about the conversion. It's easy enough and will help a lot. We also used the heavy duty wiring harness for the head lights and WOW what an improvement. Got it from VB for $30, not a plug and play as advertised, but we did add a fuse for bright and one for dim. I was thinking about writing a tech tip on how I did it, if there is some interest.

Wayne

 

[Tr3aguy]

https://www.vtr.org/maintain/alternator/gm-tr2-3.shtml

I thnk this is the link that he is refering to...

Hope that helps

 

[Moseso]

I found the GM alternator to be such a tight squeeze into a TR3 that I opted out of that one. Nippondenso makes a significantly smaller unit that is just as easy to source, and much easier to fit into the space allotted.

 

[TR4nut]

I bought a Nippondenso unit for my 3A but as yet haven't installed it. Compared to the Delco unit I have on my TR4 it is a great compact size and I don't think it will be too difficult to install. The better part is if you are going thin belt anyway you won't need to deal with changing out to a wider pulley. I've not found a good option for a wide pulley with the compact alternator.

 

[deadair]

Thanks for the input so far. I like the idea of a compact unit. What is the model number on the Nippondenso?

 

[martx-5]

I installed the Delco 10SI unit with the narrow belt conversion in my TR3. Yes, it is a tight fit, and I had to use a slightly different size belt (NAPA 7385) then the one supplied with the conversion. I forget whether it was longer or shorter. I had to make a couple of spacers. One for the bottom bracket, and one for the the upper adjusting arm. The spacer for the bottom bracket I threaded on both ends so I wouldn't have to use an extra long swivel bolt. One coming in from the front, and one from the back. The other spacer is where the adjusting arm attaches to the water pump housing. It's 5/8" long. I put that there so the bracket would line up nicely with the front of the alternator ear. However, without modifying the 10SI at all, the belt lined up perfectly. The nice thing about the Delco unit, is that it is available anywhere for a low price.

 

[TR4nut]

For visual reference, here is the Nippondenso unit I have compared to a spare Delco:

The Denso supposedly is a 45 amp unit, it was part number AND0212 from this place:
DB Electrical

Haven't hooked it up yet, so can't tell you if it works great or is worthless at this point!

 

[TR3TR6]

I also used the Delco 10SI when I replaced the generator. I had also installed an electric fan, it discharged big time when the car was idling with the generator. I kept the positive ground system in my car. I purchased a kit for the alternator that converted it to positive ground. It was pretty easy to install. I also replaced the pulley on the alternator with one that matched the size of the one on the engine. I found the pulley at a starter-alternator repair shop. The belt I used is a Gates TR24379. Its 3/4" X 38 1/2".

 

[deadair]

I also used the Delco 10SI when I replaced the generator. I had also installed an electric fan, it discharged big time when the car was idling with the generator. I kept the positive ground system in my car. I purchased a kit for the alternator that converted it to positive ground. It was pretty easy to install. I also replaced the pulley on the alternator with one that matched the size of the one on the engine. I found the pulley at a starter-alternator repair shop. The belt I used is a Gates TR24379. Its 3/4" X 38 1/2".

Can you provide more detail on the positive ground kit? It would be great to not have to do a ground conversion.

 

[TR3TR6]

The kit is made by Jimco, Inc. The instructions say it is a W500 and is made to work with the Delco 10SI Alternator along with some other Delco alternators. Its a one wire conversion.
It's been awhile since I installed the kit, but it came with a positive ground rectifier. The instructions were pretty good. One thing that you need to be aware of is that this setup draws 80 milliamps of current continuously, so if you don't drive your car for long periods, it will drain the battery. I installed a battery cut-off on mind and that took care of that issue. The Delco 10SI works really well. It's charging at idle no matter what is turned on.

 

[deadair]

The kit is made by Jimco, Inc. The instructions say it is a W500 and is made to work with the Delco 10SI Alternator along with some other Delco alternators. Its a one wire conversion.
It's been awhile since I installed the kit, but it came with a positive ground rectifier. The instructions were pretty good. One thing that you need to be aware of is that this setup draws 80 milliamps of current continuously, so if you don't drive your car for long periods, it will drain the battery. I installed a battery cut-off on mind and that took care of that issue. The Delco 10SI works really well. It's charging at idle no matter what is turned on.

Are you saying that the rectifier draws 80 milliamps? I found some off-the-shelf Delco Positive Ground Alternators (here too). Does anyone know if these have the same current draw problems?

 

[TR3TR6]

I don't know about any other ones, the instructions that came with mine said it had the 80 milli amp draw.

 

[Moseso]

I think all integral-voltage-regulator alts draw a little something at all times. I can't remember what my Denso draws, but I measured it and calculated that it would be many months before my battery was even 1/4 gone.

The battery cutoff connector was only $3.95 or something. I only use it when I put it away for the winter -- or, what it's really handy for -- when I work on the car's electricals.

I found the Denso model number thing to be a totally unsolvable puzzle. So what I did was go to the independent auto-electric specialist (he rebuilds 'em there) and asked him for the "littlest bittiest" Denso alt he had. He went right to the shelf and pulled down the perfect unit. 50 amp. Fits the car. It had a flat-belt pulley on it, but when you're dealing with the fix-it guy, instead of a parts salesman, that's no problem. It took him a whole 25 seconds to swap it out for a v-belt pulley for me -- no extra charge.

 

[deadair]

I found the Denso model number thing to be a totally unsolvable puzzle. So what I did was go to the independent auto-electric specialist (he rebuilds 'em there) and asked him for the "littlest bittiest" Denso alt he had. He went right to the shelf and pulled down the perfect unit. 50 amp. Fits the car.

Thanks, Moseso. Can you provide the model number?