View Full Version : TR2/3/3A Delco Alternator on TR3

02-29-2008, 05:06 PM
I just finished working out the mounting of a Delco 10SI alternator for the TR3 engine. Belt alignment looks real good without having to modify the drive end housing. I'll know better when BF&E sends me the six bladed water pump and get that mounted. But from what I see, I won't have to change anything. I made a spacer for the adjusting arm where it attaches to the water pump housing. Since I had the rear part of the generator bracket doing nothing, I made up another small bracket to take advantage of the rear mount on the slip ring end housing of the 10SI.

All in all, I like how things turned out.

02-29-2008, 06:12 PM
If you flatten the adjustment bracket, it should line up perfectly with the front pulley. It still looks just a bit forward of the crank pulley.

Mine didn't need any trimming of the alternator either on the 3A.

Once you get it running, be SURE that the bottom bracket holds the alternator from vibrating. I had a problem with a harmonic that 1st) broke the bolt at the waterpump and then 2) broke the adjustment bracket at the waterpump end. The 3rd time, I cranked down the lower bracket really tight against the spacer between the ears. That seemed to fix it.

Looks like a nice job you're doing.

02-29-2008, 08:17 PM
Once you get it running, be SURE that the bottom bracket holds the alternator from vibrating.

That's one of the reasons I decided to add the bracket in the rear, rather then a spacer between the ears. I think it will give better overall support. Also, I'm considering drilling out the drive end housing to accept a 1/2" bolt, as that is the size of the hole in the front part of the bracket.

As far as flattening the adjusting bracket, I want all of the mods I'm doing to be reversible, so the spacer was the choice I made for this.

02-29-2008, 08:42 PM
From my failures, I think that you NEED a spacer even with your setup. I used a long bolt the first time, no spacer, but double nuts around the front ear. One ear wasn't enough to keep it from vibrating and breaking the bracket from metal fatigue.

Mine was a difference between solid and rock solid. Solid broke. Twice. But I didn't think of a rear bracket like you added so who knows.

Just add a piece of tube on each side of your rear bracket, so the whole thing tightly spans the gap between the ears. Then crank down on the bolt to squeeze on the tube.

Did you go to thin belt and harmonic balancer?

04-05-2008, 06:06 PM
Sorry, but I'd like to resurrect this post as I'm also converting over to an alternator sometime soon on my TR4. I'm also switching to a thin pulley setup like that sold by BPNW.

Just wanted to make sure - for a 10si, no case mods are necessary to get alignment? I think for the 7127 there is need to remove material from the case, but was under the impression the 10si and 7127 cases were basically the same - not true?


04-05-2008, 06:18 PM
Mine is a 7127-3 and didn't need the mounting purch mod'ed. I've read to grind off 1/2" but not on my 3A.

04-06-2008, 08:35 AM
I put on the thin belt conversion, and everything lined up perfectly without any mods to the alternator.

BTW, 7127 is the Lester catalog number for the most popular version of the Delco 10SI alternator. The -3 or -12 etc. indicates the clock position of the harness plug when the bottom pivot mount is straight down as you are looking at the back of the alternator. This method of naming clock positions is used on all alternators that can be 'clocked'.

04-06-2008, 08:55 AM
Thanks all. It is a little confusing - I've seen photos for a TR4 where about a 1/2" of case had to be removed from the lower mount to get alignment. Here's an example:
tr4 mount (https://projectsgardentriumph.blogspot.com/2006/05/my-alternator-conversion.html)

It might just be due to differences in alternator fan/pulley geometry. Probably the only way to figure it out is to go out an buy one and start test fitting.