I am trying to figure out the alternator on my 68 cutlass. The engine is a nom 350 with HEI ignition. The gen light has come on and gets brighter as you rev the engine, so obviously some type of charging issue. The car does not have a hooked up external voltage regulator so i assume the alternator has an internal regulator. Heres my question, i looked up the model number on the alt but according to delco remy website it is a discontinued 10DN. It is wired as an SI though with its 3 wires, and the old external regulator is not wired but is still attached at the fire wall. How is this possible? Has anyone seen this before. Is it possible to convert a dn to si internally? I’m thinking the previous owner did whatever to try to keep it original but upgrade it if thats possible. I am stumped. Its a delco remy 1102435-42 stamped on the case. If this one is shot, i wanted to replace it with a 10 or 12 SI. There are no large loads like a/c, pw etc so im thinking around 70amps is more than enough for this car.

 

Let's start with a photo of your current alternator, especially where the two wire connector attaches.

 

1102435 is a 10DN. It is the late style 10DN that looks like a 10SI internal alt. It is easily converted to internal regulator 10SI. The alt is not original to your year car. It was used only for a few years . I think the earliest would be 1970 - 1972

 

Isn't that 10DN-in-a-10SI-case from 1972-only?
And to the OP, if that's a rebuilt unit, chances are those cases were used to build an internally-regulated alternator. Again, a photo of the wiring connector would clear this up in a second.

 

All wires, bat wire and other two, go to the terminal block at the horn relay and branch from there. There is no external VR hook up. I realize this is not original, neither is the motor or trans, but I think the guy who restored it around 2005, tried to make it appear original as possible, Hence using an older one and converting




DN and rebuilding it.

 

Not to get off the subject too far here but I have only found the “10DN masquerading as a 10SI” in 72 cars. Certainly appears to be some sort of transition thing but any idea what the reasoning behind that was?

 

This is the money shot. You have an internally-regulated alternator. You don't need the external regulator. You need to ensure that the wire harness is correctly modified to accommodate this alternator.

 

I can't answer definitively, but keep in mind that after experimenting with the 10SI alternators on the 1969-71 442s and Toros, Olds dropped them for the oddball 1972 model year. I suspect this is yet another casualty of the rush to reuse the 1971 A-body models as 72s when the colonnade cars were delayed at the last minute. No wings, no red inner fenders, no inline six engines either for 1972.

 

Guys
Thanks for your replies, it confirmed what I thought. As far as the wiring all alt wiring goes to the terminal block at the horn relay and branches from there, i assumed it was done correctly as everything worked fine and has I guess since it was restored. As I posted firstly the gen light has come on while the car is running. It started a couple weeks ago but just at a low idle until the engine warmed up and rpms increased then it went out. Now it stays on and gets brighter as rpms increase. If its not an internal to the alternator problem I have no idea otherwise, since no one has messed with it since I've had it and it was fine till now. I guess I should have it checked out first before replacing it regardless, but I'm not necessarily interested in having it rebuilt to keep the 1970's case which isnt original to the car anyway

 

Pay attention to Joe's post #7. I think the guys are right about the odd ball 10DN style being used only in 1972. I have seen some dated 1971 but they were probably for 1972 production models.