Not my strongest day... Presently going crazy, need help - timing & mixture

[35-709]

Jeeez, no fair!   

[JVA]

I know - I don't even get the satisfaction of finding the problem.

I couldn't quite let sleeping dogs lie, so I tried starting it again... one pump of the accelerator, 5-10 seconds of cranking, and it fired right up. As much as I'd like to know what happened, I'm not going to look this gift horse in the mouth.

[Jeff Rosansky CLC #28373]

First of all, may I say that I am pretty impressed with the fact that you still have the little plastic knob that resets the trip odometer. 
Secondly, I wonder why when you turn the key off the gen light comes on.  I'd have to look at a schmatic but I wonder if the switch grounds the generator which kills the generator and therefor turns on the idiot light.  That however may make a direct path to ground which would keep it running??
Have you let her run with the switch off to see how long it will run before it dies on its own............ or if it will just keep running?  If it's just an energized coil it should die when it de energizes.  If there is a direct path then it will keep running. 
If it keeps running then you just disconnect things until she dies.  Then you know what you are dealing with.
Just a thought.
Jeff

[JVA]

For better or worse, this car is VERY original. I think it was casually driven its whole life - so that means it's fairly well used, but by the same token reasonably well kept up. There is a stack of Colorado inspection stickers piled up on the windshield.

I have not let the car run for more than a few seconds with the key off. Until I know what is causing the situation for sure, I don't want to risk frying anything with big voltage running the wrong way through wires not designed to take it. Of course, since there a relay is running all the big draw stuff, that risk is very minimal - it would take more than 200-500ma to keep that relay closed and keep things running.

I am looking at the wiring diagrams now - I have very little experience with external voltage regulators.... the only other car I own that had one is my '62 Falcon, and the first thing I did after buying it was install an internally regulated alternator. I'll see what I can learn from the diagrams. I suck at carbs, but I'm reasonably good at electricity.

[JVA]

Well, the wiring diagrams make a remarkable amount of sense, and after some Googling it seems this problem is common with this-era GM car. With the key on, 12v from the battery flows through the key to the GEN light, and the stationary rotor in the alternator acts like a ground. Once the alternator is spinning & energized the ground disappears so the light goes off. In a stock car, when you turn the key off you power down the coil, and whatever juice is coming through that light circuit is not sufficient to power anything for more than a fraction of a second so the engine stops and everything returns to zero. In my situation, the tiny amount of voltage coming through the light is enough to keep the relay powering the ignition system closed and so the engine just keeps running. At that point, the GEN light functions backwards - the alternator provides the 12v, the ignition switch provides the ground. Installing a diode in the GEN light circuit prevents the positive flow from the alternator from "getting into" the gen light and keeping that relay closed, so the car should shut off.

Apparently this is very common on early GM cars with external voltage regulators, and even some early alternators with integrated regulators (10si). It does not seem to be a problem with 12si and later alternators. A diode will fix the issue on the earlier models in any case.

Since I want to upgrade alternators anyway, I think I am going to just buy a CS130 alternator from a '90s GM car and install it. From research I think the low-amperage (105a) versions have the same case size and dimensions and should bolt right in. I can lose the external voltage regulator, the run-on, and keep two batteries safely charged even at low RPM without any major visual impact. Visually I'd prefer a 10si or 12si alternator, but there is a real advantage in the CS130-series parts - they run cooler and have better low-rpm output. With a 500rpm idle, low RPM output is the name of the game. Since I'm planning on redoing battery cables anyway, now is the time to perform this upgrade!

One ACDELCO #3342369A  105a alternator en route from Amazon.com... $65.

[Aprules2]

Im not sure if this helps or not, but I had an 86 cutlass that the previous owner put a Mallory distributor and Holley fuel pump in. I thought Id make the fuel pump and distributor work better by relaying each one, and had the exact same problem the relay would stay engaged and my car wouldnt shut down. So if youre new alternator cross references to an 86 cutlass with a 307 you may still need to install a diode. I ended up putting an HEI in and mechanical fuel pump.

[JVA]

I appreciate the tip! Looks like the 307 had a previous generation alternator - a 12SI - so maybe I will be okay. I did order in supplies for installing a diode, so if it comes to that, I'll be prepared.

[TJ Hopland]

I have found the 12's to be much better than the 10's.

One thing they don't tell you when everyone says what ever is a direct swap is the rear mount never seems to be the same.  Guessing this is because no one cares?   I have done a lot of swaps either on purpose or because its what I could get my hands on at the time and I don't think I have ever had the rear mount work out.    How important it is I don't know.  I currently have an Oldsmobile that for some reason the rear mount is not there and that is the first time I have noticed one making a weird vibration that stops when I put pressure on the back.   

[JVA]

I could definitely see how the rear mount would be useful for stabilization. I'll keep my eyes out for it!

[JVA]

The answer to this I posted here:

http://forums.cadillaclasalleclub.org/index.php?topic=129113.0

TL;DR, the alternator resistor wire was the culprit.

On topic, getting back into this project, the other day I cranked it over for a little while to get oil circulating, then left it sit for a bit. The morning I came back, cranked it for maybe 5 seconds and it fired up and set into a nice idle. Oil light off, gen light off. I left it idling for about a minute then turned it off with the key - GEN light off and ignition switch actually working are two things I could not accomplish previously, so I am 100% confident that Messed Up Resistor Wire was the explanation for all of my problems. *So much* dismantling and troubleshooting for nothing, something I could have solved with a pair of side cutters in a second.

At this point I am down to reassembling everything I took apart last year, and figuring out a solution for the variable stator and kickdown switch, since my replacement Edelbrock does not have a provision for the factory switch. That's my current project - I think all the major functional issues are in the past. The Fleetwood seems to start and run great!