This weekend I completed the generator to alternator conversion on my remanufactured 390. I bought a chrome, 100 amp, 1-wire alternator from Summit Racing. For brackets I used the custom generator to alternator conversion kit from Custom Replacement Auto Products (C.R.A.P.). These brackets allow you to use a FE that was drilled for generator mounting brackets, but not drilled for alternator mounting brackets. The kit is available in polished stainless steel, or powder coated black (what I used). The kit also doesn't care if you use a 64 or earlier water pump (with generator bracket dowel pin) or a 65 or later water pump (without dowel pin) as it doesn't use that particular hole. You end up with basically a low mount alternator.

The installation was more or less straightforward with only a couple of minor glitches. I had to remove the battery in order to provide enough room to pull out the old generator (dirty and very heavy) and to install the new alternator (shiny and very heavy). After removing all of the old generator brackets, I test fitted the new C.R.A.P. brackets. The first thing that I noticed was that the bolt supplied by C.R.A.P. to bolt the rear bracket to the side of the block was too big in diameter (This bracket bolts to the side of the block where the generator bracket bolted and provides a threaded boss on the front of the block for the long alternator mounting bolt. It appears to be made of 3/8" steel with a heavy threaded boss on the front. Very solidly welded together.). No problem, I just cleaned and reused the original bolt. This left a little slop in the bracket hole which actually came in handy when adjusting things later. Then I bolted the front bracket to the water pump. This is a very nicely made 1-piece, c-shaped bracket that provides the upper front mount and lower adjustment mount for the alternator. No need to juggle two separate brackets. When I tried to mount the alternator between the block and water pump brackets, it wouldn't fit. I thought it was going to be too big which upset me greatly. I pulled it out and tried mounting the alternator to the upper front bracket with the block bracket loosely attached. This worked. The slop in the block bracket mounting hole was enough to jiggle everything into place. I ended up also having to use some shims (three flat washers) between the rear of the upper alternator mount and the block bracket boss. I then bolted up the lower adjustment bolt and everything fit great.

Wiring was a snap. Just one wire from the alternator to the battery side of the starter solenoid. Since the generator voltage regulator was removed, I had to rewire the horn and main harness to the starter solenoid. I ended up butchering my new generator to regulator wiring harness so I could keep the color code more or less the same.

Then I had to find a new belt. A 43.5" belt put the alternator just about in the middle of the adjustment slot. I was now ready to fire her up. With the engine off, the voltage to ground at the battery side of the starter solenoid measured about 12.5 volts. When I started the engine, that point jumped to 14.5 volts and stayed there from idle to over 3000 rpm. Success!

I also finally was able to install the rest of my auxiliary gauges (Mechanical water temp and voltmeter. Already had a mechanical oil pressure gauge installed). The only negative about this setup is the fact that with the 1-wire alternator you lose the dash mounted charging idiot light. I didn't want to mess with an ammeter, but the voltmeter (hooked to the switched connection on the ignition switch) really jumps when the alternator starts running.

If all goes well, next weekend I will be replacing the stock Autolite 4100 4-bbl carb with a 625 cfm Road Demon. Wish me luck.

 

Thanks for all the info. You might post some pics when you get a chance.

I'm running a Chrome 100 AMP from Jeg's. But it is not a 1 wire deal. I'm not getting good voltage at idle, after 1200 rpm it's about 13 volts. My alternator has about 5 different terminal studs on the back, so I need to verify I'm using the right connections. There are only 3 wires coming from the harness for the alternator.