by Steve Crowley
with additional comments by Rich Hirsch
[This article is about replacing a generator in an older car. I too did this recently, so I've added some comments based on the experience. RH]
In the process of getting my Duetto jump-started, I apparently fried my generator and was just running on the battery for a week and a half. The funny thing about generator systems is that you have to get the generator and the voltage regulator checked out at the same time or you will ping pong back and forth between replacing the generator and voltage regulator. Since my voltage regulator is always on back order from Germany, I had to look for another option. I called Mike Besic at Besic Motor Sports and he said, "Pitch the generator and use an alternator from a newer Spider. It has a built in voltage regulator with only two wires to hook up and IT BOLTS RIGHT IN." Remember that line. It ranks right up there with the check is in the mail.
The generator came off without any problems. The original generator bolt was too short to use on the alternator because of its thicker mounting flange. [I found that a M10-1.5 x 113mm "GM starter bolt" is just about a perfect fit. RH.]. Also, the diameter of the mounting hole is larger on the alternator than the corresponding hole in the block. Since I really didn't feel like drilling out the block, I chose to sleeve the bolt where it passes through the alternator. Mike Besic supplied me with some metal tubing from the hydraulics off of some truck. [I used some 0.25mm aluminum sheet wrapped around the bolt as a sleeve. RH]. With the alternator ready to be mounted, it had to be shimmed out with a stack of washers to align the fan belt pulleys.
Now I was able to try and fit the fan belt back on. After arguing about an hour, and unbolting the radiator to get room to work, I finally just pitched the stock belt that Mike was so insistent on me using. [I suggest you remove the radiator and fan before starting to make this job easier. RH] Trial and error, and three trips to the parts store helped me to decide on a fan belt that was 1½ inch longer than the stock 1600 fan belt. It puts the alternator all the way at the end of the slide bracket which keeps the fins on the alternator from hitting the bracket. [I ended up using a 31 inch belt (Dayco 15310). If the original generator slide bracket is used, you have little choice but to mount the alternator at the end of the bracket. If a "bent" slide bracket is used, the kind normally installed on alternator equipped cars, you have more flexibility and can use intermediate bracket positions. But don't expect to be able to tension the belt as you would on a modern car. The alternator has a larger diameter than the generator and even with the "bent" bracket you're severely limited. At maximum extension the alternator hits the air box snout and at minimum extension it hits the water pump. I was able use a bit more of the bracket by cutting an unused mounting tab off the water pump. However, the effort involved in pump removal, cutting, filing, and remounting may not be worth the extra ½ inch travel gained. Be careful of the fan shroud also, it may need to be notched. RH]
Now for the wiring. I ran a 12-gauge wire with soldered-on eyelets from the alternator to the starter. The second wire goes from the other post on the alternator to the gauge light on the dash. Rather than running a new wire all the way to the gauge and through the basket-of-snakes wiring system under my dash, I traced the wire in question from the gauge to where it used to hook upto the old voltage regulator, and plugged it in there. On my car, if was a blue wire. Don't ask me what color it was supposed to be. Surprisingly, it all worked.
My first trip was out to Mike's to show him it worked. He liked the fact that I took the time to polish the alternator housing. After checking out my work, he said, "Cool, I never put one of these on a 1600 before."
[It shouldn't be necessary to run any new wires. The 4mm blue wire and the 1mm black wire that previously connected to the generator can be used to connect the newly installed alternator. Crimp and solder a ring connector on the 4mm blue wire and connect it to the "+" mounting post on the alternator. Connect the 1mm black wire to the other alternator terminal. Next, remove the old voltage regulator and connect the 4mm blue wire attached to terminal D+ to the 4mm red wire attached to terminal B+. Then connect the 1mm black wire attached to terminal DF to the 1mm blue wire attached to terminal 61. I used a one-connector terminal block to connect the 4mm wires and simple spade connectors for the 1mm wires. It should help to look at the illustrations below, although these illustrations are for installing an older-type alternator with an external voltage regulator. RH]