by Rich Cwik
Did you ever wish to enter one of those contests where the loudest car stereo wins a big trophy? (This is Bob Herzog's secret desire). (Actually, my secret desire is to be able to HEAR my stereo while the engine is running! - Ed.) How about having Real headlights and a radio? As most of you know, the Europa Twincam alternator's output is a mere 35 amps. If your car has been converted to electronic ignition (MSD, Allison, Luminition) and you have your headlights on, you're usually losing ground in the amperage department. Here's a difficult and expensive (if I said cheap and easy, everybody would try it) way to satisfy your every electrical need for years to come.
As a starting point, I chose a 1987 Grand Am alternator. This has a case size exactly the same as a Twincams but it has 105 amp output! Times sure have changed. Now to make it fit the car.
Since I started with a junkyard core alternator, I got to disassemble this thing to do the machining part. If you start with a good alternator, you'll have to be more careful than I was. The front mounting point on this case has a big honking boss where the TC's is fairly flat, so it's time to fire up the Bridgeport. Machine off the mounting boss until the overall thickness is about .430, as this will give you the stock Twincam pully/cam offset (see sketch). This needs to be machined flush with the case all the way around, so that the belt tensioner will work. If you go to far into the case, you may nick the stator winding (like I did). Good thing it was a clunker to start out with. You can use your stock pully or search the junkyard for a pully since the Grand am alternator uses a serpentine belt.
Step 2. For a rear mounting ear, all the GM/Delco alternators use a bolt-on plate on the rear of the case. I made mine out of a scrap of 3/16" plate and an old piece of 1/4" drill rod. Make a little triangle with the drill rod sticking through the plate and into the locating hole in the back of the case - don't go too deep or you'll short out the diode plate. The tube welds to the plate and touches the back of the mount on the trans. This plate bolts to the alternator with a 6MM. bolt - all the new GM stuff is mostly metric. The stock Lotus bolt goes through the tube , trans. frt., alt, plate, and - PRESTO - its on.
Last step - wiring. This step is easy - even for a guy like me. Stock Twincams (without Lotus East - Motorola nightmare) have 4 wires on the back - big black, big brown, brown/yellow and brown/white, in two plugs. Take them out of the plugs. The big brown wire goes to the big + terminal, and the big black grounds to the case under the 6 mm. bolt on the mounting plate. The brown/white wire goes to the ammeter and should also be put onto the big + terminal. The brown/yellow wire goes to the "ignition" light on the dash and goes on the plug on the side of the alternator. This plug can have as many as 4 wires, labeled "S","F","L"&"P". On the Grand-Am only the "L" wire is in the plug (it's the only one you need.) The brown/yellow gets connected to the "Light (L) terminal. That's all there is to it.
Now, the cost. One of my favorite sayings when someone asks me about a problem on there car: "No doubt about it, that wallet has definitely got to come out!" If I had known how expensive Grand Am alternators were, I probably would have used the alternator from my Chevy pickup. Expect to pay $160-180 for a rebuilt Grand-Am 100 amp plus a $35 core charge. Chevy pickup truck alternators use pretty much the same case, starts a 65 amp ($75) up to 150 amp ($177), and the machining is much the same. You may want to switch to a bigger ammeter (like 0-100 instead of 0-30), if you actually intend to use all that power(!!!)
One last bit - you may have to tweak the tensioner bracket a bit, or junkyard around for one. The one on my test car wasn't stock and I had to tweak it just a bit (I added more curve). This test alternator - if you would like to see it - is installed in Jim Cowen's Europa. See it at the tune up clinic, or call me and we can talk about updating your alternator for a slight fee!
OHHH! It's Little Feat - Turn up the Bass!
