I installed the standard 123 distributor in my 1976 U.S. 49-state 2.0 Alfetta which is running Alfa GRP.1 cams (10.92 lift, 246 duration, 83 overlap, Rank 8L), Euro cast iron headers, Wes Ingram's HP Spica pump, totally desmogged but otherwise a stock engine. The 123 is connected to an MSD STREET FIRE multi-spark box with Blaster coil with no ballast resistor. .035" gap on BP6ES plugs. Yes, 123 says you can't do it, but everything works fine (with one exception, noted later). I had quite a time initially adjusting the distributor. I found TDC using a dial gauge on No.1 and turned the distributor until the green light just came on, but that put me about 20 degrees advance at idle! After messing around with it I now have it set at about 3 to 5 degrees advance. My problem is two-fold. First of all I don't know how many degrees advance the M mark represents on this "emissions" engine pulley. As you may know, in stock the engine's set at 6 degrees ATDC (not BTDC), and the Owners Manual and others don't tell what the M mark is! Does anyone out there actually know?
Dumb me, I had the crank pulley off when I installed air conditioning but I never degreed the pulley. To get the pulley off now involves unbolting the engine mounts and exhaust system and raising the engine as high as possible to clear the crossmember because now there's a 6 groove serpentine pulley welded onto the Alfa pulley for the A/C. It's hard enough peering down below the compressor, past the wide belt, and through all the plumbing to see the crank pulley marks. But I'm going to have to temporarily glue a degree wheel onto the front of the A/C pulley and mark the Alfa pulley correctly. Later.
In the meantime it runs well using the distributor curve #1. It does have better torque pulling away off rest at low RPM which is especially desireable when the A/C compressor is engaged. I have thought about trying the "D" curve but I don't think my engine's been modified enough (no high compression, for example).
My second problem is trying to figure out how to make Alfa's electronic tach work with this new ignition. MSD gives you a "tach wire" that must work in some applications, but not with the Alfa. Another suggested hook-up is to attach the tach wire to the wire coming from the distributor, but that doesn't work either. In trying to figure out which wire is which coming out of the engine bay harness I discovered that Alfa's wiring diagram does not show an electronic tach! Presumably the diagram they give you must have been for early Alfettas with a cable tach... Any ideas out there on how I can get RPMs again?