Today I stopped by the autoparts store and picked up an alternator I had been researching for a while. I decided to go with an auto unit rather than an aviation version for a few reasons:
1) they are basically the same, there is no big advantage to the aviation version 2) Ease of replacement. Alternator failure isn't uncommon. With the auto version I can just get a lift to any parts house and pick up a replacement and be on my way. 3) Cost. The aviation version is around $400 with the install kit (bracket and belt), All told I will be into this alternator and regulator for around 170 including the mounting bracket, regulator, and the core charge.
Since my goal is to have an easily replaced alternator, I can't make any major modifications to the alternator that could not be easily done in the field on a replacement.
My first action when I got home was to make sure that the alternator would fit and not interfere with the cowl. The fit is tight, but that is normal for the alternator. It s hard to tell in the picture, the there is around 3/4" clearance. That is with the alternator all the way up, so the belt length has to be as short as possible.
The next problem is the pulley. The pulley that came on the alternator is a six-rib belt. That won't do with the lycoming v-belt drive. The engine I bought came with a very old DC generator. The gen has the same shaft size as the alternator. The hub on the Gen pulley is too thick for the alternator since the shaft length is different. I used my rivet-shaver bit like an end-mill in my drill press to remove some of the flange material on the hub. It came out great!
