A 7294 12 SI is a piece of junk. Flat turbine fan. Moves around 40% of the air of a finned fan.
A 03/02 wound Wye stator. A veritable toaster iron winding. Hovermale winced when I told him a West Texas barbed wire fence had more integrity.
The CS144 has the same mounting as a 15, and 17 SI. It is NOT a drop-in for the 10DN, 10,or 12SI. The numbers in the CS series, 130 and 144, designate the millimeter diameter of the case, The 130 is interchangeable with the 10, 12 SI and the 144 can be swapped for the 15 or 17 SI. Bolt-on but with a different regulator plug for the case.
The CS-144 is a GOOD alternator when built right. I insist on factory wound rotor and stator. The 140 amp Cadillac windings are the best. You MUST use a gull wing "sawed thin" rectifier with all 6-avalanche rectifiers to make the unit last. Either a 1116437 or a 1116425 voltage regulator is the best of the lot. If your rebuilder is not INTIMATE with this terminology RUN LIKE HELL!
The 12-SI can be salvaged. Frisbee the disc fan over the back fence. Tell your rebuilder you'll buy him a sixpack of Corona if he can dig up the earliest type of 10DN Delco fan, the one that has 13 sharp fin points evenly spaced around the circumference of the fan NO FLAT FIN EDGES! He'll need to re-space the fan from the housing with different rotor shaft spacers. A piece of cake. Life or death cooling difference for the alternator internals.
SCHOOL. The 55 and 66 amp 12SI alts HAD AN INFERIOR ROTOR WINDING SPOOL. The 7278 and 7294 rotor spools were fully wound with wire. The 66 amp was not and that was the only difference between the 66 and 78 amp alternators. Kapisch? Your motorhome came with a 66 amp from the factory. unless you upgrade the rotor, trash the 12 SI project utterly. Horribly inferior low RPM performance.
Beware of your rebuilder. Test him with some of this info. Most do not know squat from dark Shinola about this stuff.
So I'm going to furnish you with a name and number for a good rebuilder a titanic rebuilder in the Northwest.
ROMAINE ELECTRIC
1-800-426-5005 ASK FOR ALAN
Tell him you want something more potent than a 7278 but absolutely not a 7294 unless their sister company Lund & Flynn(rewinders) provides a stator different than the factory 7294 winding. Why the heck not - ask Alan if they have any new original 10DN Delco 13 blade fans.
Romaine is brutal. They rebuild tens of thousands of units and cannot afford comebacks. So they use good dependable voltage regulators and rectifier bridges.
Let your rebuilder deal with the 10DN/12SI spacing issue. A 1-G or 2G Ford fan spacer is involved. But you'll end up with a hard low-speed charging alternator that'll last 100 grand and not turn the stator winding pitch black charred.
I used to order the 13 fin fans by the HUNDRED LOT CASE so I guess I have some experience with these units used in motorhomes.
I had a "ringer" special model 12-SI that I used to tease with. Marion Hovermale, chief engineer of the Delco CS alternator projects could not believe what he was seeing - 4,500 alternator rotor RPM and 167-amps HOT (110c+) "Can't be!" he exclaimed. "How in the world did you....?" The man was LDS so he didn't curse. When I tooled up a CS-144 and it spit out 93 amps at one thousand six hundred rotor RPM he sat back on my spare stool. Oh the days! Tempel Steel Temcor laser cut stator laminations. Slow bake pure iron rotors, .006" rotor stator DIAMETER difference. Elmer Trapp at Ace Electric Columbus Kansas winding rotor spools with a LEVEL WIND. Kynar wrap wire.
All that - every bit of it is now worthless 25 years later with the advent of the HAIR PIN alternator. But it was worth it.
Call Alan. He'll fix you up.
