mikevillena

I have a 1979 SA22C that has been converted to a road racing car back in the 90's (I'm guessing based on the SCCA log book that came with the car). I bought the car sight unseen back in 2018 (non-running). First thing I did was to document the rudimentary race car wiring system which consisted of powering an electric Holley fuel pump, twin MSD ignition, starter, tachometer, water temp gauge and brake lights. Since I intended to drive the car to the track and back, I added headlights, turn signals, hazards, dual electric radiator fans and additional relays that were required. I rewired the entire car with fresh heavy gauge wire and used new fuses (old fuses were glass bodied), fuse box, relays, etc. The car eventually ran after I spent countless hours troubleshooting the Nikki carb and managed to compete in 3 races last year. However, the alternator that originally came with it failed after the first race and I replaced it with a reman unit from the auto parts store. I might have used the incorrect one or wired it incorrectly but I did not notice it until I was at the track and noticed the tach needle bouncing. I thought the tach was failing and needed replacing so I soldiered on with the race but had to eventually retire due to fuel starvation problem (I had re-routed the fuel safety cell vent tube which acted as a sink gas trap and caused fuel starvation). I managed to drive the car home by removing the fuel safety cell fill cap. Anyway, the reman alternator failed when I was driving to the track (had to have the car towed home) and I replaced it with another of the same type. For the last race in October, the alternator failed during the first practice session (tach needle started bouncing and the battery was nearly dead). Fortunately, another driver with an FB had a spare alternator which he lent me. After I replaced the alternator, I decided to not push mu luck and went home. The battery was charging and the tach needle behaved normally. I apologize for the very long story but I wanted to give as much background as I can. I am thoroughly confused as what the correct alternator to use regardless of model year. I am assuming based on the way the race car was wired when I bought it: A) the voltage regulator is internal to the alternator and B) there are only three wires to the alternator with one wire from the ignition switch to provide 12v to energize the alternator (non self-exciting type)when the switch is on, one wire to ground and one wire with a manual kill switch to the battery. I read all of the posts regarding alternators and I am unclear as to which one to use. I am looking for recommendations based on the car's need and how it's wired. Thank you.

PS. the car is plated for street use and I drive about 150 miles to the track and another 150 miles home.

GSLSEforme

Car has a lot of non stock electrical consumers.
Possible what you had for an alternator was not large enough(enough amps). Reading thru your post,I would think90-100 amp alternator would be adequate to supply all electrical needs and a small reserve.

Reman build quality always an issue,new would be best.
FD alternator from 92 up would be a bolt on. You’ll need to convert serpentine pulley to dual v belt pulley and wiring is slightly different for this alternator than wiring for FB,FC cars.
I will post wiring schematic later when home.

Be sure your battery is good and all wiring in car is as it should be.

GSLSEforme

FB,FC- Alternator use S4 wiring.
FD Alternator use S5,S6 wiring.

mikevillena

GSLSEforme - Thank you. Since I don't have standard wiring on the car, I am unsure of the wire that's labeled as going to the dash. I'm assuming that it grounds out the "ALT" light when the engine is not running or if the alternator has failed and is therefore (-) ground and the other lead to the said "ALT" light is (+) from ignition switch ? I'm currently on the fence regarding installing an "ALT" light but given the frequency of alternator failures that I've experienced, it might be a good idea. If my assumption is correct, then I can install an "ALT" light with a positive wire from the ignition switch (aftermarket shrouded toggle on the far left) and a wire from the "L" terminal on the alternator as marked on your diagram? BTW, the photo shows the wiring in progress during the build last year but I've left the wires easily accessible so as to make troubleshooting easier. I am also uneducated as far as the designations of "S4" & "S5"; are those the sub-models of the car? I am hesitant in converting to dual belts and would rather go with the current single belt/pulley setup and not introduce another variable. Incidentally, the alternator that came with the car worked well until I did a last minute rewiring of the external main kill switch in order to pass tech inspection to get on track (2nd race last year). I believe I disconnected the wire that connects from the external main kill switch to the battery so that the engine stops when the kill switch is off (essentially, the car was running on battery power only). I drove the car from the paddock to the tech inspection building, got the car to pass tech, drove back to the paddock and reconnected the wire. I suspect that the alternator output went nowhere for that period of time and could have caused the demise of the alternator. The external main kill switch was a cheap "made in China" that I threw in because I was running out of money then so the quality was rather dubious. I've subsequently connected that particular wire directly to the positive terminal on the battery so that the alternator output goes directly to the battery. Again, I apologize for the long winded post.


EDIT: To clarify, I have two kill switches installed and wired in series; one is the main (external) and the other is on the dashboard downstream (as pictured).

GSLSEforme

Yes in answer to your question of wiring in an idiot light for alternator charging and yes in how to approach it.
Strongly recommend dual sheave alternator pulley on any rotary not running an air pump.

The alternator belt doesn’t have quite enough traction to prevent slippage with stock alternator and a larger(higheramp)alternator takes more power to turn under higher electrical load.
This is a reliability issue as with belt slippage comes heat and heat cooks grease out of drive bearing in alternator ultimately causing bearing lockup and belt failure.

Tightening belt tension more(over tightening) to overcome slippage is detrimental to front e shaft bearing.
Dual belts doubles traction on pulleys without increasing load on e shaft bearings.

S designation describes different RX7 year models and alternators that came on them.
All physically interchange all years and generations but wiring is different dependent on the actual alternator used.
The latest generations S5-S-6 are the most powerful in stock configuration. Their cases are slightly larger making slightly longer drive belts necessary and some S-5 and all S-6 alternators have a larger 17mm shaft versus the earlier alternators 15 mm shaft making it important to measure the shaft on the one you gave when ordering dual sheave pulley.

They can be had from Banzai Racing,a vendor on this forum. They also sell a belt adjusting bracket with hardware that’s highly recommended to achieve exact belt tension without over tightening.