It looks like a made a rash mistake when planning (actually lack of planning) for my electrical needs. Requesting those more saavy to weigh in and provide a sanity check...also I'm hoping this post can help prevent others from making a costly mistake.

BL - I purchased the serpintine system for late a '80s camaro and shortly after ordered a full compliement of same-era accessories...my error: I went with a 105 Amp (108 max output) CS alt. I just assumed a modern set-up would be adequate.

Here's my thinking:

Dewitts dual fans - 30 Amp (26 actual) each = 52 Amps
PIII EFI with In-tank EFI pump 20 Amp (likely 18 actual) = 18 Amps
Vintage Air 19 Amp blower / 5-6 Amp compressor clutch = 24 Amps

All in all -max load could be approx 94 Amps without lights, radio rolling up/down a window...

Lights? Approx 8-10 Amps
Radio? Approx 10 Amps

Any thoughts? I'm going to check with Carquest today and beg for mercy on a trade-up option.

Is my logic flawed? It just looks like a 140A is the only option with this set-up. Also I made a call to Dewitts and Vintage Air and asked for the specs on each accessory--hence the numbers above. The PIIIs entire system is powered via a 20 Amp in-line fuse.

Hope this helps and I appreciate any feedback,

Rob

 

I just wanted to pass along some info on this.

I went back to Carquest and told them of my dillemma. They did offer to allow trade-in since it hadn't been run. That's impressive after nearly 2 yrs since purchase. The problem is that they didn't show any models avialable (greater than 105A) that would fit my late '80/early'90s serpintine set-up. My mounts are at 6 and 10, while the newer/bigger alts are at 6 and 12.

Of note, the parts clerk also installs high power sound systems on the side and told me of an alt/starter overhaul shop in town (Tucson Alt Exchange) that can re-wire the stator windings to allow a higher output...at approx $180.

So, I head down and discuss my dillemma with the smart guys at the shop and was told a few interesting things. First, they recommended I stay with the current one because it comes factory equipped on vehicles with higher electrical needs and does fine (ie Tahoes ABS circuits, 4 windows, DVD screens, rear area blowers...) and Second, they say what you gain at the top end, you lose on the bottom. Apparently, a 105A (all else equal) provides more juice at a lower RPM than a 150A or 200A. Of course there is a crossover point. For instance, my model makes 35A at 1600 Alt RPM upt to its max of 108A at 6000 Alt RPM.

I just thought I'd pass this tid-bit along. Looks like I'll sit tight, see how she does and have them re-wire it if needed.

r,
Rob

 

If you want to go with a 140a, here is a list of where to get them:

 

I told my NAPA to look up a '93 Fleetwood and they had the alternator in stock. I did have to separate the housing and rotate the back half to get the holes to line up where I needed them. The alternator came with a serpentine belt pulley which I replaced with a standard pulley to use on my '73.

Another thing to note: I've forgotten the particulars, you can search on the forum, but it is important to know whether or not your car has a generator light on the dash. I think if it does not, then you need a wiring harness for the new alternator that has an internal resistor.

Here's a link to NAPA for the harness with the internal resistor: http://www.napaonline.com/Catalog/Ca...C82_0006361351

Hope this helps.

DC

 

Thank you all...this is a great source of info. I will re-visit to see if one of these alt case styles will fit my bracket.

 

I feed BOTH my spal fans with a single 30 amp fuse...they run 26 TOTAL on start ~20 something on run I assuming 11" like mine....DeWitt types....

I have been running my '72 vette with a/c, spals, lights, and so forth with heavy wiring off a 108 amp rated old 17SI which a larger diameter thing with one pulley off a '79 Seville with RWDefoger.....it's plenty enough....

however getting somewhat rare and not in stock so much anymore....so going a CS144 from a junkyard with maybe a new regulator is the way to fly....

 

Mr Vette, thanks. I was wondering if I was victim of a mis-speak when I spoke with the tech at Dewitts. Yes, they are Dewitts 11" dual spals. In their literature, it mentions 21 amps for the single 16", so it makes sense that a single 11" would be less, not more...the figure he stated, was for max draw, so initial surge upon start-up makes a lot more sense.

I'm considering running single fan's sensor (grey wire) through relay for the AC. IE both on at temp sense trigger and a single auto-on upon AC engagement. Your thoughts on this?

r,
Rob

 

I'm just finishing up installing Vintage Air AC along with a new DeWitts radiator and twin spals. Vintage Air recommended having both fans come on with AC pressure rather than when the compressor is engaged. I picked up one of their trinary switches and replaced the binary switch in the drier. The trinary switch closes the circuit to the fans when the pressure in the AC system is high enough to need the fans to come on. This will allow the fans to run less than they would if triggered by the compressor.

DC

 

The a/c compressor cycles anywhere from every 30 seconds to every couple minutes or longer depending on the temps.
You certainly do not want it coming on with the compressor cycles nor when the system pressures drop depending on the set point of the trinary switch.
This would command high amperage starting draws far too often putting an unnecessary load on the electrical system and the fan motors themselves. (The condenser doesn't cool off immediately when the pressure drops)
The proper way is to to trigger the fans to continuously run when the a/c is on thru the a/c select switch in the console. The condenser needs as much airflow as possible anytime the a/c is on or cycling.

 

Thanks Noonie, I'm not that familiar with AC systems. I'm just trusting Vintage Air to know what is best for their systems. Does the pressure in the system swing enough that my fans will be cyling on and off frequently? Or, once the system pressure gets high enough, will it stay high such that the fans will run most of the time the AC is running? According to VA, the fan engagement pressure of the trinary switch is 254 psi. I'm having the system charged tomorrow and will monitor it for awhile.

DC