Realistically, how many Amps does our alternator need to produce?

Earl, I don't really need the part number, I just need to be sure the bolt holes line up and the plugs are where they are supposed to be.

Are they all the same? Will the truck ones fit the mustangs and 5.0s in our cars?

 

You have to make sure that the bolts are 180 degrees from each other. Those are the ones that fit our cars.

example

 

THANKS That is what I needed to know.

 

The case halves can be clocked to get the mounting holes to line up even if they don't originally. I got my rebuilt 150 amp 3G on eBay for $100 shipped. Pay close attention to the rated output at idle. Picture sitting at a red light at night with all your lights on, brake lights, stereo, igniton box, fan comes on, etc. In my case my Taurus electric fan draws 43 amps, brake lights (Shelby, 6-bulbs) 9 amps, rest of lights 16 amps (halogen headlights), ignition 8 amps, for 76 amps total needed at idle.

 

You should always figure out your amp draw and double that for your alt output. Watt=volts * amps. 840 watt 13 inch 2200 cfm cooling fan (just installed one on a 69 chevelle) draws 70 amps! And alternators just like everything else are variable. At idle a 135 amp alt might only put out a couple dozen amps. And don't skimp on the cable size from the alt to the batt. Small cables add resistance which creates heat that eats up amps.

 

in an automotive class i took we disconected the alt on a tauras and put a clamp on amp probe on the neg cable to the bat. then we turned on each eletrical circuit to see what it would draw. the the bigest draw was the rear window defroster and the second was the air conditioning. the fan when it turns on has a good sized spike of around 50 amps but once its up to speed the amperage dropped below 20 amps.

 

Well, I bit the bullet today and just bought an Ultima 130A alternator from O'Reilly. It was $150 and said to fit 5.0 mustang. So I think I got the right thing, just not for $40-60 like everyone else is.

 

Strange. My Taurus fan draws 11.5 amps on the low speed and 43 amps on high, high speed spike is almost 80 amps. Different years maybe?

 

My 130amp arrived today. It's suppose to be bolt and go - no mods on brackets or alt housing. I will see in a few days.
What type of belt setup ur running? I am using the V-belt. Mine is suppose to be one wire hook-up. What gauge wire do u plan to use? I have some 4 gauge left over from stero amp install - I plan on using that.