Alternator Pulley | Ford Escort Owners Association (FEOA)

Alternator Pulley

Discussion in 'Electrical' started by novanutcase, Oct 13, 2018.

  1. novanutcase

    novanutcase FEOA Member

    Messages:
    2,317
    Likes Received:
    536
    Trophy Points:
    263
    I've been thinking about installing a larger diameter pulley on the alternator to up the amps it generates especially since I installed a UDP.

    Are there any suggestions to any companies that make a larger pulley to increase the amperage output or one that fits our alternator shaft from another vehicle? I'm running LED bulbs which keeps amp needs down but when I get a sub in their with an amp it's going to up the amperage needs and I'd like to be on the safe side and not overtax the alternator.

    John
  2. 1993tracer

    1993tracer FEOA Member

    Messages:
    153
    Likes Received:
    21
    Trophy Points:
    168
    Hey,

    Do you know about how many amps you saved by installing LED lights for the headlights and all the regular running lights ( not turns signals). I figured about 5 amps with 25 watt headlights. I saw a post at ecomodder with a guy with a zx2 that he checked amps with everything on ( map lights, blower, headlights, etc) and got about 40 amps at idle. I figure a 25% underdrive and saving about 5 amps ( about 11%) should help balance out the loss in generating capacity. Do you have any problems with your current setup and how much underdrive do you have?
  3. novanutcase

    novanutcase FEOA Member

    Messages:
    2,317
    Likes Received:
    536
    Trophy Points:
    263
    I think the UD is 25%. No problems with the setup. Trying to find the time to setup the switchbacks on the turns.

    John
  4. denisond3

    denisond3 Moderator Staff Member

    Messages:
    9,841
    Likes Received:
    2,630
    Trophy Points:
    563
    Location:
    south TX or northern VA
    I dont know of larger pulleys, but if needed would try a place like Grainger, that might have listings of standard pulley sizes.

    Would not a larger pulley on the alt spin it slower, thus resulting a somewhat less output? I never thought you could get more amps by doing anything other than having an alt rated at higher amps - and I think of the limitations there as being due to the wire size (gauge) in the harness going to the battery.

    I have seen two sizes of pulley on my 2nd gen alternators. The smaller ones being about 2.5" at the rim; the larger ones being about 3" at the rim. The smaller ones have a part # of FOCZ-10344-AA. Sometimes rebuilts come with no pulley, and I take the pulley from the old one I turned in .
    zzyzzx likes this.
  5. novanutcase

    novanutcase FEOA Member

    Messages:
    2,317
    Likes Received:
    536
    Trophy Points:
    263
    Any idea what the shaft diameter is so when I go looking I can get the right one.

    Oops! Yes. I meant a smaller pulley. Not so much to pull more amps but to make up for the smaller UDP I have on the motor. Maybe it would be best to hold off and install all the electronics I want and then see if the alternator is up to the task. I've seen 95 amp alternators but remember someone talking about an alternator from a Ford Van or truck that was 100+ amps in the same alternator casing that comes in our cars.

    Good info. Thanks!

    John
  6. denisond3

    denisond3 Moderator Staff Member

    Messages:
    9,841
    Likes Received:
    2,630
    Trophy Points:
    563
    Location:
    south TX or northern VA
    My micrometers are rusty from age, but measured the shaft on the alt at .669" which likely amounts to 17mm. The pulleys slide over the shafts with no effort, so may be .001" or .002" larger diameter.
    A caution; there are five groove pulleys in the same diameter (rockauto even listed one for an Escort) but LX Escorts take a six groove pulley. I worked on a 96LX that had a five groove pulley on the alt, and it was slowly damaging the edge of the serp belt.

    An ebay seller is listing the pulley part number FOCZ-10344 as being for a Ranger, Taurus, Escort, and Lincoln. So it must be a pretty common shaft diameter.
    Tnashua and zzyzzx like this.
  7. zzyzzx

    zzyzzx FEOA Member

    Messages:
    14,592
    Likes Received:
    1,057
    Trophy Points:
    463
    Location:
    Baltimore, MD USA
    Yes!
  8. novanutcase

    novanutcase FEOA Member

    Messages:
    2,317
    Likes Received:
    536
    Trophy Points:
    263
    You da man! Thank you! Any chance of getting a measurement on the outer diameter of the stock pulley itself so when I order or better yet find it on another vehicle I can determine how small a pulley I'll need?

    I'll post my findings in regards to UDP diameter as to what the proper size pulley will be to return to stock alternator rpm.

    John
    Last edited: Oct 17, 2018
  9. denisond3

    denisond3 Moderator Staff Member

    Messages:
    9,841
    Likes Received:
    2,630
    Trophy Points:
    563
    Location:
    south TX or northern VA
    I only measured across the diameter of the raised rim, at each end of the grooved section. The 10344AA was about 2.5", so the diameter where the serp. belt would run would be about 2.3". The larger pulley was close to 3" in diameter, so the diameter where the belt would lie would be about 2.8". Sorry I dont know the mm dimensions. Im old enough to have grown up with all dimensions in inches.
  10. novanutcase

    novanutcase FEOA Member

    Messages:
    2,317
    Likes Received:
    536
    Trophy Points:
    263
    No worries at all! That is exactly what I need to know. I'll post my findings for future reference for other members.

    John
    denisond3 likes this.

Share This Page