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Thread: Alternative to Delco 27Si alternators

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    Default Alternative to Delco 27Si alternators

    As many of you know I am assembling a new P400 6.5 engine and Bowtie 700R4 transmission for my M1028 rebuild. Every part on the engine is either new or rebuilt and restored to OEM condition. I am not robbing parts off my existing CUCV engine, but instead fitting the new engine with its own parts and accessories. I am now at a point in the process of deciding what to do about alternators. I purchased a pair of used alternators from a fellow SS member up in Pennsylvania who assured me that the alternators were rebuildable, however I just opened them up and they are rusted beyound repair. Looks like they have been sitting in a field somewhere exposed to the rain for years. No way are they going to be rebuilt, restored, and installed on my P400. Sorry, I'm just too picky.

    So my question is, are there alternative new Delco alternators which would be a direct bolt-in fit? I went to Delco's website http://www.delcoremy.com/find-a-part...etails/1100080 to make sure that the 27Si was indeed obsolete, which it was, however the page also had a link to Upgrade Options. When I clicked there, a 22Si replacement unit, part #19020310, seemed to suggest that it was a direct replacement. This 22Si unit produces 150 amps. But then on the same page, three more Delco units were listed as Upgrade Options, a 24Si 160 amp model part #8600310, a 28Si 200amp model part #8600313, and a 170 amp model part #8600126. Has anybody had any experience with these? I have sent an email to Delco's technical service department to ask for clarification, but don't expect to hear back until after the holidays.

    There are a couple of guys on Ebay which occasionally offer "new" 27Si units, and the photos always look great. But when I read the fine print, I'm not so sure. And after I endured the deception from the SS member in Pennsylvania, I am a little gunshy to say the least. I would rather continue to spend my daughter's inheritance and have new units if possible. And I like the fact that the new Delco units are rated for higher amp output.

    Thanks in advance for comments.

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    4 Star General cucvrus's Avatar
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    You can have brand new alternators built for the truck. You can also send the used dirty alternators and have the cases bead blasted and rebuilt and they would look like day 1. I have mine rebuilt functional or for pretty all the time. Most times I opt for functional. Like I said many times there is a lot more to rebuilding an alternator and starter then just putting a few new parts inside. I watched the process during an open house. Sure you can make them work but to do it right it takes special equipment. Only time I ever ruined alternators after my first rebuild was from MUD. Severe off-roading is hard on alternators and starters.
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    I am patiently waiting for the 27SI alts to check out. When they do I'm switching my mounts over to the ambulance style of mounts so that I can run readily available Leece Neville alternators. Most folks try to steer away from anything M1010 as far as charging system but the "Plan B" mods done to my ambulance have been such a success, I'd like to switch my M1008 over. Not exactly what you wanted to here but that's my plan.

    I think rebuilding might be the ticket if you have a rebuilder that will work with you. Once the cases are blasted, get them clear powder coated.
    1986 M1008
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    I'd be hesitant to go with an alternator rated for that much current. As soon as that thing flashes the rotor after startup it would be belt squealing city trying to transmit a lot of horsepower on vee belts.

    You can get brand new bearings, brand new stator, brand new diodes, voltage regulator and more for those 27SI's you have. About the only part that isn't easily found is the rotor. If you can clean the rotor up a bit (carefully) and it isn't shorted I'd probably go the route of a full rebuild kit with a new stator winding. Should look like new after that.

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    Quote Originally Posted by Chaski View Post
    I'd be hesitant to go with an alternator rated for that much current. As soon as that thing flashes the rotor after startup it would be belt squealing city trying to transmit a lot of horsepower on vee belts.

    You can get brand new bearings, brand new stator, brand new diodes, voltage regulator and more for those 27SI's you have. About the only part that isn't easily found is the rotor. If you can clean the rotor up a bit (carefully) and it isn't shorted I'd probably go the route of a full rebuild kit with a new stator winding. Should look like new after that.
    OK I believe I will attempt to rebuild these 2 junk alternators I got from Pennsylvania. Any ideas on how to clean the stator and rotor?

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    I don't see were it shows those Alt. you listed to be isolated ground?
    You might use one but the other Gen2 will have to be modified.

    I agree any Alt can be rebuilt to zero time tolerances no matter the look or
    Condition it's in.
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    I'd pitch the stator in the trash and buy new ones.

    As for the rotor, maybe a light media blasting with walnut shells then a coat of glyptal paint? I'd be sure to check with a meter if the rotor winding is shorted to the rotor itself first.

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    Thanks for all the posts. I opened one of the cases and quickly came to the conclusion that I didn't want to tackle the job. Couldn't figure out how to get the rotor out of the front bearing anyway.

    So........ I am looking for a source for brand new Delco 27Si isolated ground alternators. Any leads will be appreciated.

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    Be careful abrasive blasting anything but the case, you may cause a failure.

    If the slip rings on the rotor are bad, they can be replaced. The stator can't be tested with an ohm meter because of the way it's wound. The stator either works or it doesn't. Unless there is physical damage to the stator, it's probably OK.

    The new 27SI replacements are not isolated ground. However they use the same rectifiers as the original alternators. I put together a kit for a member to replace the rectifier insulators and B- stud, these could be used to convert an alternator to isolated ground. You will need to drill a hole and add insulators and a B- stud/terminal to the rectifier. There is also a boss in the alternator where the negative heat sink contacts the case that needs to be milled down to allow the insulator to be installed.
    Ray


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    CUCV Alternator Rebuild Thread:
    http://www.steelsoldiers.com/showthr...rnator-Rebuild

    CUCV Alternator Parts Kit:
    http://www.steelsoldiers.com/showthr...or-p-n-1105500

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    Terracoma (12-27-2018)

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    Quote Originally Posted by Tow4 View Post
    Be careful abrasive blasting anything but the case, you may cause a failure.

    If the slip rings on the rotor are bad, they can be replaced. The stator can't be tested with an ohm meter because of the way it's wound. The stator either works or it doesn't. Unless there is physical damage to the stator, it's probably OK.

    The new 27SI replacements are not isolated ground. However they use the same rectifiers as the original alternators. I put together a kit for a member to replace the rectifier insulators and B- stud, these could be used to convert an alternator to isolated ground. You will need to drill a hole and add insulators and a B- stud/terminal to the rectifier. There is also a boss in the alternator where the negative heat sink contacts the case that needs to be milled down to allow the insulator to be installed.
    Thanks Tow, but I am looking for a source for 2 new 27Si isolated ground units. Cash in hand.

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