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Alternator Swap

2816 Views 10 Replies 6 Participants Last post by  Graham

I have read a couple of these threads related to the replacement of the stock GT alternator with a GM one. However, I am looking to upgrade to a larger amp alt. Does anyone know of an easy modern day replacement alt. from another manufacturer or distributor such as NAPA or Canadian Tire. I am looking for something that bolts right in without a lot of re-wiring---- or am I just dreaming?
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Graham, According to my Clymer's for the 95 Camaro V-6 I'm putting in my GT, there are two basic types of alternators available from GM. Those that have the case halves riveted together are less than 100 amps and those that are bolted together are at least 100 amps. It is just a matter of getting one that will fit with the least amount of mods required to get them mounted. A trip to your local auto parts store should be able to cross reference the alternators to the one that will fit your requirements. HTH.
Alternator install

I have followed the advice of one of the threads and purchased a GM 65 amp Alt from NAPA, part number 13-4011B. The problem I see now is that the old alt had three wire connectors, and this new one only has two, see the pics attached.

Have I got the right one? If yes what is the wire configuration?


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i no its been posted how to wire that up correctly on a gt i just cant rember how it was done or were to look any one else have a idea???
Graham, check out this thread, http://www.opelgt.com/forums/showthread.php?t=248&highlight=alternator In post nos 5 is oldopelguys answer. Midway through is the part about the wiring. HTH, Jarrell
Great, thanks a lot , just what I needed.
New Alt-More Amps--Possible problems

I am putting this out as a seperate thread because it might get hidden at the end of my other threads. Here is my concern:

I have upgraded the old GT alt with a 35 amp output to a GM 65 amp output.

With this increased ampage do I run a greater risk of overloading the already fragile and old wireing which might cause a fire?

Should I be installing some in-line fuses? And if so where?


PS: so far the install/swap is going well, I am off to the wrecker today to find a new upper bracket.
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no ,no, nowhere and good luck finding the bracket
Graham, Check this link, http://www.opelgt.com/forums/showthread.php?t=248&page=3&pp=15&highlight=alternator, and my post #40, and you will see how I did mine. The upper bracket you will have to cut and drill out for the hole, but I've had no problems so far and it all works. I did later go back and added a terminal block and relays for High/low beams, fuel pump, and fog lights. I got the relays through http://www.madelectrical.com/index.shtml. A little pricey, but everything is included, wire, fusible links, connectors, heat shrink tubing. Local auto parts sell relays as well, cheaper. I didn't want to take a chance on melting down the fuse box. Jarrell
Graham said:
I am putting this out as a separate thread because it might get hidden at the end of my other threads.
Sorry Graham, but I am trying to have the threads MORE complete, rather than more split up, when they are related, and these are related. So I merged the threads (which I had done with the earlier ones). But thanks for using the correct forum.

As for wiring concerns, the bigger alternator only increases the number of amps it puts out when required to, NOT the draw. If the load is the same, the bigger alternator will simply do a better job at keeping up the voltage. In fact, I think if the battery voltage is kept at 14 volts by the higher output alternator rather than allowing it to be drawn down to a lower value (say 12 volts), the same "load" at the higher voltage will result in a lower amperage draw. And "amps" are what heats the wires, not voltage.

As for fuses (or circuit breakers), the standard ones are still a good idea. The most important one to add is a 40 Amp for the headlights circuits, which are otherwise "protected" (barely or not at all) by the main fusible link.

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Instal/Swap complete

Thanks to everyone at this site I was able to complete the swap over this morning. A quick test drive shows a healthy charge and all of the electrics working at once is a treat. To share some of my install concerns I was able to get an upper bracket from an 86 Dodge Diplomat. I had to cut off 1' then drill a new hole, a little bit of bending to clear the distributor, and it works like a charm.

Here are some final pics. Again thanks again.
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