I'm still running my stock alt and divorced voltage regulator. It seems I'm in need for an upgrade. Anybody mounted and wired a larger one. How big? Was it difficult.? Did you have to replace heavier gauge wires in the loom or can you still run with the same wiring?

Get your existing ALT rebuilt to your spec. What do you need? More amps?

Yup. I've been told that the EFI that I'm going to install requires a bit more juice than my current stock setup will deliver. Obviously originality is not a concern. Everybody I've talked to has gone the " bigger must be better" route and gone with 140a alt. Don't think I need all that but maybe an 80a would suffice. Just wondering if anyone else had made the jump.

I put a bigger one on my 69. Don't remember specifics. Offhand I think it was a 12si (the one with the plastic fan), around 90 Amp, made for an 80's Camaro. Don't know if I HAD to, but I replaced some of the wiring with bigger gauge wires, since I was rewiring everything anyway. Moved the junction/splice from on top of the engine to a junction block on the firewall.

If you need, I can dig out the specifics on which alternator it was.

Power master recommends a bigger wire based on the output amps of the alt and distance. There are other places that also recommend the same. I am also doing the same thing Lee stated above by using a junction block and am running a 6 gauge from the Alt to the block. Take a look here. http://www.powermastermotorsports.com/charge_wires_a.html

If you are looking for an easy solution, and originality is not a concern, you can switch to a 1 wire alt. . Just pick the output (amps) you want, run the proper size wire to the battery, & your set. You can even leave the old regulator in place for a stock look. its what I did & it operates great.

I think I've settled on a 94a unit. I think it is a 12si version. Came on a 84 z28. I may mount an additional fuse block to run some of the new accessories from. Not exactly sure how I'll go about that but I'll figure it out. Thanks for the ideas.

A buddy gave me a couple spare 61amp units he had sitting around. Not sure if that's enough of a bump though. The new fuel pump runs a 20a fuse and if I add a pusher fan I hear those run off a 20-30amp fuse as well. Last thing I need is to be in traffic with the AC going and my pusher on trying to keep them things cool with my Walbro fuel pump feeding my new EFI and have everything crash and burn. Now that I see if written down I think I will definitely opt for the 94a even if I actually have to spend money on it.

the first link is for Chevys , I am not sure where the mounting points are on the Pontiac Alt. If they are at 12 and 6 O-clock then the Alt he lists for the long style water pump is the Alt you want. The wiring will be the same for the Pontiac. I have done this on my 69 Firebird, and my son's 68 Nova, they work great
this is the Alt from OReilly Auto parts, R111761A

http://www.chevelles.com/techref/ftecref14.html

Read through the different tech wright ups, very good info. I did the remote voltage sensing on my Firebird works good also, will be doing the brighter headlight relays in the near future

http://www.madelectrical.com/electrical-tech.shtml


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The three wire SI alternator is definitely the one to use, built in regulator that is easy to test and replace and simplifies the wiring. I have my sensing at the dash where my junction block is. I fed the junction block with a #8 wire then ran another # 8 to a second junction block at the rad support. You may as well go with the ford style starter relay while your at it as that is also a good place to connect accessories, the cable to the starter is only live when starting and keeps the start wire from the ignition switch away from heat, great for connecting a remote starter switch to as well. I found the junction block on the rad support great for hooking up the fans, head lights, horn and using to power a timing light, kept all the wires on the number one spark plug side of the car.

Looks good Al. I hope mine comes out as clean. I plan on more or less the same sort of thing. I was thinking about a #6 charge wire but probably could get away with a #8.

The CS130 type alt is better than the SI alt. It puts out more at idle

Some of the bigger alternators put out more juice at lower rpms but may run into trouble at high rpm. More mass spinning fast, the larger diameter the spinning parts the more force.

Bob, I don't think you need a large wire for charging, I just ran a 12 or 14 to the battery, not many amps when charging but a heavier wire to the terminal blocks that have high draw accessories feeding from them.

Yeah, I get that but the way i have it wired, in my head anyway, the battery charge and all equipment on the car will be run through that charge wire so it will have to be big enough to handle it. The original wire was 10gauge. That ran everything in stock configuration. Probably all the new stuff could be run through an 10 or 8ga. But put all that draw through the same wire feed from the alt...I think I'll go 6ga. I know it's overkill but my battery is in the trunk so that power has to travel a long way to keep it charged already and with all the additional draw, well I just don't want to take any chances.

Can't hurt going bigger, when it comes to carrying current, the bigger the better. Having the battery in the trunk would require a bit larger than if it's on the rad support.

My Batt. is in the trunk also. I have the Ford type starter sol. on my core support where the Batt. used to be. My Batt. cable from the trunk goes to one post on the Ford Sol. I run my charge wire from the Alt to that same post. I run a #6 cable from the Alt to the Sol. I like to be safe in case for some reason the Alt goes to full charge, it won't burn up the charge wire as fast.
Also the CS130 type alt is about the same in size, if not smaller than the SI type alt

I ended up buying the 94a 12si model. I would've gone the 130 route but there was an issue with the clocking. I also bought #8 wire for the charge wire. Was going with 6 but that stuff is crazy expensive and #8 is what they recommended anyways so it should be good. There's not that much draw on the system anyhow. I bought a 4 fuse block and a couple relays. Now I just have to muddle through the installation.

I have the SI alt on mine also, I did mine a long time ago before I knew about the 130's . When this one goes out I will be going to the 130. I did the 130 on my son's 68 Nova and it works great
I get my wire from the scraps from work is why I go as big a wire as I can. I know the wire costs a lot
Did you get enough relays to do the headlights, to make them brighter? I will be doing that next on mine after I finish the interior

I bought 3 relays, one double and one single. Most of the equipment I'm adding comes with it's own relay so I'll prob have a couple extras if I wanted to use them for the headlights. I really didn't want to run any additional wires around in the engine comp if I could help it. I wonder what gauge power wire you would run to each headlight from the relay?

You can use the original wire to the headlights from the relays. The wires from the dimmer switch control the two headlight relays, high beam turns one off and on, low beam turns the second one off and on. But you have full alternator voltage feeding the relays and then the headlights through the original wires. You aren't upping the amperage just supplying the headlights with full 14.7 volts. When stock, the headlight circuit starts at the main junction goes through the firewall junction blocks, to the headlight switch to the dimmer switch then to the headlights. Every junction and switch is a potential voltage drop. Mine was about 10 volts at the headlights, now it's 14.7 volts. The difference is surprising! I replaced the wires but it's not necessary, just cut the wires at the relays and have them control the relays and use the rest to power the lights.

So you eliminate the power wire from the dimmer switch and replace it with a direct power feed to the relays and use the dimmer switch wires to switch the relay power on and off. I suppose you can junction all four power feeds for the relays from the same power feed on the front of the radiator support. You basically end up with the same number of wires but the one power wire might be a gauge or two larger?

Yes, I think.
Say you install the headlight relays onto the rad support or the drivers fender, you can cut the high and low beam wires from the dimmer and use those to control the relays. Connect the rest of the wires that go to the headlights to the relay output terminal. The relay input terminal is connected to the power source from your alternator or, preferably, from a power junction block that is fed from the alternator via a larger gauge wire. You can also use that junction block to power relays for fans or other accessories. I have fusible links connecting the headlight wires to the relay just in case of a short to ground. You could use breakers if you wanted to, but some kind of wiring protection is needed.

I have one junction block on the firewall and one on the rad support fed with #8 wires from the alternator. The rad support junction has two wires going to two 30 amp breakers and on to the two cooling fan solenoids I have another wire going to a 20 amp breaker and on to the horn solenoid. I have two fusible links going to the high and low headlight relays. I also have another fusible link going somewhere else but forget where, and a couple of spare fusible links dead headed under the harness just in case they're needed.
I made a rough schematic , not as rough as the attached drawing, to help my fading memory, but it's away in the files.

It's really quite simple once you picture it in your head.

Hope that didn't confuse you with too much rambling.

Just finished up the 94amp 12si install. Good thing I did it when I did. The main power splice must've gotten really hot at some point because there was a lot of melted insulation of the wires right around it. Made its way through all the wrap and I think it was making contact with the intake manifold right next to the carb. Not good. Glad I caught it before the fire. Anyway I think it's all good now. Everything seems to be working like it should. Time will tell. Started the car and turned everything on and nothing was getting warm to my touch.
Next up is dropping the gas tank for the fuel pump install. Not looking forward to that.

Hey Bob, what kind of junction box is that you are using?

Can't remember the brand. I'm sure it's listed in my last summit order( I can get you the PN if you want). It's got the junction lug at the bottom and it powers 4 fused outlets if you want to run any other circuits off it. It's even got little LEDs to let you know it's a live circuit. Pretty easy to wire a fan or whatever off it. Plus it's already fused.

Interesting, I have never seen one like this and would be interested in the PN....Thanks

Bluebird, how did you run your charge wire to the battery? It doesn't look like the charge wire was connected to the side where the big cable comes from the starter relay back to the battery in the pic of the starter relay. Why wouldn't you connect it there if you didn't like in this example? Also, where exactly did you mount that starter relay? I can see that it is close to an inner fender, but which side?

Summit PN SUM-900375 $15

Ordy, That's the way I did mine, maybe just couldn't see it in the photos I posted. I have a terminal block on the firewall, from there I have a wire going to the starter relay on my fender lip. the wire is a red 8 gauge and the fusible link is a cream 12 gauge. I'll attach a photo that shows it clearer. The only wires I have attached to the battery are the POS and NEG battery cables.

Sorry,
I mounted the relay on the passenger side fender lip just aft of the battery. the fender brace is off in the photo as I was doing the wiring when I took the pics.

Here's a pic of some of the main wiring I cut out.

Excellent thread guys

Holy crap, that's even worse than mine was.

Yeah, scary huh?

Thank Robert!


Thanks Bluebird, yep just cant see the wire connected in the pic of the relay. BTW, where is your Batt located? I thought you put yours in the trunk? Just a curiosity type question, if you did put your Batt in the trunk, why have your starter relay on Pass side fender?

No, mines on the tray where it was stock, well right now it's on the floor of my garage but that's another story. I bought a new tray when I first rebuilt the engine and installed it where the old one was. I think that tray was to only replacement part I've purchased for my Firebird that actually fit. Robert has his in the trunk, I suppose if I raced I'd have to move it and install an outside shut off/cut out.

Thanks Al, I am not sure why I thought that, but it is all good! I am struggling on where to put my starter relay because mine is in the trunk and think that it might be better to put it on the firewall since I would only have to run one wire to the rear (Pos batt wire). Anyways, it is all good, I really like all the suggestions or input on options/ideas!!