Which alternator?

[Mudviper]

What alternator is everyone running on their 12v conversions? I currently have a prestolite alternator on mine and it is putting out about 14.5v. According to Omix, that is to high of a voltage output to run their distributor and could be why I keep blowing modules.

[Ryan_M]

A Delco 10SI is a popular one to use. Worked well for me on my previous 12V conversion.

[aboyandhisdog]

Mud, does your coil have an internal resistor or are you using an external resistor?  If you're not using an external resistor, you have to verify that your coil has one built in.  If there isn't a resistor in the mix, this could be your problem.  My old OE coli used the external resistor on the firewall, but when I bought a new "flame thrower" coil, the resistor was built in so I bypassed the one on the firewall.  Just something to check out.

My alternator came from Napa.  It is a Delco 3-wire and I'm not sure of the part #.  As I recall it is 65 amps.  The Napa guys should be able to set you up with the right one.  The one Ryan mentioned is usually the go-to alternator and I believe is the one that KW includes in their conversion kits.

[Mudviper]

Mud, does your coil have an internal resistor or are you using an external resistor?� If you're not using an external resistor, you have to verify that your coil has one built in.� If there isn't a resistor in the mix, this could be your problem.� My old OE coli used the external resistor on the firewall, but when I bought a new "flame thrower" coil, the resistor was built in so I bypassed the one on the firewall.� Just something to check out.

My alternator came from Napa.� It is a Delco 3-wire and I'm not sure of the part #.� As I recall it is 65 amps.� The Napa guys should be able to set you up with the right one.� The one Ryan mentioned is usually the go-to alternator and I believe is the one that KW includes in their conversion kits.

I am using a Napa coil with an internal resistor. I double checked the coil before I installed it with a ohm meter to verify it had a resistor in it. I may hit the junkyards this weekend to see if I can find another alternator to try out that doesn't put out so much charge. I live in Flint Mi, so there is a good supply of GM vehicles around..lol.

[squidtone]

You may want to consider a 12si alternator. They are a tiny bit more modern than 10si, can generate more power, and cool themselves better. There is a Lester number you can look for if you shop at a parts store. Or, you can look in the boneyards for some early 80's cars that have either a 10si or 12si and most feature the better "3-wire" type connection. From what I understand, a 3 wire starts charging at a lower RPM, and you can incorporate an "idiot" light which is really nice to have to indicate whether you are charging or not.  The list below is something I found on the 'net that kind of tells you what cars to look for. The "Lester" number (7137 for 10si, 7294 for 12si)is just a industry wide used parts number used. I believe you don't have to worry about "clocking" when you buy...you can simply back out case screws and rotate (or "clock") the case to best suit your needs.

10SI Alternator (63 amp) 
3:00 321-39 / 7127-3 78 Chevy Camaro 350 with AC
6:00 321-135 / 7127-6 No application was found.(** See note below)
9:00 321-41 / 7127-9 79 Buick Regal 4.9L (301W) with AC
12:00 321-43 / 7127-12 77 Pontiac Grand Prix 5.7L (350R) with AC and HBL
12SI Alternator (94 amp)
3:00 321-266 / 7294-3 84 Chevy Camaro HiPo 5.0L (305G) 94amp
9:00 321-269 / 7294-9 85 Buick Riviera 5.0L (307 engine) with HD options and AC
12:00 none / 7294-12 NO AC DELCO part number or application
12SI Alternator (78 amp)
3:00 321-247 or 321-357 / 7278-3 85 Pontiac Firebird 5.0L (305H) no AC, HBL only.
9:00 321-244 / 7278-9 85 Oldsmobile Cutlass Supreme 5.0L

Good luck!!

Dave

[Mudviper]

You may want to consider a 12si alternator. They are a tiny bit more modern than 10si, can generate more power, and cool themselves better. There is a Lester number you can look for if you shop at a parts store. Or, you can look in the boneyards for some early 80's cars that have either a 10si or 12si and most feature the better "3-wire" type connection. From what I understand, a 3 wire starts charging at a lower RPM, and you can incorporate an "idiot" light which is really nice to have to indicate whether you are charging or not.� The list below is something I found on the 'net that kind of tells you what cars to look for. The "Lester" number (7137 for 10si, 7294 for 12si)is just a industry wide used parts number used. I believe you don't have to worry about "clocking" when you buy...you can simply back out case screws and rotate (or "clock") the case to best suit your needs.

10SI Alternator (63 amp)�
3:00 321-39 / 7127-3 78 Chevy Camaro 350 with AC
6:00 321-135 / 7127-6 No application was found.(** See note below)
9:00 321-41 / 7127-9 79 Buick Regal 4.9L (301W) with AC
12:00 321-43 / 7127-12 77 Pontiac Grand Prix 5.7L (350R) with AC and HBL
12SI Alternator (94 amp)
3:00 321-266 / 7294-3 84 Chevy Camaro HiPo 5.0L (305G) 94amp
9:00 321-269 / 7294-9 85 Buick Riviera 5.0L (307 engine) with HD options and AC
12:00 none / 7294-12 NO AC DELCO part number or application
12SI Alternator (78 amp)
3:00 321-247 or 321-357 / 7278-3 85 Pontiac Firebird 5.0L (305H) no AC, HBL only.
9:00 321-244 / 7278-9 85 Oldsmobile Cutlass Supreme 5.0L

Good luck!!

Dave

Thanks Dave (squidtone), that some good information. My CJ7 actually has a 10SI alternator on it, but is set up as a one wire system. May have to take it off CJ and put in on the Willys and see what it does.

[JimVillers]

I would use a "mini"-Denso alternator that is used on tractors and other small vehicles.  It is small and easy to mount.  It produces 45-50 amps or so which is more than is required.  I make a conversion kit for a 190SL Mercedes that uses this alternator and it works very well in the older cars that do not need a larger electrical source.  They are also used on many race cars. They come in one or three wire version. 

At my source, they are less that $100 (I use the AHAND0197):
http://www.psep.biz/store/denso_100211-1640_thru_128000-0070_alternators_and_starters_by_oem_.htm