How hard is it to convert a single field alternator to a dual field alternator? The reason I ask is because is most of the dual field alternators at the parts store have a completely different case and are probably off a later front wheel drive car. My alternator brackets/spacers don't work with the later case. I was lucky to find a old style square back at a parts store, but it went bad, and finding a replacement will be hard. All the single field alternators I've seen at the parts store have the smaller old style case. Could they be converted to work with the newer dual field regulator? I have a mallory hyfire VI so I don't think I could go back to the old style regulator.

I have not done it but I understand that you can take an insulated brush assy from either of the field terminals from any dual field alt & sub it in instead of the grounded brush assy on the earlier one in question.

so a couple of things.
The dual field alt are generally 60 amps, with the 89 full size cars having a dual field with 74 amps.

The single field max output is like 45 amps.

So take that into consideration.

If you are currently running a square back, I am confused on why your brackets don't work.

If you have a small block, I know generaly the swing arm is not long enough when you try to switch over. I found the 10 dollar GM chrome swing arm at the parts store (mr. gasket I think)gives you enough reach to make the square back work. You need to put some spacers behind it where it bolts into the block so it comes out far enough to hit the alt.

I think it would be far simpler to swap out back to the single field vr if you really plan on going to the round back setup.

Just take the single sensing wire(hot on key on) and tap that into the new vr. The out put line to the alt.

But I think I would work on finding the correct square back.

The new cheap re-pop single field voltage regulators are electronic, not points style. I wouldn't see a problem using one with an electronic ignition box. That way you could use either a single field alternator or a dual field with one field grounded.

Thanks guys. I exchanged my newer style squareback alternator for another newer style squareback alternator. It looks like this one may work. My previous new style squareback was notched by the alternator ear which did not let me rotate my alternator down low enough. I will try to exchange my old style squareback for another one before I try installing this one.

just need to drill couples of holes on housing blank space and install a brush and isolator there, removing the old grounded brush:

Thanks NachoRT74. My alternator is spaced out from the block farther than stock because I am using the BPE hidden a/c compressor brackets. Block clearance was fine, but the alternator ear was hitting the upper alternator bracket. I read your other post. Does Beck Arnley list a different part number for the hidden stator and the visible stator squarebacks? The brand I have uses the same part number for both types of alternators. 90% of the ones I've found are the hidden stator type which makes getting a warranty replacement hard.

Has anyone tried the powermaster retro alternators? http://www.powermastermotorsports.com/mopar.html They look nice and have a butterscotch stator. Are they good quality and rebuilt in the US?

this is the funny part on this... laters squarebacks were more on production. Earliers were just around 5-6 years. Then rest of 70s and all 80s used the later.

Beck/Arnley list diff PN for everyone... 4 PNs for them... 2 earliers and 2 laters, with 1 and with 2 grooves pulleys each one.

2 grooves pulley on lates is the 78 amps one.

AC Delco and Remy too, just that they don't list the lates 2 grooves alts.

some are also 65 amps

Thanks Natcho. I was to exchange my old style squareback for another old style squareback at the parts store on the other side of town. I installed it and it works great. I may try the hidden stator alternator later on. I had one in my old 440 and it never died. Thats good to know that Beck/Arnley lists a different number for the old style case. I will buy one of those next time.

there is also ORIGINAL roundbacks alts with dual prongs.

My knowledgement about is they began to be installed on lates 69s C bodies, being standart in all 70s

In fact those 69s have both provisions for dual prong or single prong ( grounded brush )

I did know I was already talked about the regular single field ( prong ) roundback to a dual with an easy job. This is a pic I already prepared long time ago:

( well on number three is really an original dual prong already factory made, like the one I did show above, but to get the idea of the final look )

then on lates 70s I think and all 71s where on this way.

( I can be some wrong on exactly dates when they appeared, but more less must be on that way )


Note, not anymore the grounded brush provision

I think this makes a total of 5 alternators changes allong lates 60s and all 80s, without ouput and pulley considerations, just about exterior looks and setup. Being more critical changes the 69-72 period

1-Roundback single prong
2-Roundback with both setup provisions ( single and double
3-Roundbacks double prong
4-Squarebacks with visible stator
5-Squarebacks with hidden stator ( wider housing and stator windings, also one diff brush isolator )

FYI - many times when an alt fails it is just a brush that has gone bad or finally worn out and they can be replaced (sometimes with the alt still mounted) and cost about $5.