Alternator confusion

[mrk5]

I was going to swap in a new alternator this weekend but the new one wasn't physically the same size. It's in the 89 crewcab, R3500 350TBI motor. It should be a 12si alternator. It looks like a 12si.

The alternator I ordered was a Powermaster 12si but I didn't order the one listed specifically for my truck because the application specific alternator had a v-belt pulley and I need the 5-groove pulley. So I found another 12si alternator that came with the 6-groove pulley that will work for the 5-groove. I think the one I got is what they consider "hot rod" line probably intended for a car.

The mounting holes on the new and existing alternator are at 12 and 6 o'clock positions, straight across from each other. The new alternator is 1" to 2" shorter between the mounting holes.

The other thing I notice is the alternator in the truck has an "open" fan. Most pictures I see of the 12si shows the "covered" fan.

So do cars come with physically smaller 12si alternators? Do I not have a 12si?

 

[mrk5]

This is probably the best picture I have.

 

[mrk5]

Okay, I think I figured it out. Found dimensions for the 12si:

Mine is definitely more than 6.6" between mounting holes.

Found this drawing for the CS144:

I'm pretty sure I have the CS144.

 

[mrk5]

Okay did some looking and measuring. Dimensions don't match cs144 either. I'm pretty sure it's a 22si.

Upon closer inspection I can see a spacer between the bottom ears and they used a nut as a spacer between the rear most ear and the engine block. I'm pretty sure I can tell the top bracket has been bent to accommodate the taller alternator. Which also explains why there is no adjustment left in the bracket to tighten the belt.

If the 22si is supposed to be an upgrade, it's not enough to keep up with electric fan and headlights at idle.

 

[Big Ray]

the one in your truck looks like the one that was in my 86...I have an 89 that looks like the cs144


that's all I got

thinking of an upgrade for my 90 6.2 'burb when funds allow.

 

[Big Ray]

fwiw, the Pontiac Transport unit is supposedly a cheap upgrade for our trucks...140 amps stock iirc...

 

[Fordum]

I suspect that the answer to your questions is somewhere on this site......
http://alternatorparts.com/index.htm#gm-type
Just not sure where....

They seem to make good stuff, pricey though. If anyone would know what you have I think it would be them.

Might drop them an E-mail.

 

[kgblazerfive]

Scott,
Yours looks like the one i have on the burb. Comes from a 78-79 caprice cop car. Highest amp one in that configuration.

As long as what ever you buy has two bolts you should be able to make it fit.

 

[kgblazerfive]

and...... you need a bigger air cleaner. At least from the picture it would be recommend .

 

[mrk5]

Haha. I knew someone would comment. That is an old pic; the dumb PO had that on there. I have a factory setup on there now.

 

[dyeager535]

The plug is going to at least get you closer.

The kidney shaped plug (with up to 4 wires) AFAIK was only used on the CS130 and CS144.

The two wire plugs (rectangle connector) were only used on the SI series.

 

[mrk5]

It is a 2 wire plug.

 

[dyeager535]

Definitely not the CS series then. I've never seen any alternator with those dual ears, didn't know they existed.

Time to pull the trigger on a CS144.

 

[mrk5]

I would go that route but I already have a Powermaster 12si I thought was going to be straight swap.

I'm on my way now to the pick n pull to find a good set of brackets.

 

[kgblazerfive]

build the brackets

and you posted the pic, so it is your set up, none of this blaming the PO stuff