Generator to alternator conversion. Need more amps.

[Meee]

Hi, I have Thiokol Imp 1404 with a generator and want to switch it out for an alternator. Anyone know which alternator would bolt in with minimal alteration. The correct pully and belt sizes would sure be helpful, as well. And any related advice would be appreciated. Thank you in advance.

 

[cloudcap]

I just finished upgrading the alternator in my Imp. From what I read most any 10si alternator would work and I went with this one from Amazon. Be sure and buy the pigtail and boot too.

Mounting the alternator was fairly easy. I had to drill out the holes on the new alternator (I think it was a 7/16" bit, but you should verify this) in order to reuse the original bolt. I stacked a bunch of washers to account for the more narrow mounting "ear" on the new alternator. My prose probably don't make much sense, but you'll figure it out when you compare the two units. I also needed to go to a smaller fan belt. At the end of the day it all fit w/in the existing alternator pocket on the doghouse.

I was able to reuse most of the original wiring. The original charging lead goes straight to the ammeter and I used it as-is. For the battery and sense leads you can reuse the wires that used to go to the regulator (which you should remove) in the engine compartment near the dash. Connect the pigtail to the wires at the alternator, pull the regulator, and then reconnect the remaining regulator wires (two from the alternator and two to the dash). I think the sense lead was patched straight through and I ended up having to put a diode in the battery lead. My Thiokol wiring diagram showed the sense lead connecting to the ammeter, but it actually landed on the starter. Since I was reusing the existing wiring (I'm lazy...) I left it on the starter and it has worked just fine.

The trickiest part was the diode. Even though I'm an electrical engineer I get confused on which way to install it. Absent the diode (or if it is backwards) the engine won't stop when you turn off the ignition -- the alternator keep powering the ignition even when the key is off. If the diode is in properly then the engine turns off when it should. You've got a 50/50 chance of getting it right the first time -- I managed not to.

I did the upgrade last fall and it has worked fine all season. It has the added benefit of putting out less noise on the wire, so my intercom system now only has a pleasant background hum vs. the earlier annoying whine.

Good luck -- this was a relatively easy upgrade and I've been quite happy with the result.

Ron

 

[nikos]

The Thiokol Imp 1404.

 

[Meee]

Hi, thank you very much. I ordered the Alternator. So do you have the number for the correct diode? I ordered a variety pack of diodes when i put in my digital tach so maybe already have it.

 

[cloudcap]

Pretty much any random diode will do. It should be rated for an amp or two, but beyond that it doesn't really matter. I put a couple in parallel just to make sure they had sufficient capacity. I put push-on connectors on either end of the diode to make it easier to install, so if you do this and you burn one out (for any reason) then it is trivial to swap in another one.

 

[mikemikelle]

Hey Meee,

Seen your Imp on Youtube before. Can you post some more pictures of your cool paint job.

Very unique!!

 

[JimVT]

you can back that in a snow bank if you don't want seen

 

[Meee]

Here's a couple angles. Someone smarter than me knows how to rotate the one on it's side.

 

[PJL]

Very nice looking Imp.

 

[mtncrawler]

Instead of a diode you can put an idiot light in. Will do the same thing but also indicate if your charging system has failed or ignition is left on when the engine is not running.

 

[Meee]

Well darn it, that alternator doesn't fit. It bolts in but is back 2"-3" inches and the belt doesn't line up with the water pump pulley and fan pulley. My Imp is an early one, #535 so I'm guessing 64ish. Back to the drawing board. Now got to put it all back until I can figure it out.

 

[MuskegRuner]

That's what the washers are for you put them between the motor and the alternator to get the proper spacing. I use a pipe that will go over the bolt and cut to length

 

[cloudcap]

Well that's disappointing!

If you haven't put everything back together yet, could you post photos of the old alternator and the new alternator (as they're installed on your engine)? This was an easy swap for me and I know a lot of other Thiokol owners have put 10si alternators in their cats, so I want to claim that this ought to be doable. I can't imaging how your original alternator could have been installed such that the new one is misaligned by 2" to 3". If you're willing/able to take some photos then it would be nice to get a visual.

Thanks

Ron

 

[Meee]

First my old is not an alternator, it is a generator just so we are on the same page. I went out and hung the new alternator and looked closer at the off set. So then I reordered the alternator si10 with a double pulley, which looks like I'll need to use the outer pulley to match alignment with the other pulleys.

 

[Jim_S]

First my old is not an alternator, it is a generator just so we are on the same page. I went out and hung the new alternator and looked closer at the off set. So then I reordered the alternator si10 with a double pulley, which looks like I'll need to use the outer pulley to match alignment with the other pulleys.

Are the holes in the generator bracket to mount to the engine block symmetrical or offset? If offset you might gain an inch or two by reversing the bracket.

Does the alternator have one long mounting tab or two short ones? If two you could use all thread rod to put the front alternator tab outside of the mounting bracket.

Jim

 

[Meee]

I put it back together because I'm taking it on trip Friday and the new new alternator won't be here until the following Monday. I did pull the bracket and of course it wasn't symmetrical and would have been upside down and would make it to low. I'm confident the new double pulley will work great. I took a couple pics. They seemed good on my phone, don't know if they show much now. Thanks for the help. This was great learning experience.