over reading tach after spring tune up

[ShoulderMan]

Hello all

 I decided to get my lil A/C less 89 golf ready for the arizona heat. I replaced all the water hose lines cept for the one that goes from the resivor to the metal pipe (anyone know where to get one?) replaced the thermostat, and while doing that noticed that the water pump needed replacing, after that I figured if im in it this far, might as well replace the timing belt as well, then said what the hell, and swapped out the IP for the one from my 91 jetta. while I was putting everything back togeather, I noticed the transmission mount was broke (cause the transmission went way up in the air while I was tighting up nuts and bolts) So I replaced that and the front mount. I also had some new turbo injectors laying around so i installed thoes as well. with the new heat shields.   
    After reading hours on end, I found out how to time the engine (thank you vincewalden) and to my suprise, she fired up and didnt explode. 
oh yeah, I also replaced the alt. with the larger 90 amp one from the jetta, hooked it all up, made a homade alt bracket to keep it in place, and connected the 3 wires, big red to starter, red w/black stripe to green tach wire and blue to blue power wire.
 
So I start it up again, and the tach jumps up to 2500rpm,  if i feather the throttle just a tad, she jumps to 4K, and where 2k should be the needle burrys its self to the 6-oclock position,   where say 2500-3000 rpm should be it backs its self up to 4K
   
 I have not taken the alt. apart, but I have cleaned it up with electric moter cleaner checked all the connections, checked the search function but found nothing on this problem.    Ive read there is a pot I can adjust, but i dont know if theres enough adjusting for this large of a rpm jump, someone said maybe the pulley is too big/small, but why would the needle jump from 2k,4.5k, 8K (if it were to go that far on a diesel) then jump back to 4K all while continuiously opening the throttle.

Any thoughts on how to fix this, cause if i cant find out how, i guess Ill have to put the old alt back on for now

Also I notice that my injectors are leaking from the threads, fuel and bubbles,  is this a concern, or as I read, do i need to wate a few heat cycles before it seals its self.

hanks

-Ron

[Otis2]

If you want to use that 90 amp alternator, you'll have to de-solder a resistor from your tachometer's circuit board, and replace it with an adjustable one. 

Details of the process are in this thread from the FAQ:

http://www.vwdiesel.net/forum/index.php?topic=12589.0

[ShoulderMan]

Thank you