Since i put a dellorto on my a12 + auto it wont change to third till like 80-90 k's so im stuck in 2nd till there is no one in front of me causing bad economy. I dont want to spend too much money to fix the problem as im planing to put my SR in as soon as i can afford it.

Can you just buy manual valve bodies or is it like a custom thing?

Can u do it without removing the box?

there is a vacuum line that runs from the intake manifold to the vacuum modulator on the rear of the trans, if you disconnected it, or it has a hole in it the trans won't shift.
figure out why it isn't hooked up, rehook it up and it should shift much better.
most RWD Nissan transmissions are very similar to Ford's C4 trans, both in construction and operation. any good trans guy should be able to advise you further.

There is not enough vaccume because of the dellortos, causing it not to shift properly yes a more sensative vaccume modulator would work but I read all i can find about the jatco a12 auto and even if i put a more sensative modulator on its still not going to shift when I want, so Im going to manualize it.

Does anyone on here know how to?

You will need to remove the modualtor & block off the govenor circuit. There is also mods to do in the valve body. leave it to the pros. Because you now have a minifold tube per cylinder you can only take vacume from 1 cylinder so thats probably not enough. if you can some how get vacume from all cylinders it might make a differance. Thats the only logical explanation i can think of. Something i did on a turbo 400 in a ferari once was put a restrictor in the vacume hose because it was getting too much vacume. There is heaps of other things it could be if you want any help PM me.

I have the vaccume tree hooked up to two cylinders but your right its not enugh vaccume.

But this can be over come by manualising the valve body meaining there will be no need for the vaccume modulator.

So if I pull the pan off the tranny and pull the valve body out will an auto place be able to modify it for me (to save on labour costs) or will i have to take the whole car down??

Check out some FIAT sites, I have twin dellortos and virtually no cacuum for my brake booster.
Some yank cars had similar problems and use an electrical pump to create vacuum.
Good luck

I dont want to fix the vaccume problem Rather I WANT TO MANUALIZE MY AUTO THATS ALL IM ASKIN ABOUT the autos suck (ie they change gears at the wrong times) i cant be bothered changing the box to a manual if i was going to do that I would put my SR engine and box in if i can manualize the box cheeply I will. any advice on MANUALIZING AUTOS would be helpful thanks.

It would be cheaper to just put a manual in. Your going to have to have the auto out anyway to get it manualized so why not just get a $50 4speed and a pedal box + clutch $90 brand new or find a semi decent used one that someone is just throwing away and bolt her up. Much less hassle and probably cheaper.

So I do have to pull out the box to manualize it thanks for clearing this up Freak (it was a question in my first post) so obviously its going to be expensive so i proably wont do it then.

That sux cause i put the dellorto on because the standard carb was rooted now i got to spend even more time and money to get it to drive normaly A12 AUTO'S SUCK (actually all autos suck) looks like its time to transplant the SR from my other car into the beast no more SLOW ASS 1200 FOR ME!!!!!!!!!!!!!!!!!DAM AUTO'S

The following applies to the 3N71B transmision & was gleaned from my B210 factory manual. If the 1200 trans is the same model [& i suspect that it is] then it is relevant

Manualising the transmision involves making some adjustments to the govornor, modulator & gear selection control circuits on the trans. ALL of these parts seem to be accessable with the trans still in the car, even if it means pulling the extention housing.
The valve body assembly is accessable by pulling the pan & it can then be removed entirely from underneath if necessary.

A clever auto trasns bloke will be able to give you some sort of answer, & maybee even an estimate if he can get a look at your workshop manual first as the factory book is extremely comprehensive.
Removal of the trans should only be necessary if you need to overhaul the mechanical parts of the driveline within the transmision case itself.

Another alternative is to change manifolds & run one DelOrto instead. When correctly tuned, it will likely run better vacuum figures & the trans will work better, but i suspect that one carb doesn't provide the right image in the engine bay for most people.