Draw vacuum from both runners if you can. To stop the fluctuations in the guage, simply squeeze the line to restrict the flow of air. Use a fishtank air line clamp if you have one. Squeeze the line just enough to dampen out the pulses so that the guage reads smoothly.

It sounds like the adjustable unit is the way to go, but i highly recomend that you buy a factory manual & have a good read up on the parts that tell you what you should expect from this trans. It will also tell you how to fit the modulator.
Like I keep on saying, the manual should be the FIRST piece of performance equipment that one should get. It saves so much angst & grief.

I got a factory manual chassi, body and an engine one but it covers only the 3 and 4 speed manuals (never knew there was a 3 speed manual) will go to the book store tomorow to see if a seperate auto book is available, thanks dodgeman

and thanks for the restriction tip on the vacuum hose.

I don't have a factory 1200 manual, & the aftermarket ones i have don't cover the autos. There was a Jatco trans in the '69 & '70 Datsun 1000's, but my factory manuals are for '67 models. I have another B10 manual coming, so perhaps this one will cover it.

The only comprehensive coverage i have is in my factory 120Y manual & it is a VERY good book to have, particularly if this is the same model of trans.

How do I identify my box? where are the markings/ numbers?

There is a guy in vic called Phill Soderstrum.
He is the power glide king of australia. He can manualise any valve body you want. But if you manualise the valve body you will get harsh shifts. You will have to ring TCE there a torque convertor company & ask them how to get on to him. 03 9879 8455. they send converetors all over australia so a valve body wont be a drama. You DONT have to pull the auto out to do the job but to do it properly you should reco the trans aswell. I think you will get more out of a manual gear box & more fun and cheaper. But theres nothing wrong with being differant. good luck if you have any dramas PM me
P.S I think phills a bit of a grump as he probably should be retired but drag racers wont let him. He is the best in the buisness.

Cheers for that additional info 1200coupe but its just too expensive.

Dodgeman I got a book that covers the same trans as yours 3N71B for $5 your right its a good book although it dosent tell were the markings to identify the trans Can anyone help with that?

Something you might like to try is putting an extra washer under the modulator.
This will hold it out from the box a little further and therefore reduce the neede seating pressure. Similar to what will happen when you using the adjustable modulator, but will cost about 10cents for the extra fibre washer.

just go get a alternator off a nissan navara with a vacuum pump and chuck it on should fix the problem.

Cheers MLS will try this if there is not enough adjustment on the adjustable one (already bought it today so I may aswell use it)

Kegs with this navara vacuum pump does it create vacuume at idol and no vacuume at W.O.T. cause if it creates vacume all the time and more vacuume at more revs then I dont think it would work because i was looking on e bay and seen vacume pumps for cars some for like $5 and those vacuume canister things but I dont think it would work.

what does the vacuum pump actualy do on a navara (ie what does it create vacuume for)?


Also started reading about the autos in the 120y book and autos are a work of art very complex in opperation still would rather a manual any day though.

I would try something along the lines of what has been said; Take off the manifold and tap each manifold runner and then use standard pipe and fitting from a plumbing or hose/fitting shop and bridge them. Have an output to the transmission line somewhere on that bridge tube. Easy and should be less then $20 in parts. Be sure to have the manifold cleaned out very well after the tapping, you don't want any metal flakes from the manifold going into the engine.