I am debating with myself over fitting a 5 speed or keeping my auto and fitting a 2500rpm stall converter.
I will be using it with a A15 with about 90hp and am led to believe that the auto boxes are rather strong.
I am concerned over the first gear ratio eing so tall (like 60kmph at 5500rpm) and because of that, take off is very sloooooow! Thats why I am thinking about the 2500rpm stall, but am worried it will hurt the box.
Also I will be using a 54/86 cam so there won't be much go before 3000rpm

Ive heard with a modified cam you will have trouble with vacuum which the auto relies on to shift. As for shifting you can alter that through the bands.

yeah I was going to see how it goes and if I had trouble I was going to use an adjustable vacuum modulator, also with the twin side draught intake manifold I will drill a hole in each runner and tap a thread into the holes and fit some brass fittings to run vacuum to the transmission from each cylinder. would that make things a bit more compliant?

Based on my experience of just reciently swapping out the auto for a 60 series 5 speed, don't even think of the auto for performance.

With the 5 speed (4 speed would be good too) the responsiveness of the car is magnitudes better.

You can get so much more performance with the manual tranny as you are in control of what happens. The auto just wants to get in hi gear as soon as possible. Also won't drop back into 1st very well either.

An adjustable vacuum modulator helps (mine was cranked all the way up for highest shift points) but you still have an old technology auto tranny that just does not do justice to the small engines.

On the fuel economy front, with the auto in the car 26 MPG was about the best I got in mixed driving. With the 5 speed I'm getting 35 MPG while driving harder than with the auto.

All in all, the manuals are much more satisfying than the autos.

Gary

I

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Lightened flywheel? In an auto?
I'm afraid they don't use one. They have a stamped steel plate with a ring gear on it & the torque converter is attached to this.

There is more than enough mass in the torque converter to substitute for a flywheel, so there is really not much that can be done here without using a smaller torque converter & I suspect that these might be a bit hard to find for our Datsuns, ... unfortunately.

Dodgeman I thought that the three speed auto was the same or very similar to the VL commodore 3 speed auto box with the overdrive bolted on the back? if so I know that dominator make stall converters for them.
Stall converters work by allowing the engine to rev up before drive is initiated, by doing this it can offer more performance from a naturally aspirated engine which doesn't make much power till around 2500-3000rpm, this makes launches a fair bit more hasty when compared to the stock converter....almost reminds me of trying to pull out onto a high way in 2nd gear from a complete stop