Interesting T/A Info from the ALFA Montreal Site

[montelatici]

"If the slope of the TA characteristic is correct (i.e., the range of plunger extension from 20 to 100 deg C is the full 8 mm), the Spica TA can still be used even if the plunger extension has a small offset from spec. The cam centring screw in the Montreal pump is a standard 0.7 mm pitch cyl-head M4 one, 12 mm long, with a compression spring on the shank to prevent the setting being disturbed by vibration. Because of the spring, the available adjustment range is about 6 mm, or 8.5 full turns. The Spica designer arranged that when adjusted for a nominal TA the screw is nicely positioned with about 5 mm of thread engaged.

To accommodate a TA with a positive offset (excessive plunger extension), a shim can be mounted under the actuator flange to bring it within specification and the cam centring screw adjusted in the normal way. If a shorter screw is used instead, some turns should be clipped from the compression spring to allow the screw to be inserted further.

For a TA that has a negative offset, a longer cam centring screw can be fitted if the 12 mm one would have too few threads engaged. If this is done the spring should be opened up a little to ensure that it is still under compression. An alternative solution is to correct the TA itself by gently crushing the bulb, or inserting a tuning screw into it, until the plunger projection meets spec. Since the TA plunger has a diameter of about 4 mm it would not appear to be very difficult to add an adjustable screw extension to it but I have never heard of this being done.

If only a fixed length dummy TA is available for set-up, it can be used to set the pump gap and then the cam centring screw readjusted (at 0.7 mm per turn) to compensate for the offset of the real TA before it is installed. If an adjustable dummy TA is available (which is preferable) it can be set to take account of the offset before being used for set-up.

One result of a negative offset is that the lower limit of the range of temperature which can be accommodated will be raised. With a 2 mm offset the plunger will disappear inside the cylinder at about -10 deg C, as against -30 deg C for a nominal TA or -20 deg C for one at the specified tolerance limit. Not an issue for Florida residents but certainly a consideration for Montreal owners who may use their cars at Alpine winter resorts. "