Join Date: Jan 2003
Location: Rapid City SD, Black Hills of South Dakota
Making a Dummy Thermostatic Actuator
If you have a SPICA car and want to tune it youself, a dummy T/A is an important tool. According to Alfa tech, the ONLY way to correctly set the pump gap is with a dummy T/A set to the correct length for your "T" model pump. I know some people use the actual TA to set the pump gap, but that is incorrect and difficult. Even if the T/A is extending the spec amount, pushing it in and taking it out to adjust the internal screw puts wear on the relatively fragile pipe.
In addition, if you're T/A leaks and no longer extends to the required length, your dummy T/A can be installed until you can get a serviceable replacement. Of course, you'd need to leave the top part of the T/A in the intake manifold coolant passage (or make a simple blanking plate).
If using a T/A as a temporary replacement, the engine may be slightly harder to start when cold (due to the lack of enrichment), but hot starting won't be affected (where enrichment isn't needed). If really in a bind and it's cold, you can always unclip the front of the SPICA air box and spray some ether Starting Fluid to get an initial start, then warm the engine before driving off.
At any rate, making a dummy T/A out of stock hardware is very easy.
Take a 1/4" x 3" long bolt (carriage bolts are nice 'cause they have a smooth top), two nuts, and a 3/4" OD washer. Assemble as shown and you have a dummy T/A. In setting the length, measure from the bottom of the washer to the tip of the bolt. Set at 27mm for pumps T237/1 thru T261 (1969-1976 [CA]) and 29mm for pumps T260/1 thru T265 (1976 [49 state] - 1981).
If you're willing to do a little more grinding or filing, then you can make it "slip-in" as described in the photos below. This mod will keep you from having to remove the screws each time to access the adjustment screw.
Of course, you can just push down fully on the dummy TA and not use the screws, then take a pump gap measurement and repeat as necessary. However, I'd recommend that you use the screws on the final check just to make sure the dummy is seated completely.
Here's a few pix. The last picture is of a factory tool. Note the hollow center to allow a screwdriver to be inserted and the pump gap adjusted without having to remove the TA. A makeshift dummy TA will have to be withdrawn each time to adjust the internal screw. However, with the rounded top of a carriage bolt, you can just press it down and hold it while taking a pump gap measurement.
Last edited by Roadtrip; 08-03-2004 at 09:08 AM.