what water pump is on the car, stock cast iron or an aftermarket alloy?
some of the aftermarket water pumps do not have the internal bypass pathway machined, this combined with a heater control valve may cause zero coolant flow until the T-stat opens
if there's no internal bypass in the water pump, or if the bypass is deliberately eliminated/blocked some other way the correct T-stat is a mute point
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.