Even tho it says it, I believe thermostat is not sticking and in a pan of hot water it never fails. What I have 292  Edelbrock dual quad manifold, Vacuum heated control. 170* high flow thermostat. 

The vacuum heater control valve on an Edelbrock manifold is closer to the thermostat than on a stock intake. I believe the extension on a vacuum valve hits or interferes with the action of the thermostat spring at times, It seem to be a problem when cold on first start-up more than after it has ran.

Has anyone else had this problem or do you see any reason to not remove or shorten the extension on the the heater valve which protrudes into the area of the the thermostat. The extension screws into the valve body. A non high flow is smaller in diameter at the spring but I've fought a cooling problem for years and it seems to be fixed and I don't really want to change the high flow back to standard.

Cooling fixes include: 5 blade fan, radiator shroud, plug in bypass with 1/8" hole, and smaller water pump pulley. Open for suggestions.. Thanks



56 Vic, B'Ville 200 MPH Club Member, So Cal.