If you wanted to run your engine a bit cooler, either to richen up the AFR or reduce engine knock due to heat, you went out and bought a custom thermostat at a cost of about $80 with shipping as I did not once but twice got ripped off by a vendor of Corvetteforum.

I did this to find a 178 custom stat only allowed a maximum of 163 at highway speeds when used with a race radiator !

I was upset at this cost and not getting what it was supposed to be so I began studying the thermostat design and with the experience and knowledge of teammate Gary S, I began testing a method of modifying the stock thermostat and found for less then few dollars I could make the stock thermosat adjustable.

Review the process at :

Save money and modify stock stat

Here is my style of cooking on the stove, testing each shims thickness to opening temp.



Thus for a few bucks you now can adjust your stock termostat at a lower opening temperature.