I am changing my thermostat in my firebird. I didn't realize I purchased a new thermostat that opens at 195F. The old one opened at 170F (as inscribed on the bottom of the old thermostat). What is optimal running temp for this car....350 HO. Should I go back to the cooler opening thermostat? My car now runs 195F to 200F.

The reason I replaced the old thermostat is due to malfunction/sticking. Thanks.

I like the 180F thermostats.

I run a 180 as well. In fact we were driving on Daytona Beach today and it was 98* and at one point we sat for almost 20 mins just idling. Wife was driving and I kept asking, whats the temp, whats the temp. LOL She just kept saying it's between the first and second mark (stock rally gauge/temp gauge). The ole girl NEVER hit the half mark on the guage. In the old days, she would have hit the 3rd mark within in the first 5 mins of idling and would have been pegged and over heating after 10.

I still get excited over my flex fan as well. The temp gauge holding the same temp is a beautiful thing.

I'm pretty sure our cars originally came with 195* thermostats

The '68 service manual and the '68 diagnostic manual both show the "standard" thermostat was 190 F.

So, in reference to temp....as a general rule is cooler better? Haha..it made me feel better when my temp gauge said 170 to 180 vs 200.

I run a 160 degree thermostat with a 4 core radiator. I'm happy with it running at or below 180. By the way, there is no sludge buildup inside my engine. That's a myth.

I have a 350 with 69cc big valve heads and a cam similar to yours. I run a TH350 and 3.23:1 gears.

FWIW, my car's best runs(ET/MPH) are at 190*

I have a 180 and a four core, it holds right within a few degrees of 180 during any weather or runs, checked with one of those handy infrared thermometer things. I have coordinated that with the guage and noted the position (a needle width below half on mine)

I agree I usually run 180 Deg thermostat, but a word of caution about new thermostats, I no longer buy cheap autoparts store thermostats. The new "quality" of the ones from China leave alot to be desired, I have changed 6 in the last 2 years, and 2 of those 6 failed to open until 240 degs or more!!!!b Those were brand new!!!!
I now recomend only high quality Robert Shaw high flow thermostates or something equivolent.