Reply to "Thermostat Source?"

The 333 series went back into production earlier this year and quickly sold out. I'd bet that some business specializing in the 351C bought a large quantity, like TMeyer or MME. I don't support either of those businesses, but if that's where you have to go to acquire a thermostat, so be it. I've been told one of the large Mustang parts businesses also hoarded a large quantity of the thermostats.

I've known a couple of people to have problems with the substitute thermostats. That's my only problem with them. They are not high flow thermostats like the original, and they have no positive stop (over-travel prevention) feature either. If the thermostat "over-travels" the brass orifice, the hole below the thermostat re-opens and allows coolant to recirc when the engine is operating at its hottest! A couple of people having overheating problems asked me for advice, I advised them to replace the substitute thermostat with a 333 series, and the overheating was resolved. So I developed a negative attitude about the substitute thermostats.

Way back when I first ventured onto the internet I waged a one-man campaign to raise awareness about the proper thermostat for the 351C. Its benefitted a lot of people. Robertshaw's decision to cease manufacturing the 333 series thermostat makes me sad, and it doesn't make sense, because the 333 series is very close to the 330 series, which is still in production.

If a person owns an older 333 series thermostat, the copper flange on the bottom can be carefully removed with a puller, and carefully pressed back onto the bottom of a new 330 series thermostat. The only difference between the two series is the copper flange. The 330 series is a rather universal thermostat that fits SBF, SBC and Mopar as well. It should be around for a long time.

In the mean time there are other options I shall pursue.