Shewman's High Flow Thermostats

[Old Henry]

I've still got a little heat problem and was considering installing Bob Shewman's "high flow" thermostats. He sent me some photos



but they really didn't show very well how they worked so I just called and talked to him about them so that I could understand what makes them higher flow than the standard stock syle thermostats now available for our flatheads. I thought maybe it had a butterfly valve that folded up and moved clear out of the path of the water to increase the flow or something else more "magical". What he told me was that he bought 400 military surplus 180° thermostats that work the same as the standard ones with a valve surface that opens and closes by a spring heating up and cooling the same as the others. He soldered a bushing around the tubular stat to make it fit tight in the flathead upper hose and drilled holes through the control valve to let more water through. That's it. So, it looks like to me that his "high flow" stats are nothing more than standard thermostats with a bunch of holes drilled through the control surface to increase the flow. Of course, that increases the flow both when the stat is open and when it is closed, which, in the winter may not let the engine warm up to temperature at all. All things considered, for $50.00 per pair, looks like I could drill holes in the stats I've already got and get the same benefit/detriment. Not condemning, just informing.

Note. This is for the 32-48 stats. The ones he sells for 49-53 are different. I did not discuss those with him.