Shewman's High Flow Thermostats

Old Henry

Old Henry

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

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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. :cool:

Note. This is for the 32-48 stats. The ones he sells for 49-53 are different. I did not discuss those with him.
 
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Henry, Why not leave out your thermostats altogether and use a radiator cover till the engine warms up in the morning?

Or... you could install a pair of big brass gate valves with shiny red handles! :D :D
 
ford38v8 said:
Henry, Why not leave out your thermostats altogether and use a radiator cover till the engine warms up in the morning?
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I've tried that. I'm not vigilant enough to watch the temperature gauge to know when to stop and take the cardboard out so I end up overheating in the winter. As I've said in response to this same suggestion before, the way I drive climbing up the steep side of a mountain and then down the other steep side, I'd have to be vigilamt enough to remember to stop and take the cardboard out at the bottom of the mountain and then stop again and put it back in at the top not to mention all of the shorter but still lengthy ups and downs on both sides. I don't like to see my temperature gauge go from 200 to 100 in a matter of minutes - can't be good for the engine I wouldn't think. So, I opted for Henry's idea - thermostats. Crazy idea I know but there you have it. :cool:

The manual valves would be even more work than the cardboard. :(
 
well you wont stop the temp going from 200 to 100 when you have been climbing working the engine then coming down the mountain the air will cool the radiator down you are fighting a losing battle against science
 
I actually tested it and that is not correct. The thermostat does, in fact, keep the engine from cooling down below the thermostat setting.
 
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Drilling relief holes in t-states is an old time solution that helps them open sooner, and at the same time flow more.
 
It may be possible to modify the later high flow thermostat to fit inside the 59AB hose.
 

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I was driving around today out side temp got up the 75 and the Ford temp was a little under 1/2 way. No problem over heating.
 
Many years ago I purchased some thermostats for the 48 back flathead engines that have a dial to set the opening temperature at 140 up to 190. With my '40 I set the dial on the thermostats at 140 year around. In KY my car runs 160 in the winter time and 160 to 180 in the summer. No holes drilled or changes to the original design. They fit in the heads and I think the brand name is Doyle. Maybe wrong about the name since I put them in about 2 years ago. The 140 gives a very good range and will not let the engine drop below 140 at any time after the engine warms up above the 140 mark. I have Carpenter new design water pumps on this particular '40 I'm referring to.
 
ford38v8 said:
Henry, Why not leave out your thermostats altogether and use a radiator cover till the engine warms up in the morning?

Or... you could install a pair of big brass gate valves with shiny red handles! :D :D
Click to expand...

Old Henry said:
I've tried that. I'm not vigilant enough to watch the temperature gauge to know when to stop and take the cardboard out so I end up overheating in the winter. As I've said in response to this same suggestion before, the way I drive climbing up the steep side of a mountain and then down the other steep side, I'd have to be vigilamt enough to remember to stop and take the cardboard out at the bottom of the mountain and then stop again and put it back in at the top not to mention all of the shorter but still lengthy ups and downs on both sides. I don't like to see my temperature gauge go from 200 to 100 in a matter of minutes - can't be good for the engine I wouldn't think. So, I opted for Henry's idea - thermostats. Crazy idea I know but there you have it. :cool:

The manual valves would be even more work than the cardboard. :(
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Back about 1960 a neighbor had a '57 brand X that he brought down from Canada. A heavy material roller shade was fitted to the front of the radiator. A system of pulleys allowed the pull cord to be run in to the passenger compartment. This arrangement allowed full control of the air flow through the radiator by the driver. Sort of like a manual version of the radiator dampers on diesels.
 
L78CHEVELLE said:
Many years ago I purchased some thermostats for the 48 back flathead engines that have a dial to set the opening temperature at 140 up to 190. With my '40 I set the dial on the thermostats at 140 year around. In KY my car runs 160 in the winter time and 160 to 180 in the summer. No holes drilled or changes to the original design. They fit in the heads and I think the brand name is Doyle. Maybe wrong about the name since I put them in about 2 years ago. The 140 gives a very good range and will not let the engine drop below 140 at any time after the engine warms up above the 140 mark. I have Carpenter new design water pumps on this particular '40 I'm referring to.
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L78,the brand you are thinking of is "DOLE" / they made many Therm back in the day. ken ct.
 
I have a pair of mr gasket thermostats that fit in 49-53 housings,they are made for racing ,160 or 180 looks like bobs to me
 

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I could not get my 35 engine over 140 without stats, I now have Roberts and run 180-190 driving very hot days. The only problem I encountered was a small bit of overflow when the stats opened due to surge of coolant to the tank. Took coolant level down a bit and no more overflow. I do not run a pressure cap and the overflow tube is not blocked. I'm happy.
 
Terry you need Skips 3 lb pressure valve on the bottom of the over flow tube. Running with a low water levels decreases the amount of coolant in the system causing higher operating temperature. It is a 22 quart system not 17. G.M.
 
on my 59 motor in my 41 PU, i took prestone 180 degree super stats, ground the outside down a litttle so they were slightly larger than the outlet of the head and so when i pushed the hose down over the stat and outlet neck on the head and clamped the hose, the stat never moved and i was able to use modern stats. they had enough flow that i only had it heat up at idle with low airflow through the radiator..... don
 
Thermostats for model A's are made with modern thermostats ground down as pictured above. They have an 1 3/4 " thin tube tig welded to the rim to stabilize the unit in the hose. Don't know if this would flow enough for a V8.

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John
 
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