Shewman's High Flow Thermostats

[Old Henry]

If you look at the picture of the thermostat currently being sold for the 59A engine (post # 33) you'll see what's called a "jiggle plug" that falls down to let the air through when filling the engine

then lifts up to block that little hole when the engine is running.

The Stant stat next to it, which is for a 1990 Subaru Justy among other modern cars, doesn't have that and would probably need a little hole to let the air through when filling. I believe that the holes drilled in these thermostats to increase flow are drilled all around that same surface that the jiggle plug is in. There is no where else to drill them. But, the mere fact that whoever designed and built this thermostat went to the effort to create a way to plug that one little hole when not needed for filling shows how important it is for the stat to close off entirely to work properly and how adding holes defeats the purpose of the thermostat.

G.M. and Bob Shewman swear that drilling a bunch of holes in thermostats lets more water through and makes them better for hot weather. That's probably true but it defeats the purpose of the thermostat in cold weather or a long descent from a high mountain in hot weather.

 

[flatjack9]

Keep up the quest Old Henry. I'm pulling for you. Drilling holes all around the thermostat to make it high flow is a joke.

 

[Old Henry]

Keep up the quest Old Henry. I'm pulling for you. Drilling holes all around the thermostat to make it high flow is a joke.

And that from a guy with a mechanical engineering degree that worked for 9 years designing and testing gasoline engines. Got to carry some weight.

Thanks.

 

[Old Henry]

Here's what all modern thermostats are competing against - Ford's original design.

These are NOS Ford stats for my 47 that a very kind barner has offered to sell to me. Just compare them with the modern stats and you'll see the real advantages of them. They have a butterfly valve that swivels clear out of the way of water flow. And, look at the size of that hole once it's opened up! Way bigger than any modern stats. And, the mechanism that opens it is small and much less intrusive into the water flow than modern stats. This is what I've been looking for and believe that, if they still work (I'll test before installing), they will work better than any modern substitutes for those reasons.

 

[VeryTangled]

Wow that is GOLD.

Having a good time following this thread and learning a lot.

Prof. Henry, is there any chance you can post more photos when you get them? I'd be especially interested in seeing one in the open position.

I'd also be interested in their opening temperature, and their closing temperature. It seems you will be interested in them closing correctly as the fluid cools on descent, preventing the temperature from dropping into an abnormally cool operating range, after being open during ascent. As I read it this is one of the areas you're looking for to get good performance.

-VT/JeffH

 

[Old Henry]

I will give a full report with pictures upon receipt of them.

 

[ken ct]

Hope they work.If they do you better put that Barner on your yearly Christmas List.He has some generosity in droves. Good luck. ken ct.

 

[Old Henry]

Bought the Stant stat today and heated it up with the current replacement and here's what I learned.

Looking up through open stats.

Looking down through open stats in the water.

Just the appearance should convince of the higher flow of the Stant stat. If not, here's the data: The diameter of the opening above the valve for the water to pass through (the sharp metal edge) is 25 mm for the brass and 28 mm for the Stant. That alone is a 25% increase in space for the water to go through. The diameter of the valve plates is 27.5 mm for the brass one and 29 mm for the Stant. But, once that valve is out of the way that difference doesn't matter so much. The difference that really matters in the 25% larger opening of the Stant stat. Then you have the issue of the space above the valve seats that the water must pass through. That's where the biggest difference is as you can see in the pictures. Just eyeballing it I don't think the total area of the openings above the valve seat on the brass one is even equal to the area of the valve seat. So, the real restriction in the brass one is those openings that are so small. Whereas, as can be seen in these and the previous photos, there really isn't any restriction above the valve seat in the Stant stat. Those openings are clearly bigger than the area of the valve seat.

So, my analysis suggests that the Stant stat has at least 25% higher flow than the standard brass ones now being sold for the 59A engines and likely even higher. To increase the volume of the brass stat to that of the Stant one you'd have to drill thirteen 1/8" holes in the space between the valve plate and the inside of the head neck, if you could fit them in there. But then, of course, you'd have a defective and pretty much worthless thermostat. And, the Stant stats are 30% cheaper than the brass ones - $7.00 from most suppliers compared to $10.00 for the brass one.

 

[51 MERC-CT]

The 12% sounds good but if you calculate the area of the openings you will find it to be more in the 25% range not counting the severe restriction on the brass one, then it looks more like 35-40% if not more.

 

[Old Henry]

The 12% sounds good but if you calculate the area of the openings you will find it to be more in the 25% range not counting the severe restriction on the brass one, then it looks more like 35-40% if not more.

You're correct. I fixed my error in my post.

Thanks

 

[Bluebell]

So having come this far, Just how much flow is required, and why do much bigger engines (of much higher hp output) function well with half as many thermostats? (I know about the ex. ports)
How many gallons per minute will flow through the standard stat, fully opened? and how many gallons per minute are required to meet the needs to sufficiently cooling the FHV8?

 

[Talkwrench]

Bluebell I was thinking the same thing...

 

[Old Henry]

So having come this far, Just how much flow is required, and why do much bigger engines (of much higher hp output) function well with half as many thermostats? (I know about the ex. ports)
How many gallons per minute will flow through the standard stat, fully opened? and how many gallons per minute are required to meet the needs to sufficiently cooling the FHV8?

I don't know all the answers but I'll take a stab at a couple.

The only reason the flathead has two stats is because it has two water outlets, one for each side of the engine. Modern engines of any size do not have two separate sides like the flathead as far as I know. I suppose if you connected the two water outlets together with a pipe that size and had an even bigger hose to the radiator you could get by with one stat going from the T into the single hose.

As far as actual flow needed to adequately cool a flathead, I wouldn't think there is one number. It depends on how hot the fire is in the engine. Very little flow is sufficient at slow speeds on even ground but a much larger higher flow is needed going at high speed up a hill. Anything less than ideal conditions of the engine block and/or radiator is going to require even more flow to make up.

My 2¢

 

[Bluebell]

As JWL elluded to previously. The stat effectively stops or limits the water flow through the radiator until the stat begins to open (say 180F) it is fully open at say(200F)
These stats shown so far are all wax type stats. The wax expands to open them and contracts to close them. This is an action governed by the laws of physics.
They are reliable. If your engine is fitted with them with no extra holes drilled in them, they will not begin to open until the water on the wax pellet side of the stat reaches the designed temp. Your engine CAN run colder under extreme external conditions, but for most of you in the lower states your minimum operating temp is governed by the opening temp of those stats. This is good.
At the other end of the spectrum, conditions COULD be such that there is not enough differential between ambient temp and boiling point. I don't know how close these two temps can be, but it's going to be pretty hot.
In these circumstances your stat is going to be wide open, and I doubt that flow though the stat is going to be the limiting factor.
The point really is that most (I said most) people will have other issues with there vehicles, be it a dirty cooling system, loose belts, timing, (who always has their engine perfectly timed?) brakes dragging, fuel mixture,under inflation(tyres) and possibly a whole bunch of other things including up specing.
All of these things have to be 100% right, before we blame the thermostats.

Is Bob S. a member and can he give us a run down on any research he might have done?
Does anyone have any flow specs?

 

[Old Henry]

Is Bob S. a member and can he give us a run down on any research he might have done?
Does anyone have any flow specs?

Bob Shewman is not a member as far as I know, at least I've never seen him ever comment on here about his stats, only G.M. He does have an email address: gadgiteer@aol.com and does answer his phone or return calls, at least he did mine and answered all of my questions. Apparently G.M. had something to do with development of Shewman's thermostats and may chime in here with any test results he did. Knowing now how Shewman's stats are made, the test I'd be interested in is how long it takes to get up to operating temperature with his stats at 0° and how low his stats let the engine temperature go on a long descent down a mountain. That's where I have my real doubts about them.

 

[Old Henry]

The point really is that most (I said most) people will have other issues with there vehicles, be it a dirty cooling system, loose belts, timing, (who always has their engine perfectly timed?) brakes dragging, fuel mixture,under inflation(tyres) and possibly a whole bunch of other things including up specing.
All of these things have to be 100% right, before we blame the thermostats.

I totally agree with you. Even taking out stats is not going to fix a serious problem somewhere else. But, a good high flow thermostat might make up for some other weaknesses in the system to a certain extent. That's the only reason I've spent so much effort studying them.

 

[Bluebell]

Henry, I wouldnt publish his number in this public place.

I agree with your line of thought. I have enjoyed your postings. the photos make a big difference.

 

[Old Henry]

Henry, I wouldnt publish his number in this public place.

Fine. I took it out.

 

[G.M.]

Bob Shewman is not a member as far as I know, at least I've never seen him ever comment on here about his stats, only G.M. He does have an email address: gadgiteer@aol.com and does answer his phone or return calls, at least he did mine and answered all of my questions. Apparently G.M. had something to do with development of Shewman's thermostats and may chime in here with any test results he did. Knowing now how Shewman's stats are made, the test I'd be interested in is how long it takes to get up to operating temperature with his stats at 0° and how low his stats let the engine temperature go on a long descent down a mountain. That's where I have my real doubts about them.

I did extensive testing on gadgiteers stats in 40 to 100 degree temperatures and have been using them over 2 years. I'm talking about every day for 3 or 4 months with the same 20 mile drive to lunch, engine sitting for 30 or 40 minutes take temp, starting and return back to the shop. I don't just drive around the block and start talking how great something works, I test it for months before I mention it. I have at times posted things I was testing with the new gas problems. I jump out every time as soon as I stop and take measurements on the heads at the water outlets 1/2" below the top hoses. This is the output of both sides of the engine which are separate cooling systems not connected in the engine. The water in the top radiator tank is a mixture of both sides of the engine this temperature is a mixture of both sides and will not tell you if one side of the engine gets hot. EVERY time I took temperatures both sides of the engine were within 2 degrees of each other on 3 different engines and I still check once in a while. One real benchmark in testing for cooling or heating in this case is my 39 P/U Mr Coool that has Skips pumps, anti freeze, Purple Ice, a 6 bladed industrial fan, 4 lb pressure cap, water filled up to the neck of the filler opening and a shroud. This engine sat at a fast idle in 100 degrees at a EFV8 national show for over 2 hours and never got to 180 and when raced slightly the temperature came down a few degrees. With Napa 111 stats and 8 holes in each flange on a 90 degree day this same truck ran at 195 driving due to a restriction of water flow from the restrictive openings in the 111 stats. These are the same stats that I ran across the other day that I offered to you which the offer is still open. I have a collection of old and new stats I purchased over the years trying to find stats that worked. My posts are based on actual tests and the results not on what I think should or will happen. I found out years ago these WAGS (wild *** guess's) on what I thought would work didn't always work. I made a lot of impellers for Skips pumps testing each on a water pump test machine and in 5 minutes find a weeks work was a waste of time. As soon as I put the turbine impeller on the machine in 5 minutes I saw it pumped almost double the water than any pump we ever tested. Even without two pumps to test on an engine I had patterns made and castings were ordered. Skip worked for me on my collection of old Fords for over 20 years and I gave him the coils, pumps and pressure valves as his own project I have no financial interest. The same with Bob Shewman he ran the machine shop in my manufacturing business until we both retired. I developed the flex hose, vented carb spacer and the thermostats for Bob and did all the testing and worked out production problems with him. I have no financial interest in Bob's business either. Both Bob and Skip are quality oriented and every part is tested before shipping. Skip tests every pump, coil and distributor and Bob hot water tests every thermostat to make sure they open in the proper range before shipping. Both stand behind their products and have repaired any problems no matter how long the part was in service at no charge. I do know in 40 to 50 degree weather the engines come up to 180 in 4 or 5 miles with no pre warm up. What they do at zero I don't know. Like I said before get a set of Bob's stats and if they don't work return them for a full refund. G.M.

 

[Old Henry]

I have enjoyed your postings. the photos make a big difference.

Pictures save a lot of words (such as in post # 59). It would be interesting to see such close-up detailed shots of Shewman's stats to see what they're really like. I can only imagine.