Thermostat--Yes or NO

Kurt, that is truly amazing. I assume you are right on the cyl walls and not on the diff. sections of the head; since the head runs a fairly consistent temp.
If I had your results, I would not hesitate to run a stat.

i have worked on many many Model A motors in this shop and every single one has the same results I posted above.
My assumption is that the water pump sucks the cooled water from the inlet immediately forward; allowing very little to disperse rearward. I find this to be true even tho the blocks were modified at some point with a diverting baffle at the inlet....it just isn't enough
 
I ran with a 160 degree thermostat for several years but stopped upon reading about the lack of a backup flow system in the Model A Ford. In the Model A, when the thermostat is closed effective water circulation all but ceases in the engine.

You can correct this by making your own bypass system --- a hose connection between the water pump and thermostat directed to the lower hose; however, it would be easier to just block off some air flow to the radiator via cardboard as previously suggested. It's my impression that most cooling systems allow some water circulation in the engine when the thermostat is closed.

It seems that cardboard is one way to go but since you use the car daily this might not be the answer. A thermostat will certainly aid in getting the engine up to optimum heat quickly but I would devise a back up water circulation system with its use.
 
Peyton said:
I ran with a 160 degree thermostat for several years but stopped upon reading about the lack of a backup flow system in the Model A Ford. In the Model A, when the thermostat is closed effective water circulation all but ceases in the engine.
Click to expand...

That is why two additional 1/8" holes (for a total of 3) are drilled in the thermostat.

Peyton said:
You can correct this by making your own bypass system --- a hose connection between the water pump and thermostat directed to the lower hose;
Click to expand...

What your suggesting here is to bypass the radiator. Not really a good idea. You will be re-circulating HOT water. You would be surprised how much water flows thru a 3/8" hose.

On Y-Blocks (Y-8's) we actually restrict the thermostat bypass by inserting a plug with a 1/8" orifice. So 3 1/8" holes should be plenty for a Model A.
 
Last edited:
I agree with the two holes in the thermostat to let some water get thru but wouldn't the thermostat begin to open up and let water pass at the desired temp even with the bypass. Then it would pass thru the radiator.
 
W/O any bleed holes or bypass loop through a heater, until the thermostat opens, no water circulates, and you can actually have hot-spots in the block to the point of boiling, until the water near the stat gets hot enough to expand the capsule / bellows.

The bleed holes allow a tiny bit of circulation, not enough to defeat the purpose of the thermostat, but to allow enough coolant to pass through the stat to allow it to heat-up quicker.

Another option would be to get tappings in the outlet and inlet necks, and run a bypass tube between.

I find that a couple of 1/8" holes drilled in the thermostat plate do just fine.

Frank
 
Just poke a 160 thermostat in the upper or lower end of the UPPER hose & FORGET it!
This subject has been TOTALLY OVER-THOUGHT!
If you DON'T need a thermostat in FLORIDA, how come ALL MODERN cars have them?
I gotta' go EAT.
Bill Cool Fool
 
tbirdtbird said:
Bill, no comparison.
Moderns need to run at 210° in order to get the emissions controls where the feds want them. And moderns are pressure systems. Just try to run a non-pressurized A at 210° and see how well that goes
Click to expand...
POINT TAKEN, T-Bird,
But we're just talking about a 160 thermostat in a Model A, to warm up faster, control & coordinate the flow from the engine to the radiator. The engine is a water HEATER & the radiator is a water COOLER & a thermostat to monitor and control the flow is a MUST.
Modern thermostats RARELY fail. The control cartridge is filled with WAX, that expands with heat & pushes the valve open. If one of the side straps breaks it ***** the valve open & SUDDENLY the temp drops. If the other side strap breaks, the valve sticks CLOSED & then it REALLY gets HOT!
Putting a thermostat in a Model A is no different than the first thermostats in Fords' Flathead V-8, just pop off the upper hose, plop in a thermostat & put the hose back on, EASY!:D
I put 400 to 500 miles a month on Minerva, with a 160 thermostat in the UPPER end of the UPPER hose & a roofing nail in the overflow & it worked PERFECT! EVEN in 112 Degree weather! She had a Walker 10 fin per inch radiator & I backflushed it once a year.
Bill W. (The Dog:cool: agrees!)
 
Last edited:
The thermostats that I've seen offered for Model A Ford are rated at 160 degrees.

It was explained that due to the politically correct corn syrup laced gasoline that we are forced to buy and use in the good old U S or A, that the ancient four-banger Fords operate better when hotter.

So they say . . .
 
Capt Quahog said:
The thermostats that I've seen offered for Model A Ford are rated at 160 degrees.

It was explained that due to the politically correct corn syrup laced gasoline that we are forced to buy and use in the good old U S or A, that the ancient four-banger Fords operate better when hotter.

So they say . . .
Click to expand...

"THEY" say a lot of things.
 
Seems I did the right thing in starting this thread, as I now have more knowledge than I started with. But it does show there is quite a bit of difference in the way everyone views the use of thermostats in Model As. I was always under the impression that cool engines performed better, the old hot rod guy in me, and since fuel mileage has never been an issue with me, as well as ethanol since I use Sunoco Rec 90 ethanol free, it looks like I still have a lot to consider. I will continue to read every ones input and try to draw on there experience.
 
a cold engine does not perform as well as it could, and combustion will not be as complete. Ideally I would like to run my A at 180, but as I mentioned above, the poor cooling of cyl 4 stops me from doing that, at least on all the cars I have worked on
 
A warmer running engine also vaporizes water and other BAD things made in the combustion process along with any unburned hydrocarbons that slipped past the rings and into the crankcase prolonging the life of your engine. :p:p
 
Last edited:
My engine builder insists on a 180° thermostat. So much so that he even furnihsed the stat.
 
I tried both ways as I thought I was overheating as a result of the stats. Turned out Fan was to small. I was using a 4 blade 12 inch dia. I got somewhere as I had some clearance issues using a fan rigged pulley on the alternator. Went to an auxiliary electric fan on front between radiator & grill with a 180 electro-stat and heating probs went away. After that engine wouldn't get to temp so I put the 180 stats back in and it runs between 180 and 190 now. Many say you need the stats to slow the water down so it can absorb more heat from the engine.
 
Question? If stats are not necessary, why do all manufactures put them in all the new cars? There are advantages for the engine to operate at constant temperature, regardless of the out side temperature.

JB
 
No need for one where you live.
Failure mode of a stat is over heating.
KISS. Keep It Simple Stu...well. you know.:D
 
Jerry in Shasta said:
Question? If stats are not necessary, why do all manufactures put them in all the new cars? There are advantages for the engine to operate at constant temperature, regardless of the out side temperature.

JB
Click to expand...

Modern engines will operate at peak power and burn off moisture thereby reducing oil oxidation and sludge formation.

You wont realize those advantages with an A engine because they don't make much power to begin with, and we change the oil often anyway.
 
I have a modern motor with insert bearings and large valves and a new style radiator. I have a mechanical thermostat in the water neck. It gives very accurate readings of the water temperature in the neck which is right below 160 degree thermostat. The car was set up this way when I purchased it. I put about 2,000 miles on the car with no problems. But I like to Tinker so when I was changing out my antifreeze for the season I decided try and run the car without a thermostat. The car took a very long time to warm up and ran very poorly until it came up to heat. I reinstalled a new thermostat and it has been running great at a very constant temperature in all seasons. This may not work for everyone but it works very well for my car.
 
Have a friend with a '29 roadster PU that I helped a few weeks ago. Kept overheating. Yeah, you guessed it. His T-stat was about 5 years old.
 
You must log in or register to reply here.
Back
Top