revisiting the thermostat issue

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Hi all. I re-read through the list of posts available on the subject of correct T/stat for the Cleveland. I have also checked various suppliers for dimensional info. All seem to list the depth from the flange underside to the bottom of the 'hat' at .820". This is where I'm getting confused. I thought the 'hat' was supposed to seal against the brass restrictor plate. If that is true, why does mine measure 1.020" from the flange seat (casting) to the restrictor plate. That's a .200" gap!! Yes, it is the original one.

Does that sound correct? If someone knows for sure, please reply ASAP. And no, I am not inclined to spend 60 bucks on fancy T/stat.

Thanks in advance,

Geoff.

 
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Thanks Qcode. Not the brightest bunny in the bunch am I!! I just took a so called 351C T/stat and dunked it in hot water. The hat does extend downward to reach the 1.02" dimension. However, now it's the diameter of the 'hat' that I am concerned about. The one I have is only .625 Diam. The Stant list the by-pass flange diameter as .66". The hole in the restrictor plate is about .75" as best as I can tell, so still no seal. I will look into your suggestion for the FlowKooler if it's available. I just spent 2 grand on new parts to hopefully fix my engine wows, what's another few bucks to do it right.

Thanks again,

Geoff

 
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Hi all. I re-read through the list of posts available on the subject of correct T/stat for the Cleveland. I have also checked various suppliers for dimensional info. All seem to list the depth from the flange underside to the bottom of the 'hat' at .820". This is where I'm getting confused. I thought the 'hat' was supposed to seal against the brass restrictor plate. If that is true, why does mine measure 1.020" from the flange seat (casting) to the restrictor plate. That's a .200" gap!! Yes, it is the original one.

Does that sound correct? If someone knows for sure, please reply ASAP. And no, I am not inclined to spend 60 bucks on fancy T/stat.

Thanks in advance,

Geoff.
You have an original thermostat? That would be very interesting to see and get measurements from.

 

Qcode351mach

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Thanks Qcode. Not the brightest bunny in the bunch am I!! I just took a so called 351C T/stat and dunked it in hot water. The hat does extend downward to reach the 1.02" dimension. However, now it's the diameter of the 'hat' that I am concerned about. The one I have is only .625 Diam. The Stant list the by-pass flange diameter as .66". The hole in the restrictor plate is about .75" as best as I can tell, so still no seal. I will look into your suggestion for the FlowKooler if it's available. I just spent 2 grand on new parts to hopefully fix my engine wows, what's another few bucks to do it right.

Thanks again,

Geoff
Flow kooler /Robert shaw 333-180

This is the correct one, same as I have installed in my car You have to call flow kooler http://www.flowkoolerwaterpumps.com/contact.html they dont show on the site the stamping is ct2101700s0003

I happened to have my car in heavy stop and go traffic this weekend for over 30 minutes, Was the first time I've had the car in traffic like this. locked in at 180 the whole time never budged :wrench: (non stock water temp gauge)

 
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Hi all. I re-read through the list of posts available on the subject of correct T/stat for the Cleveland. I have also checked various suppliers for dimensional info. All seem to list the depth from the flange underside to the bottom of the 'hat' at .820". This is where I'm getting confused. I thought the 'hat' was supposed to seal against the brass restrictor plate. If that is true, why does mine measure 1.020" from the flange seat (casting) to the restrictor plate. That's a .200" gap!! Yes, it is the original one.

Does that sound correct? If someone knows for sure, please reply ASAP. And no, I am not inclined to spend 60 bucks on fancy T/stat.

Thanks in advance,

Geoff.
You have an original thermostat? That would be very interesting to see and get measurements from.
Mike, Sorry. Now I'm getting others confused! Re-reading my post, I see where you could think I have an original t/stat. I was referring to the depth of the brass plate from the block casting seat (where the underside of the stat locates). I know my engine block is unchanged from factory. Sorry for the confusion, but yes, it would be nice to get those measurements if someone does have an original stat.

Geoff.

 
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Thanks Qcode. Not the brightest bunny in the bunch am I!! I just took a so called 351C T/stat and dunked it in hot water. The hat does extend downward to reach the 1.02" dimension. However, now it's the diameter of the 'hat' that I am concerned about. The one I have is only .625 Diam. The Stant list the by-pass flange diameter as .66". The hole in the restrictor plate is about .75" as best as I can tell, so still no seal. I will look into your suggestion for the FlowKooler if it's available. I just spent 2 grand on new parts to hopefully fix my engine wows, what's another few bucks to do it right.

Thanks again,

Geoff
Flow kooler /Robert shaw 333-180

This is the correct one, same as I have installed in my car You have to call flow kooler http://www.flowkoolerwaterpumps.com/contact.html they dont show on the site the stamping is ct2101700s0003

I happened to have my car in heavy stop and go traffic this weekend for over 30 minutes, Was the first time I've had the car in traffic like this. locked in at 180 the whole time never budged :wrench: (non stock water temp gauge)
Thanks Qcode, I'll look into that. Maybe I can get lucky for once.

Still, no-one has told me if the bottom of the 'hat' is supposed to completely close off the hole in the restrictor plate, or whether there is supposed to be some water flow past it. I'm definitely getting a better handle on this, but still have questions. I have not yet taken a bore gauge to measure the exact diameter of the plate hole to compare with the diam of the 'hat'. I'll do that today and post later.

OK, I measured the inside diameter of the restrictor hole and it is 3/4" or .750" That would mean a gap of .045 - .050" all around using the Stant description of .660" diam. for the by-pass flange. Hmmm!

 
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Don C

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The original design did not close off the hole, and is one of the reasons that (mostly) Pantera owners object to them. Due to manufacturing tolerances (especially aftermarket thermostats) and the way the thermostat fits in the groove in the block it's probably not possible to completely close the hole with that style of hat.

This same type of bypass is used on Ford's modular engines. However, it uses a different style of "hat". Did you see my article at:

http://www.7173mustangs.com/thread-351c-cooling-system

 
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The original design did not close off the hole, and is one of the reasons that (mostly) Pantera owners object to them. Due to manufacturing tolerances (especially aftermarket thermostats) and the way the thermostat fits in the groove in the block it's probably not possible to completely close the hole with that style of hat.

This same type of bypass is used on Ford's modular engines. However, it uses a different style of "hat". Did you see my article at:

http://www.7173mustangs.com/thread-351c-cooling-system
Thank you Don. Now I do have a better idea of how it is supposed to work. I printed off your article and I notice that the diameter of the 'hat' is .66" (as is Stant's), so obviously it will never completely seal, just restrict the flow. Water will always take the easiest rout.

I feel more confident using the t/stat I have now I know what's what.

Awesome help from all, which in turn will help others I'm sure.

Geoff.

 

barnett468

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Here's one of the problems with the parts they sell . These are both aftermarket t stats . The hat on the one on the right is installed deeper than the one on the left plus it is crooked . Poor fitting and/or poor operating factory parts is also what occasionally plagued this system when the cars were brand new.

I just get rid of the stock system and use a bypass plate or plug the factory bypass plate with a freeze plug with a 1/8" hole in it then use a Windsor high flow t stat and drill 4 small holes around the perimeter of the t stat . If you have an unmodified Weiand pump you have to do another mod.

robertshaw_333_192_4.jpg


You can buy a t stat like this . This guy makes a new hat and insert from solid brass so it works properly . It also looks slightly larger and taller to insure a good seal.

http://www.ebay.com/itm/182107945649

s-l400.jpg


http://www.ebay.com/itm/171476456933

s-l400.jpg


 
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Here's one of the problems with the parts they sell . These are both aftermarket t stats . The hat on the one on the right is installed deeper than the one on the left plus it is crooked . Poor fitting and/or poor operating factory parts is also what occasionally plagued this system when the cars were brand new.

I just get rid of the stock system and use a bypass plate or plug the factory bypass plate with a freeze plug with a 1/8" hole in it then use a Windsor high flow t stat and drill 4 small holes around the perimeter of the t stat . If you have an unmodified Weiand pump you have to do another mod.

robertshaw_333_192_4.jpg


You can buy a t stat like this . This guy makes a new hat and insert from solid brass so it works properly . It also looks slightly larger and taller to insure a good seal.

http://www.ebay.com/itm/182107945649

s-l400.jpg


http://www.ebay.com/itm/171476456933

s-l400.jpg
Thanks Barnett. As I said before, my decision is based on cost because of shipping and apparently import duty and the 30%+ exchange on the dollar. Next time I'm in the States for an extended time, I may order one and bring it back with me. I have my immediate question answered, not perfect, but I have had no problem with an even worse fitting stat. I don't anticipate any problems going with a Stant.

Geoff.

 

Don C

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Water will always take the easiest rout.

Geoff.
Yes, water will generally take the easiest route. However, many factors influence the actual flow rate or quantity flowing. These factors are usually expressed as "friction". The roughness of the wall of the object the water flows through, elbows or bends, and protrusions all produce frictions to the flow, reducing actual flow rate/quantity. In the case of a protrusion, not only does the protrusion reduce the flow, the downstream eddies add additional friction to against the flow.

In the case of the thermostat and hat, mathematics tells us that about 20% of the opening remains after the hat closes off the opening. However, due to the size and shape of the remaining opening the actual flow will be considerably less than the 20%. How much will depend on what the frictions are downstream of the flow through the block and heads for the non-bypassed coolant, as well as the flow through the bypass.

Were you able to get the accurate dimension of the opening in the restrictor plate? I haven't been able to get that from anyplace, and haven't wanted to pull my thermostat housing bad enough to get it.

Thanks, Don

 
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EBSTANG

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Water will always take the easiest rout.

Geoff.
Yes, water will generally take the easiest route. However, many factors influence the actual flow rate or quantity flowing. These factors are usually expressed as "friction". The roughness of the wall of the object the water flows through, elbows or bends, and protrusions all produce frictions to the flow, reducing actual flow rate/quantity. In the case of a protrusion, not only does the protrusion reduce the flow, the downstream eddies add additional friction to against the flow.

In the case of the thermostat and hat, mathematics tells us that about 20% of the opening remains after the hat closes off the opening. However, due to the size and shaped of the remaining opening the actual flow will be considerably less than the 20%. How much will depend on what the frictions are downstream of the flow through the block and heads for the non-bypassed coolant, as well as the flow through the bypass.

Were you able to get the accurate dimension of the opening in the restrictor plate? I haven't been able to get that from anyplace, and haven't wanted to pull my thermostat housing bad enough to get it.

Thanks, Don
...3/4", his post, yesterday 8:52 am

 
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Thanks, I missed that. 0.75 is what I used.
Thanks Don and everyone else. It has been an interesting re-read on this subject. No doubt it will help many others (who we never here from) decide what is the best solution for their 351C's. I do appreciate all the responses which have cleared up my questions.

One thing I learned is that 351C are NOT the same as 351M or 400's. M's and 400's have cast in restrictors not brass and I'm thinking that the ID is a bit smaller as (and not to knock NPD) but the ones they sell listed for the 351C in the catalog are only .625" diam. 'hat' whereas Stant is .66" diam. What else I noticed was that they are marketed as Parts Master brand. The 180 deg. has a label listed for a 79 Bronco 351M /400, while the 192 is labeled for the 351C. Other than that, they are identical. Hmmm! ( I'll be taking them back)

Buyer beware I guess. Go with proven brands for Cleveland's or spend the big bucks and get the custom made ones.

I think we have covered all scenario's for now.

Geoff.

 
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