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Thermostat info inside

Discussion in '308/328' started by AZDoug, Apr 13, 2021.

  1. AZDoug

    AZDoug Formula 3

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    This regards my '79 car, but....

    I found GT car parts has Behr Thermot-Tronic 56MM OD 165* (74C) T-stats in stock. Bleed hole drilled and everything.

    I typical would say 165* is bit on the cold side, but with carbed car,and low boiling point gas these days, it should help with heat soak/carb perc flooding after shut off..


    BTW, order the grooved sealing ring also for an extra dollar.

    I probably wouldn't use a 165* 'stat if I lived in Canada or Michigan, but in AZ, they don't seem to be a problem on other cars I have. But, i also drive far enough for the cars to completely warm up.

    Doug
     
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  3. mike996

    mike996 F1 Veteran

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    That's mighty low! I would go with whatever temp rating Ferrari specified. :cool:
     
  4. AZDoug

    AZDoug Formula 3

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    The problem with that is, the spec was done when gasoline wasn't ethanol added and had higher boiling points.

    Not sure how familiar you are with carbs cars back in the 1960s/1970s, early 1980s, but when you shut them off, Ford, Chev, my Ferrari (in the early 1980s), the carbs didn't boil over and flood the manifold/cylinders. They instantly started after sitting 10/20/60 minutes, or even next day because the float bowls were still full..

    Those same Fords, Chevs, etc, now carb perc and you have a massively flooded car, nothing changed except the fuel. Air gap manifolds help, but don't eliminate the problem. Only running engine temps lower (or running AV gas), stops the carb perc.

    Today, that 1960s/1970s car with a carb, even with a 180-190* T-stat, boils over and floods the car after shut off, resulting in extended cranking and a bunch of black smoke as the flooded car clears itself. And the following day, the float bowls are empty because of boil off and the fuel pump has to run for while to refill the carbs.

    The factory 195* Tstat, just lets this problem become a problem, washed down cylinder walls, dilutes oil, etc., because 195* lets the carbs boil after shut off

    You don't notice it with FI, because the problem cannot exist. I have four carbs cars, two i ahve had since the 1970s, (and the fcar, since 1984) and the problem didn't exist back then, but it does now.

    Doug
     
  5. mike996

    mike996 F1 Veteran

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    I guess if there is no other solution, putting in the lower temp T-stat is helpful but, of course, it adversely affects engine efficiency since the engine will never get up to its optimum operating temp. Oh well...life is full of trade-offs! ;)
     
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  6. AZDoug

    AZDoug Formula 3

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    Yes it is.

    FWIW, NASCAR motors run about 280-290*F as that gives better thermal efficiency(power), but it isn't ideal for everyday driver cars.

    Doug
     
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  8. mike996

    mike996 F1 Veteran

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    #6 mike996, Apr 14, 2021
    Last edited: Apr 14, 2021
    I had no idea NASCAR ran engine temps that high - what do they use for coolant? Or do they just run very high system pressure with water? At those temps, I would think anything but water would have insufficient heat transfer to deal with it.
     
  9. AZDoug

    AZDoug Formula 3

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    "About" 100% water with high pressure systems. The reason i say about, is I am sure they add a little bit of pixie dust to the water for this or that.

    Doug
     
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  10. mike996

    mike996 F1 Veteran

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    I know it can't be antifreeze since that's usually not allowed on race tracks and it would compromise the cooling capability anyway. So I suspect you are right - pixie dust! :)
     
  11. ragtop1

    ragtop1 F1 Rookie
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    hmm... Is that why I hear occasionally hear a little "puff" sound from one of the carbs when I turn off the engine?
     
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  13. Saabguy

    Saabguy Formula 3
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    Ya know I hadn't thought about that, makes sense. Granted I have installed electric fuel pumps on almost everything so all that i notice is a longer prime up time.

    Lester

     
  14. johnk...

    johnk... F1 Veteran
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    If the carbs were so hot that the gas in the bowls boils over dumping liquid fuel into the manifold, wouldn't the manifolds be even hotter and any raw fuel spilled into them boil off as well? The only thing heating the carbs would be heath transferred through their contact with the manifolds. No?
     
  15. Lawrence Coppari

    Lawrence Coppari Formula 3

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    I had my '87 328 serviced only once by professional mechanics that serviced Ferrari vehicles in the early 90's. They installed a 160 F thermostat. I have left it in because if it is not broken, I do not fix it. In very cold weather I have to put something in the oil cooler duct to get oil temperatures up to the 180 F mark.
     
  16. mike996

    mike996 F1 Veteran

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    328's have cooling systems that can keep engine temps in the optimum range under any conditions. I can't imagine why a mechanic would decide it needs a 160F Tstat...

    Sounds a lot like the old "remove the thermostat" thing that people did on Muscle cars...until they learned that the reduced temps just fouled plugs/reduced power.
     
  17. Lawrence Coppari

    Lawrence Coppari Formula 3

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    Prior to getting the Porsche I used to track the car at Ferrari Club events. The fellows who ran the shop were always at the events and were FCA well known members. Rockingham track in NC was miserably hot and humid during summer months. I suspect that is why it was done.
     
  18. johnk...

    johnk... F1 Veteran
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    Doesn't make sense. A 160 stat will just open sooner. If the temp still gets to 180 it makes no difference if the stat is 160 or 180 as it both will be wide open. And it it doesn't get to 180 it's running too cold.
     
  19. mike996

    mike996 F1 Veteran

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    I won't disagree re the Tstat for racing on the track. But what works best for track use and what works best for "normal" use of a car can be very different in many ways.

    Many (most?) things - from brakes, to tires, to suspension, to engine mods to fluids, etc - that are optimum for the track are not on the street.
     
  20. Lawrence Coppari

    Lawrence Coppari Formula 3

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    The temperature in hot weather never gets to the 180 mark unless the vehicle is not moving. But I have not tracked the vehicle since 1996 so I cannot say if it would get there now under track conditions. Cooling system works well. During sustained idle in hot weather the fans come on at 195 implying the temperature gauge reads accurately enough. I don't know why the thermostat was changed unless it was part of the major service and that is all that was on hand. I never asked them about it and soon switched to the Porsche for tracking.
     
  21. Lawrence Coppari

    Lawrence Coppari Formula 3

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    I agree.
     
  22. AZDoug

    AZDoug Formula 3

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    It is all evaporates in a few hours. Until then, thats why you have to crank your carb'd car over a long time until it cleans out the raw fuel.
    This is not something I just dreamed up, it has been a problem on carb'd cars for over 25 years (I do a lot of car related stuff with a lot of people with older vehicles, it isn't just 'my" problem), once fuel was switched over to lower boiling point fuel for fuel injection use. Low BP fuels burn better and help reduce emissions, unless you put it in a carb'd car, then you just get lots of unburned hydrocarbons released into the air.
    Doug
     
  23. AZDoug

    AZDoug Formula 3

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    You have fuel injection, you don't "have" a perc problem.
    Didn't you say you had a '60s Hemi Plymouth back when? Did it flood every time you turned it off back when? No?

    Well, they all do now.

    Doug
     
  24. AZDoug

    AZDoug Formula 3

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    That isn't how it works.

    A T-stat regulates the engine temp to about the t-stat rated temp plus maybe 10 degrees. If your radiator is operating properly. If the water comes back from the rad too cool, the T-stat just closes down some, if it comes back too hot, it opens more. if it comes back hotter than the radiator can cool it, the T-stat is fully open and it stabilizes at some temp where everything is in balance heat exchange wise.

    If you have a cooling issue, putting lower rated T-sats in will just open sooner, but the car will stabilize at whatever temp the heat exchange capability of the car radiator is, anywhere from above T-stat rating to so hot it hurts the engine.

    Carbed cars in general, like 180-185*F. The 195* stuff was for cat converter cars to up the operating temps, the reason they didn't go to 205, which is even better from a cat point of view, was even old fuel would perc at around 210-220F.

    Doug
     
  25. mike996

    mike996 F1 Veteran

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    "Didn't you say you had a '60s Hemi Plymouth back when?"

    Yes, I did, as well as several other (Mopar) muscle cars. I also professionally worked on/built/modified engines for for street, hi-performance and track use.

    "Did it flood every time you turned it off back when? No?"

    I never saw the flooding problem you are describing. If you are saying they all do it now I guess it must be the fuel issue you mentioned. Though I have to admit I can't see how fuel boiling off from the carb could eventually end up as raw fuel in a cylinder. But if it does, it does! ;)
     
  26. johnk...

    johnk... F1 Veteran
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    Not saying it doesn't happen, I've just never experienced it. My point was that if the gas in the bowl is getting hot enough to boil then it's at or the bulk is near atemperature where the vapor pressure is greater than atmospheric. (Boiling point is defined as the temperature where the vapor pressure exceed atmospheric pressure.) It follows logically that the manifold and other engine parts would be hotter, since that is where the heat comes from, and with the overflowing fuel already near the boiling point I would have though it would vaporize upon contact with the manifold. Maybe has to do also with local formations as well?
     
  27. AZDoug

    AZDoug Formula 3

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    That why they call it "perc" as in percolation, like the old fashioned coffee pots. Remember the Folgers coffee percolator commercials?

    The fuel spot boils in the carb bowls and pushes the fuel through the venturi siphon tubes into the throttle bores,and then it runs down under the throttle plates into the manifold/cylinders. This can happen during running conditions, esp at idle, also.

    https://www.jstage.jst.go.jp/article/jpi1959/9/0/9_0_58/_pdf

    Doug
     
  28. johnk...

    johnk... F1 Veteran
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    #25 johnk..., Apr 15, 2021
    Last edited: Apr 15, 2021
    Yes, I know it opens various amounts over a 10 degree range. My point, though poorly stated, was regarding that he said the car never gets to 180. Thus the 160 T Stat is causing the car to run too cold. Or that's how I interpreted the comments.

    I have a replacement T stat for my 85 QV that is 176*.
     

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