RE: Cooling system mods

[Robert Ducker <bducker@domain.elided>]

Greetings Brian...

I think you're probably right about the OZ leaded vs unleaded, although
here in Texas we have 92 octane (R+M/2) unleaded available from most
stations. But, it seemed to take about 10-12 years after our unleaded law
went in before decent high octane unleaded became very widely available
(hopefully quicker in your case).
The thermostat I'm talking about is used on my '73 Stag and is different
from the earlier models by having a spring loaded disk on a shaft that
extends an inch or so back into the housing when installed. There is a
passage opening right behind the disk that seems to be for warmup bypass,
and would probably cause overheating if the disk does not fit tightly over
it after warmup. My concern was about how close it should be when
installed. It should probably not be under spring pressure as I mentioned
before; a number of cars use a spring loaded valve for this purpose, but
the Stag's water flow seems to be in the other direction! But I still think
that it needs to be less than about 1/8 inch.
Concerning thermostats, an old hotroders trick around here is to drill
holes around the circumference of the thermostat to increase coolant flow.
Temperature regulation will still take place as long as it doesn't get too
cold outside. Five 1/4 inch holes will add about 25% to the maximum opening
of a stock thermostat. This works very well in Fords and Chevys, but I
haven't tried it yet in the Stag.

Robert Ducker

At 09:51 AM 11/5/97 +1100, you wrote:
>Robert
>
>greetings from OZ.     I have been watching the discussion on thermostats for
>a while with interest.  I am intriqued with the comments referring to the
>thermostat with a disc .
>
>Frankly, I have never heard of this before, I replaced mine back in about 89
>and just rocked down to the local auto parts shop and bought a common old
>garden variety thermostat, same as I would put in my 2500 sedan or any other
>car.
>
>What is this disc suppose to do.
>
>In OZ leaded fuel is still readily availble, however I cannot but think that
>unleaded fuel is a problem overseas,  Unleaded is known to be less efficient,
>hence the lower mpg's and also is burn hotter.  I have heard that a cheap way
>to de-coke a car is to run it on a tank of unleaded. and burn the carbon out.
>
>Maybe this is why my other car a Triumph 2500S sedan has covered over 300,000
>kilo and never had the head off.  a Few years ago while on a long trip I
>accidently filled it with unleaded, it rattled a bit until I could get to add
>some leaded.
>
>keep staggering
>
>brian 
>___________________________________________________________________________
____
>
>At 10:02 AM 10/24/97 +1000, Brian.Tink@domain.elided wrote:
>>What's this air conditioning stuff??
>>
>>My cars come with an air-con system called  "ALL-X"
>>
>>           ALL  = all windows down and in the case of the stag top off, and
>>            X   relates to the speed in either MPH or KPH
>>
>>keep staggering
>>
>>Brian
>> <snip>
>
>Yeah, I probably won't use mine very much either, but I want it to work
>anyway (words to live by!).
>But getting back to overheating, another thought I had relates to the disk
>on the back of the mark II thermostat. After thinking about it, it seems to
>me that this disk should contact the back of the housing when the
>thermostat is installed, so that the spring pressure will only allow
>coolant flow through the bypass passage when there is high pressure (and
>which will increase as it opens). As I recall, mine did not install under
>spring pressure. If you do the math, a 1/2 open thermostat is only open
>about 1/8 inch, so it seems likely that the disk must be installed closer
>than that, at least. My version of the shop manual doesn't mention anything
>about this, but they could be assuming that a correctly manufactured part
>(and correctly machined housing) is being used! Does anyone have any better
>information?
>
>Robert Ducker