Hi John,
You have probably covered these things but; you have not mentioned the
radiator ducting on your message. We have found that is imperative the
air intake deflectors are correctly installed to prevent air which has
passed through the radiator from circling around the sides and
re-entering the front of the radiator particularly when the car is
stationary.
Although there has been considerable discussion about sleeved
thermostats helping to keep the engine temperature down we have always
been able to achieve perfectly satisfactory cooling using standard
thermostats and fans when the cooling system is in good condition, other
than the occasional burp if you are forced to come to a stop suddenly on
a very hot day after driving for a while at high throttle.
Of course we don't have any hills of consequence here in Ontario so I
cannot vouch for hill climbing ability.
It is interesting to note that the factory specified 182 degree
thermostats from the MkII on to improve the effectiveness of the heater.
I would very much doubt that they would have done this if overheating
was an ongoing problem on new cars.
I definitely agree with other listers who have advised against bending
the fan blades, I have seen the results of blades flying off as a result
of cracks and you don't want to go there.
One other thing regarding the timing check. Have you confirmed that the
timing advances fully when you rev the engine up? With the vacuum
advance disconnected the timing should be around 34 BTDC at 4 - 4500
RPM.
Michael Salter
www.precisionsportscar.com
> Hello List,
>
> I have a problem w/ both of my recently restored tri-carb Healeys.
One is
a
> BN7 (2500 miles), and the other is a BT7 (1500 miles). Both overheat
very
> quickly when idling in neutral. Both had a complete overhaul of the
engines,
> both have new radiator cores (4 staggered rows of tubes, like the
factory
> original). I also have an original, unrestored BT7 MK1 (head has
never
been
> off, radiator has never been rodded, has over 100,000 miles) that does
not
> have this problem. Have owned this car for over 34 years.
>
> Currently working on the BT7. Timing is right on, checked the
clearance
> between the water pump impeller and the housing, richened the fuel
mixture.
> Took it for a drive on a deserted road at 30 mph, 4th gear, o'd, 3.54
axle,
> about 1200 rpm. Ran cool, right on the thermostat. Stopped, put in
neutral,
> but kept the engine at 1200 rpm. Started to overheat immediately.
Started
> driving w/ same settings, and trmperature stabilized, and then started
to
cool
> down. Clearly the problem is air flow. The car has a standard fan,
and I
> really don't want to go to a Texas Cooler as I would like to keep the
engine
> original looking.
>
> Question: Has anyone tried changing the pitch of the fan blades? I
am
temped
> to try this, but it could be a really big mistake. Won't try it
unless
> someone out there has had success and can tell me just how far to bend
them.
> Maybe this is a Really Dumb Idea, but had to ask.
>
> TIA
>
> John Snyder
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