Ashford, here is a thought as it relates to the hood being open vs. closed
and the temperature rising.
With the hood open the fan is able to gather cooler air and force it past
the radiator. With the hood closed it may well be re-circulating the hot
air of the engine compartment only. Do you have a shroud installed? If yes
that would tend to negate my idea. If not you may try adding one. In a prior
life I was involved with the design of sealing systems to prevent the
recirculation of air through a radiator for the exact same reasons that you
are describing. In our case the cars (Ford) were using puller fans but for
this argument I don't think it matters, I however would recommend that you
change to a puller setup. In general terms it's my opinion that greater
cooling is obtained, especially as you drive the car and get the ram effect
unobstructed by the pusher style fan setup.
I too have eliminated my 4A engine driven fan and replaced it with a puller
electric fan. At idle in traffic on hot days and before the electronics kick
in to start the fan I experience excessive under hood temperatures resulting
in vapor lock. I often do a manual over-ride to start the fan early for this
reason. At idle that engine driven fan moves a lot of hot air away from the
engine compartment before the engine has a chance to overheat. With an
electric fan which only comes on once the water gets to a certain
temperature allows a lot of heat to accumulate under the hood. That heat is
soaked up by every component under the hood and especially the aluminum
carburetors which are conveniently located just above the very hot exhaust
manifold.
I have high expectations for Joe Alexander's fancy dandy Heat Shield. I
think it will improve my situation quite well.
JVV
----- Original Message -----
From: "R. Ashford Little II" <70TR6@mindspring.com>
To: "6pack" <6pack@autox.team.net>; "Triumph Email List"
<Triumphs@autox.team.net>
Sent: Sunday, September 25, 2005 12:01 PM
Subject: Not quite overheating, but...
> I am experiencing an issue that I once again am calling upon the list for
a
> solution. Heres the situation. I have modified my TR6 with the
following
> recently:
>
>
>
> 9.5:1 or so head
>
> 16 Perma-cool fan used as a pusher original mechanical fan removed.
>
> Copper head gasket
>
>
>
> If I start up the car and let it idle in the driveway with the hood up
then
> the temperature gauge remains exactly in the middle and never moves.
> However if I close the hood and let the car remain idling then the temp
> gauge climbs upwards towards the > range.
>
>
>
> The outside temperature currently is 75F so its not exactly broiling hot.
>
>
>
> I did check the timing and it is set at 8-10 BTDC.
>
>
>
> Ideas?
>
>
>
> Thanks,
>
>
>
> R. Ashford Little II
|