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Re: Electric Fans in LBCs

To: "Ed Woods" <fogbros@nb.net>
Subject: Re: Electric Fans in LBCs
From: "Sumner Weisman" <sweisman@gis.net>
Date: Fri, 19 Jun 1998 16:56:01 -0400
Cc: "Triumphs" <triumphs@Autox.Team.Net>
Ed,

Of course, you're correct.  The belt is on the crankshaft, as is the fan.

Regards,

Sumner

----------
> From: Ed Woods <fogbros@nb.net>
> To: Sumner Weisman <sweisman@gis.net>
> Subject: Re: Electric Fans in LBCs
> Date: Friday, June 19, 1998 9:12 AM
> 
> Hi Sumner,
> 
> Thanks for your reply; but I'm curious to find out what belt on a TR3
drives
> a fan?? Was your car modified or are you so happy with the electric that
you
> forgot the original 4 blade attached to the crankshaft??
> 
> Ed
> -----Original Message-----
> From: Sumner Weisman <sweisman@gis.net>
> To: Triumphs <triumphs@autox.team.net>
> Date: Thursday, June 18, 1998 7:05 PM
> Subject: Fw: Electric Fans in LBCs
> 
> 
> >
> >
> >
> >----------
> >> From: Sumner Weisman <sweisman@gis.net>
> >> To: Ed Woods <fogbros@nb.net>
> >> Subject: Re: Electric Fans in LBCs
> >> Date: Thursday, June 18, 1998 7:01 PM
> >>
> >> Hi Ed,
> >>
> >> You didn't miss too much.  Some folks felt strongly that the standard
> >> belt-driven fan is perfectly adequate if the radiator is clean and
> >proper.
> >> Others put larger belt driven fans on with more blades (4 blade TR-4
fan
> >> instead of 3 blade TR-3 fan), etc.  Others felt the current drain of
the
> >> fan was excessive for the LBC wiring system.
> >>
> >> My experience has been very positive.  I used to have SERIOUS
overheating
> >> problems with the TR-3, especially when stuck in heavy traffic in the
> >> summer, and a couple of times it overheated so badly that I was afraid
of
> >> warping the head.  I mounted a 12 inch fan on the front of the
radiator,
> >> with its own adjustable thermostat on the fender well.  I left the old
> >belt
> >> driven fan in there, and the new one just comes on and supplements it
> >when
> >> necessary.  Since putting it in, my overheat problem is gone!  The
> >> temperature gage pointer sits on 185 degrees, like it was painted on.
> >> Never goes above.  I love it.
> >>
> >> Regards,
> >>
> >> Sumner
> >>
> >> ----------
> >> > From: Ed Woods <fogbros@nb.net>
> >> > To: Sumner Weisman <sweisman@gis.net>
> >> > Subject: Re: Electric Fans in LBCs
> >> > Date: Thursday, June 18, 1998 9:18 AM
> >> >
> >> > Sumner,
> >> >
> >> > I wasn't on the list during the fan thread. Could you give me more
info
> >> on
> >> > what you've installed. I'm going to go that route on the TR3 I've
just
> >> > started on.
> >> >
> >> > My '60 is running a TR250 fan, mounted backwards. A bolt on fit that
> >> works
> >> > well though I haven't been able to convince anyone that that big
> >yellow,
> >> > plastic fan is original equipment!!
> >> >
> >> > Thanks,
> >> >
> >> > Ed Woods
> >> > -----Original Message-----
> >> > From: Sumner Weisman <sweisman@gis.net>
> >> > To: Triumphs <triumphs@autox.team.net>
> >> > Date: Thursday, June 18, 1998 8:58 AM
> >> > Subject: Electric Fans in LBCs
> >> >
> >> >
> >> > >
> >> > >Hello Listers,
> >> > >
> >> > >I am the culprit who started the weeklong thread on electric fans a
> >> couple
> >> > >of months ago.  I certainly don't wish to get into all that again
-- I
> >> > >respect all of your opinions, and have mine as well.
> >> > >
> >> > >After a number of off-line conversations with people who want to
> >install
> >> > >one, I thought this note and wiring tip to the list might be
helpful.
> >> > >
> >> > >I installed a fan with a separate adjustable thermostat.  That way,
> >the
> >> fan
> >> > >runs only when it needs to run, after the water temperature exceeds
> >the
> >> > >setting of the thermostat set point.  The thermostat also has some
> >> built-in
> >> > >hysteresis, so that it keeps the fan running until the water is
cooler
> >> than
> >> > >the setpoint temperature.  Otherwise, the thermostat contacts would
> >> > >"chatter" when the setpoint temperature is reached.
> >> > >
> >> > >Initially, I wired it to a "hot" circuit that was powered all the
> >time.
> >> > >(The fan has its own in-line fuse.)  That way, I reasoned, the fan
> >would
> >> > >keep running after I shut the engine down, (like some German cars
do)
> >> until
> >> > >the engine was cool.  That worked as planned, but it ran for such a
> >long
> >> > >time, without the generator charging the battery, that the battery
was
> >> > >always partially discharged.  Not a good idea.
> >> > >
> >> > >Therefore, I rewired it and connected the hot side to the
"switched"
> >> side
> >> > >of the ignition switch, so that the fan would not run after the car
> >was
> >> > >shut off.  That introduces another possible problem.  The fan motor
is
> >> an
> >> > >inductive load, not resistive.  An inductive load, when switch off,
> >> > >generates an inductive "kick" that tries to keep the current
flowing
> >in
> >> the
> >> > >same direction as before.  This inductive "kick" is a large voltage
> >> spike
> >> > >that can pit the ignition switch contacts.  The simplest way to
> >> eliminate
> >> > >this problem is to wire, in series with the hot side, a silicon
diode.
> >
> >> It
> >> > >is wired such that the diode is forward biased when the fan is on.
> >> (Anode
> >> > >to power source.)  When the large voltage spike occurs (when you
turn
> >> off
> >> > >the ignition switch) it reverse biases the diode, effectively
> >> disconnecting
> >> > >the ignition switch from the fan.  Problem solved.
> >> > >
> >> > >I also wired in a dash-mounted switch to turn on the fan manually,
if
> >> > >needed, in case the thermostat ever failed.
> >> > >
> >> > >This system has been in place for over a year with no problems, and
I
> >am
> >> > >very satisfied with the results.
> >> > >
> >> > >Sumner Weisman
> >> > >62 TR-3B
> >> >
> 

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