For What Its Worth

Adding SPAL electric fans

What you don't see well is the 1/4" spacers between the fan mount and the radiator flange it mounts to.  Absolutely assure the bolt heads holding the fan on will not get close to the radiator.  Also the top and bottom of the fan mount wont rub on the radiator.   Used a good weather seal to assure a tight seal around the outside.

I bought the setup used, but this looks like the fan mount sold by Chevy II Only.   I had to ream one of the radiator mount holes about a 1/4" longer and twist the mount slightly left to right to get enough clearance for top and bottom radiator hoses. You can not see it, less than 1 degree, but needed about 0.25" to clear the hoses.

Here is the outline of the wiring.

I updated the wiring in Nov 2009 to use 2 Engine Temp Switches.  One is 185 on/off  This controls one fan.  The other is 185/170 on/off for the second fan. I had a 200/180 for the second fan which never seemed to work well.  After 18 months tests revealed it was not functioning to temp spec.  I replaced it with a 185/170.

I like the mechanical switches.  Simple and redundant back up.  Both temp sensors would have to fail for both fans to fail.

Note on temperature switches and designed location.   Getting a switch to work correctly for a fan when installed at the thermostat or water neck area is key.  Many switches are designed to be put in the head.   A 195 rated switch designed for the head may turn on at 215.  Head location for a sensor is higher temp than what water temp is at a thermostat.  Many of the "head" based sensors may be adjusted to account for the difference.  Rated 195 at the thermostat may be 215 or so at the head/sensor location.   Putting sensors designed for a head in the thermostat or water neck area may lead to excessive heat before they activate.

Why not use a new electronic control?   I looked at all the high tech fan controllers that could be adjusted and control 2 fans.  The problem I had was they were cheap or sensitive to high voltage.  The better ones have to be in a safe environment, inside the car and sensor wires can not cross Ignition wires etc.  Maybe one day, but not for now.

Happy Motoring, VHubbard.  May 2009

Last update July 2, 2011

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