My streetrod only has one opening on the intake manifold for a temp sending unit. If I use that one for the temp gauge, I don't have another for the electric fan. What can I do? I have a 350 chevy. Any ideas would be appreciated.
They make waternecks (where the radiator hose connects) with temp gauge holes in them. Im not sure if they make pretty ones but Ive used cast ones in the past
you wouldn't want a radiator fan sensor in your engine, it would always run when the motor got up to temp.
i used a short piece of exhaust pipe in my lower radiator hose. i welded half of a 3/8 pipe coupling in it for the fan sensor. also weld on a ground stud to ground the tubing and sensor.
my thoughts for using the lower hose? i figured to let the radiator do it's job cooling coolant, if it comes out too hot; then turn the fan on.
if you put in the thermostat housing or the upper hose, your fan will run as soon as the thermostat opens. even if there is ice in your radiator.
Thanks, guys for all the great advice. If I use a sensor on one of the cylinder heads, what temp sensor should I get? If this setup will indicate hotter, should I go with a 190 degree? With the sensor on the lower hose, like Ogre suggested, would the temp sensor be of a lower rate, say 180 degrees?
I use a 195* switch in the passenger head and a180* Robert Shaw high flow thermostat in the manifold. The thermo. keeps the water at 185* until it needs some cooling and then it cycles off, only on when needed.
On the last system I designed (small block Ford) I put it in the water passage on the intake. It's been a while but I think I used a fan-stat from a chrysler application. It came on much cooler than the Ford and Chevy ones.
Your engine temp at the manifold will run at the thermostat temp (e.g., 195) or about 5 degrees higher (195-200) if everything is working right. You want the fan to kick in if it gets to about 5-10 degrees higher than the thermostat temp, and to kick off when it gets about 5-10 degrees lower than the thermostat. With a 195 thermostat I think I would have the fan kick in at 200 and turn off again at about 185.
I've run my temp sensor mounted on the passenger side head fitting and on the intake manifold, and did not find a lot of difference in measured temp. I think the measured was always within about 5 degrees.
Bruce
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