carb converted 85 c4- fan ?
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Heel & Toe
Joined: Nov 2007
Posts: 16
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carb converted 85 c4- fan ?
my first post on this forum...
i converted my 85 c4 to carb...it runs well.
what must i do to have the fan operate, i looked at the shop manual and grounded the green/white wire. fan does operate, so relay is good...what am i missing ?
many thanks in advance.
raf
i converted my 85 c4 to carb...it runs well.
what must i do to have the fan operate, i looked at the shop manual and grounded the green/white wire. fan does operate, so relay is good...what am i missing ?
many thanks in advance.
raf
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Joined: Jun 1999
Posts: 14,924
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From: Merritt Ils Fl
I assume you mean the green and white wire going to the sensor between plugs 6 and 8. If I recall, that sensor doesn't turn on the fan until temp hits 228 or so. You can buy lower temp sensors from most Vette parts suppliers.
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From: The Top of Utah
Originally Posted by Muffin
I assume you mean the green and white wire going to the sensor between plugs 6 and 8. If I recall, that sensor doesn't turn on the fan until temp hits 228 or so. You can buy lower temp sensors from most Vette parts suppliers.
What is missing is the ECM that used to ground that green/white wire to run your main fan. You will have to devise an alternative way to ground that wire. You can use a manual toggle switch or even a thermal switch like used for the aux fan.
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Race Director
Joined: May 2006
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From: Phoenix Arizona
Or just ground the green/white wire. That causes the fan to run when you turn the ignition on. That's what we do regularly on the 84-89's down here anyway. (It's hot enough here not to cause a problem, and it tends to keep the car a liitle cooler in city usage)
Team Owner
Joined: May 2002
Posts: 24,337
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Just add a coolant temp switch rated somewhere around 210F. Wire this directly to the green relay wire and you'll have fan control when you need it. If you have 2 fans, the second one has a 238F switch. They should be staged, the 2nd fan is pretty much useless anyways. I wouldn't want them on all the time, too much noise, and it's pointlessly wearing out your fan motor anytime the thermostat is shut.
Are you keeping A/C? that has a high pressure switch that also needs to feed the fan relay.
Are you keeping A/C? that has a high pressure switch that also needs to feed the fan relay.
Burning Brakes
Joined: Sep 2006
Posts: 1,142
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From: Spring Grove Illinois
I installed a 180 temp thermo switch that replaced the stock one and a relay to turn the fan on and off @ 180.....The ECM does in fact control the fan...WELCOME TO THE "DARK SIDE"
Last edited by Happydad; Dec 16, 2007 at 07:58 AM. Reason: my spelng sucz
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Thread Starter
Heel & Toe
Joined: Nov 2007
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using a edelbrock performer intake,
edelbrock 1406 carb,
edelbrock 1221 air breather drop base & 2 inch high 14 inch round filter
using mallory bypass fuel regulator
still have not touched the 700r4, torque converter lock up, but will take care of asap
right now i just want to get the engine up & running...it has been down for two years, had my engine professionally remanufactured, also tranny while apart...wiring is problematic(old & brittle)
i believe in efi, but also believe in my wallet...
thanks for all the help...
raf
edelbrock 1406 carb,
edelbrock 1221 air breather drop base & 2 inch high 14 inch round filter
using mallory bypass fuel regulator
still have not touched the 700r4, torque converter lock up, but will take care of asap
right now i just want to get the engine up & running...it has been down for two years, had my engine professionally remanufactured, also tranny while apart...wiring is problematic(old & brittle)
i believe in efi, but also believe in my wallet...
thanks for all the help...
raf
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
The SWITCH "between plugs 6 and 8" is for the auxiliary fan, or if there isn't an aux fan it is a back up to the ECM which operates the main fan.
What is missing is the ECM that used to ground that green/white wire to run your main fan. You will have to devise an alternative way to ground that wire. You can use a manual toggle switch or even a thermal switch like used for the aux fan.
RACE ON!!!
What is missing is the ECM that used to ground that green/white wire to run your main fan. You will have to devise an alternative way to ground that wire. You can use a manual toggle switch or even a thermal switch like used for the aux fan.
RACE ON!!!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by Muffin
OK I'll agree it is a SWITCH but my FSM shows the SWITCH will, when a temp of 238 degreesis reached, turn on the fan. When the A/C is turned on the ECM will turn on the fan no matter what the coolant temp.
1.) If the car has an auxiliary fan, the aux fan will run when the fan switch closes at 238°. The main fan will never run.
2.) If the car does not have an aux fan, the fan switch, which backs up the ECM, will turn the main fan at 238°.
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Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by CenteralCoaster
3.) Neither fan will come on when your a/c head pressures are too high.
4.) You will overheat, guaranteed.
4.) You will overheat, guaranteed.
And if the Summit switch is too expensive, like most of the Corvette specialists are, go to a parts store and buy a stock switch that is physically the same, but with lower temps. Then replace the stock fan switch in the right head and wire it to ground the primary side of the main fan relay as the ECM used to. If you like, while you are wiring, you can run a pair of wires into a toggle switch in the cockpit for additional manual control.
I strongly advise against using a switch with a 180°, or close, on temp. That will cause the fan to run too much, probably constantly. That only burns up fan motors and wastes gasoline.
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Team Owner
Joined: May 2002
Posts: 24,337
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Yes, with a 180 stat, ideally you want the fan to shut off around 195 or so.
This means the engine will operate happily between 185-195F, and the fan OR thermostat (and not both at the same time) will modulate on/off open/close to keep the car in that temp range.
This also means your fan on temp need to be about 15 degrees above that 195, this is built into the switch usually. Visualize what would happen if the fan came on at 210 and off at 208, it'd cycle every 10 seconds.
And my experience is a 180F standard tstat is usually more like a 185, and the same rated high flow tstat is more like a 175.
This means the engine will operate happily between 185-195F, and the fan OR thermostat (and not both at the same time) will modulate on/off open/close to keep the car in that temp range.
This also means your fan on temp need to be about 15 degrees above that 195, this is built into the switch usually. Visualize what would happen if the fan came on at 210 and off at 208, it'd cycle every 10 seconds.
And my experience is a 180F standard tstat is usually more like a 185, and the same rated high flow tstat is more like a 175.
Burning Brakes
Joined: Sep 2006
Posts: 1,142
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From: Spring Grove Illinois
[QUOTE=CentralCoaster;1563216310]Yes, with a 180 stat, ideally you want the fan to shut off around 195 or so.
This means the engine will operate happily between 185-195F, and the fan OR thermostat (and not both at the same time) will modulate on/off open/close to keep the car in that temp range.
Yepper
That's what mine does...No issues and it keeps the engine cool...Worth the $$$ no switch to forget to turn on..no fans running constently...Pretty much like factory...Mount the relays install the sensor and go
This means the engine will operate happily between 185-195F, and the fan OR thermostat (and not both at the same time) will modulate on/off open/close to keep the car in that temp range.
Yepper
That's what mine does...No issues and it keeps the engine cool...Worth the $$$ no switch to forget to turn on..no fans running constently...Pretty much like factory...Mount the relays install the sensor and go
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
The relays are already there. Just hook up the new thermal switch and you are done. My suggestion for the toggle switch was as an add on. I use mine between rounds at the drag strip. I have a 180° thermostat and my fan comes on (via thermal switch) at 206° and off at 196°. It only runs in stop and go traffic. Depending on the ambient temps I cruise between 178° and 188°.
RACE ON!!!
RACE ON!!!