The way to power the fans is,, the +12V power should be from the alternator output stud, and the relay switching power should be from the ACC tab on the fuse box,, that way, the fans only run when the engine is running and the alternator is supplying power, and they do not run when the engine is cranking. You would have to avoid putting the key "on" (ACC) w/o the engine running when hot or back into the ACC position when hot. This is the safest and best wiring technique, and keeps the fans from drawing through the car wiring from the battery, which you do not want.

The older Corvette wiring was not designed to supply that much current fron the batt. You will need to run each fan ground separately, clean the area you are going to bolt it to to shinny metal with some fine sandpaper, and smear it with silicon grease. though they can share the same ground point, they must not be joined together into one wire. 20A is allot of current. you have to build the power harness strong, with very tight crimps, even soldered after crimping is better, and make sure your connections are very tight and have a good, metal area contact, at the relays and other connection points. I would say 10 gauge minimum should be ok. **also make sure your engine to frame ground cable is in good condition ie- replace it)

 

Man, I'm glad you posted that about the ground wires, because I just finished splicing them into one 8 guage wire that I was going to ground to the frame. Guess I'll cut it and start over with two wires for the ground. Thanks for the heads up.

 

One eight gauge at 40 amps actually might be ok, on 10 it would not be. no matter though, two seperate will be better.

 

Is it worth giving it a try? Will I fry my fans if it's not enough? I've already got the wires spliced together and the ground ready to be bolted to the frame, so I'd like to avoid doing all the splicing and such all over again, especially since the fans are mounted now.

 

8 gauge should be fine,, like i said, 10 would not be. did you catch my post on how to power it up? this is the best way. Keep everything short and tight and direct. relay controll from ACC tab.

 

there should be a hole with plug in it just above the fuse box in the pass compartment, you should grommit it later, but for now, you can run the wire through there.

 

I did get power from the alternator post, but I had already spliced into the yellow wiper wire for switched power. I may see how I like it set up like this, but can always go back and re-route the switched power to the ACC terminal. Thanks very much for your help...hopefully I'll report back with good results tomorrow.

 

93 yellow is fed by 12 brown which is fed by ACC. your all set.

 

Beautiful. Getting started again momentarily...hopefully I'll be finished with the fans this morning, then it's on to final paint prep. Few too many projects going on at once!

 

Dewitt's aluminum with dual spal's. You get all the directions, wiring, relays etc.

 

OK, everything is wired up and mounted. Now I just have to get up the nerve to go and start the car up and see if everything works! Fingers are crossed...

 

OK well, the only good new I have is nothing caught fire. The fans didn't come on at all. Another side problem is that my temp guage is not working, so I'm not positive how warm the motor got, but I let it idle for a good 10 minutes and randomly brought the engine up to 1500-2000rpms. The thermostat I have is 200 on, 185 off. The temp outside (and in my garage) is about 55 degrees. Did I give the engine enough time to reach 200? I know, I know, I need to get the guage fixed. The temp sending unit is good, I checked it with an ohmeter and grounded the wire to see if the guage would move, but nothing. The guage is stuck at about 165 at all times...key on, key off, engine on, engine off.

Just to recap, I have the fans wired each through a 30 amp relay. 12v constant is coming from the alternator, 12v switched from the yellow wiper wire. Both "86" wires go to the thermostat in the intake manifold. "87"s going to the fans themselves. Fans are grounded to the crossmember just behind the radiator.

Anyone see any glaring mistakes?

 

 

the eisyest way to test it is to remove the wire to the temp switch, start the car, then short it to the block metal, the fans should come on. If they don't, i would next look at the switching power from the wiper source.

If they do come on, you either didn't get the car hot enough, used teflon tape on it, or it's bad.. to start.

 

just to recap, 30 should get the feed from the alternator, 87 (not 87a) should feed the the fans, 85 should be fed by the ACC or in this case the wiper power, 86 should go to the temp switch.
Can i ask you to post a link to the temp switch you used?

 

Here's the link...

http://store.summitracing.com/partde...5&autoview=sku

And I did use teflon tape on the threads...is that bad? I was afraid it would leak if I didn't...

I'll try it out again tomorrow and see if I didn't get it warm enough.

 

You can't use teflon tape, it's an insulator. test it like i said above, it should work, that's probably your problem.


The other issue is that the thermostat close temp needs to be greater then the 'Off' temp of your thermal switch, that way, the fans regulate the temp, but there is a constant flow of coolant.

For example, if your thermostat is a 165° and the off temp of your switch is 175° that's ideal. IF your running a 185° thermostat, and the off temp of your switch is 175°, you have a problem.

Try using some anti-seize on the threads if your worried about leaks, it's goopy, but is copper infused and won't interferer with the threads biting into the metal for good electrical conduction. It's a NPT thread, so it shouldn't leak though.

 

OK, here's the update...it lives! Everything works as it should, and the fans work great. Very quiet, and cool very quickly. Highly recommend this mod to anyone thinking about it...if I can do it, then anyone can.

Thanks to everyone for all their help!