Get WiredQ I have an '04 two-wheel-drive pickup with a 5.3L V-8, auto trans, and A/C. I've purchased the electric fans from a local dealer for an '05 pickup. Each motor has two white wires. Does the wiring harness for an '04 truck have the wires built in for the proper hookup for these fans? If so, which ones? Is there a color-coded wiring diagram I can get? Or will I need to buy an aftermarket fan-relay wiring kit?Jim Robinson
A The electric fan option started in '05 on 1500-series pickups, so the factory harness doesn't have the wiring in it for your fan assemblies. But aren't those fans the coolest things you've seen in a while? It's hard to beat a factory-engineered cooling system that will move enough air to cool your truck in the dead of summer.
The best thing I can suggest is to pick up an aftermarket electric cooling fan system from Painless Wiring, which offers a very nice adjustable cooling fan thermostat and relay assembly. This thermostat will control the fan operations from 32 degrees F all the way up to 248 degrees F. Since you have the dual-cooling fan assembly, I would wire it with dual thermostats so you can have a high and low cooling fan, just like the factory. Set one fan to come on slightly earlier than the other. You will be surprised how little the high-temp fan will come on. The Adjustable Thermostat Kit is sold under PN 30104.
Make sure when you wire those fans they're blowing in the right direction. With two white wires, we can't be much help in the wiring. Ken Casey at Burt Chevy looked up the '05 truck wiring for me: The harness uses a light blue wire for the power and black for the ground. This must be the power wires in the harness, not the wires to the electric motors of the fan. Remember, electricity is a theory-you can't see it!
Exhaust Temp BoogieQ I drag-race a '68 396 Camaro. I recently installed a clamp-type temperature meter in the No. 5 cylinder and had a reading of 1,285 degrees. I jetted the carb down until it read 1,378 and was happy with the performance gain. Then I placed the probe in the No. 1 cylinder and it read 1,509 degrees! I've always jetted one size larger in the primaries than the secondaries, and I tried jetting the primaries up without touching the secondaries, using 89s in the front, to get the temp down to 1,420. I then placed the probe back in the No. 5 and got 1,295. After down-jetting the secondaries to 77s it read 1,320. I ran out of time to mess with it and raced. With each adjustment I picked up mph and dropped e.t., so the engine seemed to like it. The car is consistent, but this temperature spread bugs me and I'd like to know what kind of spread you've seen between cylinders, front to back, and what you did to compensate.Johannes Berndt
A Sounds like you've been chasing exhaust-gas temperatures based on your EGT meter instructions saying you should have 1,350-degree temperature. You aren't the first and you won't be the last.
There is no correct exhaust-gas temp for any engine. Each one will produce its own temperatures based on its combustion efficiency, affected by just about everything, including the cylinder-to-cylinder fuel distribution as per the inlet-manifold runners and the good and bad inlet ports in a big-block cylinder head. A poorly designed header tube on a cylinder will leave more residual exhaust gas in the cylinder after each exhaust stroke. This cannot burn a second time and will affect the power output of that cylinder and the heat it produces. Even the way the lifter bores are machined in the block will cause variation in cam timing from cylinder to cylinder. I could go on for days, but I think you get the point.