My 75 Coupe always seemed to run a bit hot – the warmer it was outside, or the faster I drove, the temperature would keep climbing. When I added Vintage Air’s A/C, the temperature would jump another 10 degrees when it was turned on. I added a fan on the front of the radiator that was controlled by both the A/C pressure as well as the Holley EFI, but I was never satisfied that the engine ran cool enough to handle a vary warm day. The additional electric fan would only slow the increasing temperature climb. I should mention that when I got the car, someone had replaced the stock clutch-fan with a flex fan. This did not really fit the shroud opening very well.

I finally bought a 3300 CFM fan with shroud by Flex-A-Lite. This is a generic setup not specifically designed for the Corvette radiator, but the dimensions were close to what would fit my radiator.

One issue I have faced in the past was getting the original shroud out past the suspension and lower radiator hose. I have had to pull this engine a number of times, and I found the easiest way was to pull the core-support, radiator, and shroud all together. I understand that others have been able to get the shroud out by removing the top core-support bolts and leaning it forward, but this didn’t seem to work for me.

Since I did not need the original fan shroud, and it had previous damage to it (which I had patched), I ended up cutting it in 5 pieces in order to get it out.

The new shroud had two nuts embedded in each of the four sides, and came with six aluminum brackets to adapt it to the specific car. I ended up making my own brackets on the shroud and attaching these to the original brackets on the car.

One additional advantage to this setup is that I can now easily remove the radiator without all the clearance issues that the original shroud had.

I set the cut-on temperature to 196 and the cut-off temperature to 186 degrees via. the Holley EFI. I left the A/C fan in place and set it to come on at 206 and off at 196. It will also come on when the A/C pressures reach the appropriate point.

On the test drive on a high-eighty degree day, the engine temperature slowly climbed to 196, the fan kicked on, and the temperature quickly dropped to 188 and stayed there for the rest of the run.

I think I have finally found the way to keep the engine temperature at a reasonable level.

So putting a fan shroud back in solved the overheating problem or am I missing something?

1973 L-82 4 spd

Hi, You don't mention any change of the thermostat. What degree is it? Perhaps installed up side down? Are the foam pieces still in the sides, top and bottom of the radiator?  How bout the impeller on the water pump not spinning correctly?  Just curious. 

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From what I read...stock shroud assy was removed completely. The new electric fan set-up has a built in shroud specifically for the fans. Apparently with this set-up, the temps seem to be controlled appropriately by the fans, and the on/off temps he has set them for.

He doesn't really state what temps he was seeing with the fan(s)/shroud set-up he had before, other than state it ran hotter than he wanted it to....or thought it should. Sounds like you got a good set-up installed now tho, Bill! Congrats, and thanks for sharing the install notes.

Joel Adams
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Yes, Joel, you got it right.

No changes were made to the water pump or thermostat, which was a 180 degree one.

Some changes I had made in the past was to add the bottom air dam, and foam insulation around the radiator where it had deteriorated.

Even though the original shroud fit well at the radiator, the fit around the flex fan was not good at all.

I don't remember the exact temperatures that it used to get to, but I know it went above 235 on the highway before I slowed down to keep the temp down.  I assumed that on a 100+ degree day that the temperature would not be controllable.  (I know that NASCAR engines run at 290 degrees, but that's at 100 psi water pressures with very robust engines.)

I was very pleased to see the engine cool down so suddenly when this new fan/shroud turned on.  I'll have to see how it does in the summer with the A/C on. . .

Nicely done.

I had been struggling with overheating on "BLKBRRD" after installing the TBEFI setup.  Last fall took it to a shop that was a distributor/installer of the brand and they found I had routed the fuel tank vent line incorrectly which was causing a rich condition and the computer was over compensating for.  The leaning out of the fuel mixture was causing the engine to run hot.  Totally unrelated to the cooling system. 

Jim Olson 

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