Radiator Shroud Extension

[Jack H.]

Re: Radiator Shroud Extension

BELIEVE the red zone band on your temp gauge! That's why designers put it where it is. If your temp system is accurate, then you're 'safe' when you're hot but still below the red zone...

You'll note as the Shark era progressed and more emission control features were added, the red zone climbed upward (260F, Etc.). That's because underhood temps increased in lock-step.

Look at where the danger zone is on your current daily driver. You might be surprised to see it pushing 300F. The inherent 'fear' of running too hot, is something that's 'normal' among those new to the care and feeding of these classic cars.

They tend to be 'gun shy' of anything that's above 160-180F and lack the actual driving experience with the profile these cars had when they were factory fresh/new. They know the engine's been overhauled and they're on a hair trigger to seeing the temp gauge climb above it's 'normal' range.

Today, we have MUCH more accurate temperature reporting systems on board + engines are designed with a myraid of compensating systems such as automatically switched electric aux fans. So, our daily drivers don't exhibit as much coolant temp variance as the old/classic cars did. But, that's the nature of the beast!

Bottom line, if you're in grid lock/stop-go traffic on a hot day and you see your temp gauge rising, you CAN compensate! Manually do what the TCS/CEC system did and simply put a little 'foot' on the gas to boost engine RPM and pull more air through the radiator. You don't have to sit and wait to see if she's really going to boil over with a geyser of underhood coolant!

[Joe L.]

Re: Radiator Shroud Extension

Yes, in fact I have taken that advice for 2 reasons; most here have a much greater knowlege of these cars and most of the TCS components are long gone.

Interesting to hear that 220-230 isn't an over the top temp. In fact the red zone on my temp guage is very close to 250, perhaps exactly at 245.

Any thoughts on the fan blade? Thanks!

Lynn------


The correct fan blade (with the unusual tip configuration) is mostly a judging advantage. There are other fan blades that will cool as well or better. If your car is a 1971 or later, a GM #342715 is one of these.

The installation of the shroud extension will improve cooling but only marginally. You probably would not notice the difference.

On the other hand, proper sealing of the shroud to the radiator and the radiator to the support is CRITICAL. You can expect cooling problems under low speed conditions in high ambient temps if the sealing is not as it should be.

[Terry M.]

Re: Radiator Shroud Extension

Lynn------


The correct fan blade (with the unusual tip configuration) is mostly a judging advantage. There are other fan blades that will cool as well or better. If your car is a 1971 or later, a GM #342715 is one of these.

The installation of the shroud extension will improve cooling but only marginally. You probably would not notice the difference.

On the other hand, proper sealing of the shroud to the radiator and the radiator to the support is CRITICAL. You can expect cooling problems under low speed conditions in high ambient temps if the sealing is not as it should be.

Joe,

Your usual advice is that "the Chevrolet engineers didn't build it that way because another way is just as good." Are you saying the pointy fan (with shims on the engine mounts to center it) and the shroud extension are really not necessary to effective cooling?

[Joe L.]

Re: Radiator Shroud Extension

Joe,

Your usual advice is that "the Chevrolet engineers didn't build it that way because another way is just as good." Are you saying the pointy fan (with shims on the engine mounts to center it) and the shroud extension are really not necessary to effective cooling?

Terry------


The main purpose of the tip design was noise reduction.

The last year of use for the "pointed tip" (GM #3992095) fan was 1973 big blocks with C-60 and I'm not even sure that all 1973's got it.

Although it did not OFFICIALLY supercede the "pointed tip" fan for SERVICE, the GM #342715 was used for all 1974-76 applications with C-60. So, effectively, "GM didn't come up with the 342715 fan blade assembly because the 3992095 worked just as good". Used with a GM #343721 (now 88961768) fan clutch, there's no better cooling combination EVER used on a Corvette. Period. Even with an original style 71-73 fan clutch it will at least equal the cooling performance of the "pointed tip" fan.

The 342715/343721 combination will be a bit noisy. However, that noise should be "music to the ears" when stuck in slow speed traffic on a hot day.

[Terry M.]

Re: Radiator Shroud Extension

Well, I do agree the 343721 is the bomb, but I thought the fan points were to suck the last little bit of air through the radiator. Noise reduction makes sense however. Like you I appreciate the "noise" of a working fan clutch.

[Tom L.]

Re: Radiator Shroud Extension

Thanks for the clarification. One thing for sure is that the fan you mention is the one Im using and it IS noisy. My trip to carlisle at 70MPH was brutal on the ears, they were ringing after I got out of the car. If the blade will functionally do the job of the tipped blade then fine, I'll still be looking for one so I don't have to wear ear plugs on long trips.


Thanks!!

[Joe L.]

Re: Radiator Shroud Extension

Thanks for the clarification. One thing for sure is that the fan you mention is the one Im using and it IS noisy. My trip to carlisle at 70MPH was brutal on the ears, they were ringing after I got out of the car. If the blade will functionally do the job of the tipped blade then fine, I'll still be looking for one so I don't have to wear ear plugs on long trips.




Thanks!!

Lynn-----

While the correct fan (with "spiked" tips) will MARGINALLY reduce fan noise, I doubt that you'll even notice the difference.