Put a clutch fan on her today and she ran 215 degrees on an average driving and when I got on her a little bit on the highway ..... she raised to 225 for just a few minutes and then came back down to 215 .

I have her under control now so to spreak , but I really figured she would run a lot cooler with the 4 flew radiator thats in it now .

 

Must be a heating and cooling contractor....

Make sure all the seals are in place between the rad and cradle and between the cradle and fan shroud. Also, make sure your timing is right....I've seen that heat up a few motors. Are you running a high volume high pressure oil pump? If so you might need an oil cooler...just my 2 cents.

 

Yes , I do have a high volume oil pump installed ..... thanks ! The Timming , I still need to play with a little .

 

I swapped my radiator for a DeWitts with dual SPAL fans. My 500HP 408 stroker motor never runs over 180. How much more cooling do you need??

 

You don't need electric fans. They do work great and no matter what radiator you have, more air will increase the btu rating. With that said, fans are not your porblem. The radiator for an 81 is plenty large enough. I have the stock unit in my 80 and I never go over 180, ever.

The correct radiator term is "row". IE 3 row or 4 row. Even the useage of 4 core is wrong. The core is the whole center assembly consisting of tubes, headers, and fin.

No C3 past 72 came with aluminum. All 73-82 Corvettes used copper brass ONLY. We discussed that before but someone keeps throwing that in there.

I would get an infrared gun first thing, and confirm what your gauge is telling you. Many times people chase a problem they don't really have because they are only using the guage as their source of information. A lot of the replacement sending units read bad and usually to high. Check that out first.

Are you running a 50/50 mix? Some believe that running straight anti freeze is a good idea and it will run about 20 degree hotter than a 50/50mix.

I'm not a big believer of the "air in the system" theory, but for the sake of an easy test. Remove the thermostat and run it without one for a while. If the problem goes away, put it back in and see what that does.

The "new" water pump could be bad or the wrong size. I've had many people tell me that they actually ran hotter with a high flow water pump. The pump needs to be matched to the radiator for it to work at peek performance. So, in your case a higher flow might actually help because you doubled the coolant flow path by changing from a 2 row to a 4 row.

If in the end, nothing ends up working an electric fan would reduce the temps and/or changing to the aluminum radiator. But you shouldn't need to do either.

 

Some VERY good points. As simple as it all seems ....it's probably some small change that will fix it. As far as 4 flew(for you Tom...lol)...that should be adequate with a stock system. As Tom implied...stock gauges are notoriuosly bad. As previously mentioned, an electric fan will probably eliminate all you problems. I might have a fan for you. A Lincoln Mark 8 fan. That means getting rid of the stock fan shroud.

 

I had a similar problem, but resolved it by going to a DeWitts Aluminum. The original Radiator (4 flews/rows) that I replaced about 6 years ago, cooled very good, but I had to have leaks fixed every couple of years. I bought a replacement, same size and 4 flews/rows, don't remember from where, and it never cooled as good as the original. When I pulled it out to install the Aluminum, I did a side by side comparison with the original radiator, and noticed the one that did not cool as well, had less density in the brass fins that are between the tubes to disipate the heat, than was on the original.

 

Thanks guys , I appreciate all the input .

Batman , dont be mad at me , I just had to throw that little joke in for a little humor .

I really do appreciate all you guys very much so !

 

Was the "before" run in July?

 

thanks for the injection of common sense .

i did have an air up after replacing heads once. if it happens, you'll generally know it because it won't want to stop at 220 - just my experience, your mileage may vary.

 

Try replacing the themostat with a high quality one.

 

What before run ?

The engine was just installed this month .... yes .

 

I never really stopped and thought of an incorrect reading guage but your probably correct because it has not attempted to boil over .
I backed the timming down today a couple of degrees and it seemed to help a little . Guage is showing 210 on an average today . The Pinging lightened up too .

 

For what It's worth. I bought an Edelbrock water pump because I thought it would be better, and look cooler. But in fact it made the engine run 15 degrees hotter. I figured it was moving the coolant through the radiator faster, not giving it as much of a chance to cool down. The radiator was flushed and tested before hand. I put the original one back on, and it cooled right down where it should be, 190. But, because the Edelbrock looked better I put it back on. Now it runs about 200-205. I'm comfortable with that. Try the original, you might like it.
TJ

 

Then you obviously have not experienced a dual Spal setup!

 

Obviously !

 

was the same coolant transferred? or did u use a new mix?
water runs about 20F cooler than 50/50

 

Yes , same coolant .... New engine ... new coolant .... everything NEW ! $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

 

What Radiator is the 4-row? aftermarket? local radiator shoppe?

{anecdotal}

I remember last summer I was out cruising with Jeff Smith (tech editor Car Craft) and he related a story to me about cheap radiators (both brass and alum) with excessive spacing between core tubes...now this discussion was almost a whole year ago and I do think he wrote an article about this since.

Basicly though... it boiled down to a bunch of cheap rads that while they may have 4 rows...those rows are spaced further apart than say your factory radiator. IIRC and I'm sure Tom can correct me if I'm wrong... alum. rqad usually have larger tubes at maybe a slightly greater spacing than the factory brass ones..but since the alum transfers the heat so much more effectively this is ok. - however if you bought a cheap copper/brass one with increased spacing between tubes you might not be as efficient as a fewer row but denser spaced radiator.

I dont have a copy of the article, and I'm sure there is someone here who either does or simply knows about this in detail - compared to my faulty 1 year memory

If you still have your old rad - take a look at it from head on shining a light through it .. and then do the same with the new one...

{/anecdotal}

 

put the 2 row back in.
less weight; more cooling
.
not the 1st time a more $$$ part worked worse.