Good afternoon! I got my '61 started the other day and it runs great - except for the cooling. It gets up to about 220 degrees while idling. I have read several posts about this and want to ensure I do the right thing.


First off - I would LOVE to buy the Dewitt's aluminum radiator, but it's not currently in the budget. Also, I have read where there should be no gaps in the fan shroud. As you can see in the pictures, I definitely have gaps. The question is, what is the best filler for those? Do I have to buy a kit specifically designed for these (this car is not NCRS) or is there an effective alternative?


I've also read that the fan should be situated inside the fan shroud, but I only have about 1 inch between the fan clutch and the sway bar. How for should it be inside?


Lastly, I have considered putting a 14" electric fan on the inside of the radiator. Will that work? I'm not sure how it will interact with the steel fan, which I would like to leave on the car.


I'm giving this car back to my Dad next month and want to ensure he does not have any major issues with it. Any advice would be greatly appreciated!


Jim

 

Your fan needs to be half in, half out of the shroud to work properly. You can also seal the gaps in the shroud with high density foam or asphalt sheeting. You can eliminate the clutch and run a straight fan, which will pull more air. You can run a 5 or 7 blade fan....7 blade is better. I bought a DeWitts for my own '61, and I didn't want to, either. Some things you just can't skimp on, though, and the radiator is a huge one. Take care of the obvious things, and if it still runs hot, start saving your coins for a decent radiator.

 

GTOGuy -


Thanks for the advise. I will probably use the high density foam as you recommend. It seems like it would be easy to trim so that it still looks good. I will definitely get the Dewitt's eventually, but I'm down to four weeks before I give the car back, so it will unfortunately have to wait. The seven blade fan sounds like an option too, as long as I can find a steel one; I'm trying to keep it as original looking as possible.


Thanks again!


Jim

 

Your fan is working counterproductive right now. You need to get a spacer on the fan to move it closer inside the shroud. That would help. Careful with the foam. Make sure it does not fly off... I had the top piece fly out and melted on the exhaust manifold.


https://www.summitracing.com/parts/sum-g4953

 

Thanks JimH,


I will pick up that spacer today. I will make sure that foam is glued well also - great tip.


Thanks,


Jim

 

I don't understand why your fan is not located correctly. It appears from your picture everything is stock. The only other thing I would suggest is check your timing.

 

Something is amiss with the shroud-to-fan configuration as noted.
The first pic is my fan with a spacer in place of the fan clutch and pipe foam along the top and down each side works splendidly!

There should also be a rubber seal along the front of the lower edge at the radiator and a triangular rubber seal at each corner in the front...you can make them out of old floor mats, rubber tool box liner or buy repros.

 

I'll add, never add a spacer to a fan clutch. If you can't get the right dimension fan clutch, install a solid spacer and eliminate the clutch, as pictured by Frank. A spacer on a fan clutch puts too much load on the water pump bearing, a load it was not designed for. Throwing a fan thru the hood on one of these cars is not fun or inexpensive.

 

His clutch fan shaft is too short and needs to be longer. The space is very small and will not add stress. The spacer will work fine or replace the clutch fan with longer shaft. The spacer I am talking about is roughly 1/2 to 3/4 inch. It will not cause any load. Your fan will not come flying off.

 

Thanks Moxie,

I read earlier that the timing could cause over-heating problems. I do plan on checking that.

Thanks again,

Jim

 

Frankie, GTO, Jim,

Thanks very much for the input. Frankie, that insulation looks great - I will pick some up and give it a shot. I've should be able to get the spacer installed tomorrow. I just need to decide on fan clutch or no fan clutch. Decisions, decisions......

 

Clutch fan will work fine but that's your decision. Running lean or running a hotter plug with an incorrect gap will cause it to run hot too.

 

Although not stock. What I did on the gaps was use thin foam insulation covered in aluminum foil, then fiberglass cloth with resin that covered that. Then painted to resemble carbon fiber. On both sides of the top of the radiator I cut and shaped cardboard to fit then covered with resin and painted to look like carbon fiber.


In front of the radiator I have a rubber cover around the edges of the radiator keeping any air from going around the radiator. i also use fiberglass screening to keep the bugs and cotton wood out.

 

Excellent recs so far. But for those who are searching this topic in the forum in the future, I want to mention a key point that has been mentioned in similar posts in the past that has not yet been mentioned:

How do we know you are running hot?

The odds are you have already done this, and thus need to work with the excellent suggestions so far, But if not, here is the next key step:

Buy an infrared temperature scanner.

The stock temperature gauges and senders on these cars are notoriously inaccurate. How bad? There are even inline resistors that are sold to correct the situation:

http://www.parts123.com/corvettecent...50e&ukey=30980

A personal example: I ran a 7300 FI unit on my 57 for 25 years. Never ran hot. Then I decided to convert to correct dual quad set up for my car. Ran 220 right out of the box. Being a racer, I immediately checked all the stuff that could have changed with what I did- timing, proper air/fuel ratio, etc- no difference. Then I researched the forum, and found all the complaints about the inaccurate senders and gauges. So I got my trusty infrared temp scanner out of my toolbox that I use for tire temps at the track. Radiator hose near thermostat? 178 degrees. Thermostat housing? 181 degrees? Radiator? 175 degrees. My car wasn't running hot- the sender/gauge combo just sucked. So I installed the resistor above, and now I trust what I see on the gauge.

If this doesn't help, my apologies, and I defer to the experts. But hopefully it will help some newbie from pulling their hair out

Good luck!
Marc in Indy

 

I agree with the others, you have to get that fan forward and partially into the shroud. The other thing I wanted to mention is we make a good aluminum radiator for those on a "budget".

This is NOT the correct reproduction but rather a replacement radiator from our Direct Fit line. This is a double row core with standard end tanks. We even use the same cast necks as the restoration radiator so it looks real nice in there with the Black Ice option.




Link to page

 

Thanks all for the outstanding recommendations. I admit that I have not checked the temp with an ir thermometer, I will do that today. C1 generation - your solution is beyond awesome and looks fantastic, but may require more time (and skill) than I have. I will most likely have to forego the fiberglass and carbon fiber painting for now, but I do plan on adding the foam and putting in a 1 inch spacer.

That DeWitt's radiator looks outstanding, I'm definitely going to check it out.

Thanks again!

 

I forget about the flaky temp sending units - you really should check that out, many have been found to be 20* or more too high. Lots of info here on the issue...

 

Thanks for the compliment. You might say that some person already liked the pieces I made for the sides of the radiator enough to steal one of them. Now I have them glued in place.
As far as temperature variations, mine reads about 40 lower than it should. But that is on a newer GM crate motor.

 

Lots of great advise here already.. I'll just add that I found a leaky cap caused mine to run hot. Perhaps because the system could not pressurize... squeeze the top hose when the car is hot and it should be firm.

 

Also don't forget the gaps at the sides.. I copied Frankie and pushed some foam pipe insulation into those gaps. Seals very well and doesn't even show.