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I made a hugh mistake by installing air conditioning on my 64' corvette. Since then I have had overheating problems. At this time, I have replaced the correct radiator (72 year) with a new cold case radiator. 1 1/4 inch tubes, dual row, crossflow, all alum heavy duty. Long island Schwitzer clutch, 7 blade correct fan. Still runs extremely hot. with when AC turned on unless on highway. My newclutch fan spins close to 15 or 20 times after turning off engine which I believe shows its not locking? Does anyone think a Dewitt high HP will cure my problem. Also, just to be sure I didn't take a stupid pill, my fan rivets and flange on the blade face the the engine and the "H" faces the radiator. NEED HELP Really getting tired of this! Thanks
Took a drive today and the radiator went to 240 after a couple of traffic lights with AC on.
By the way, I confirmed gauge readings with a hand held gun I have
Well - for one thing your fan clutch is shot; per the top rebuilder of fan clutches:
I run a 63 with Vintage Air that I added withOUT electric fans and the car never hits 190*...completely stock engine with an original "608" water pump
I don't know what a "cold case" radiator is, I have a DeWitts but had the original radiator for a while and neither was a problem...
I run a 2747 Hayden heavy duty fan clutch and a BB 7-blade fan (on the left in the picture) and also have the '67 A/C rubber flap along the top of the radiator which helps direct air flow...it'll fit on any midyear with some trimming.
Last edited by Frankie the Fink; Apr 18, 2020 at 06:52 PM.
Besides what has already been mentioned (all of which I totally agree with) you could also eliminate the clutch on your fan completely (at least while you send it off to be rebuilt/repaired) and instead install a "fan clutch eliminator kit" available from LIC and others for about $65.00. I ran one before I installed my new engine and it worked great. Not exactly NCRS but they do work. It is any easy switch and at least you could confirm that your fan clutch is toast.
If you want to get a touch more radical you could also move your front license plate bracket to the driver's side by substituting the one used by C2 BB's with Air and Automatic. It helps to eliminate the blockage of air straight into the front center of the radiator by the standard plate position. Of course if you live in a State that does not require a front plate then disregard. Here is the link to the clutch eliminator . . .
The clutch is a new one from K&B. I haven't called them yet because its late Saturday, tomorrow Sunday. Probably have to start there. Also I have the flap on the top of the radiator. Its pretty well sealed.. To Frankie........I have an Old Air Ac with the OEM A6 compressor
As others have said, your clutch is not functioning. If it spins for 20 revolutions, it almost like having no fan at all. Do the easy stuff first. Lastly, you are going to love the AC when you get this straightened out. Jerry
Tampa Jerry........I thought I did as I kept adding new parts. The clutch fan should have worked as thought that K&b good reproduction of the Schweitzer clutch. I didn't get it installed until today and noticed the spinning as my engine was at 240 degrees after I turned off the car. I knew that wasn't right.
Your fan clutch doesn't sound good, but I doubt it would affect the cooling much when driving down the highway. Does it seem to cool any when you're moving at a good pace? Have you verified that the thermostat is opening. At that temp, it sounds like you're not getting coolant flow through the radiator at all.
Radiator needs bottom seal as well. Also a lower fan shroud extension. Both were furnished with factory AC cars.
Check your radiator BTU/HR rating vs the DEWitts. DeWitt number is published on their website. Call your current radiator supplier for his rating. I would also check using IR gun your radiator in and out coolant temperatures at idle and 2000 RPM. Let stabilize for a few minutes for each reading.
Fan blade must be positioned about 1/2 in and 1/2 out of radiator shroud for best cooling.
Assume coolant is 50/50 mix and clean or new. Make sure of this.
Vac advance must be working correctly. Check yours.
Get a better fan clutch that works. Frankie's Hayden clutch and 7 blade fan is a great setup.
Thermostat must be 180F for best cooling and oil life.
I need to check the BTU rating and the vac advance. All the other points I have correct. The clutch is clearly not working correctly as I see this. Also checking the Btu/Hr rating could same me a lot of work. The radiator seemed to cover all the aspects of a good radiator for this car. Extra thick alum construction, 2 rows 1 1/4 with crossflrow Tig welds, no epoxy , made in USA etc. I hope I don't have to remove and replace. You had a couple of good points I need to check out. Thanks
Finding a good HD clutch is impossible except for the Hayden. However, the standard clutch was correct by hayden with 3" holes, but the AC called for HD clutch.
Use Frankie's combination of clutch and blade. You NEED maximum air flow at low RPM or idle. So find a way to get it. Another fan blade won't be the end of the world regarding $$.
Could your combination of extra thick radiator and condenser together make it very (very) difficult to get the air flow thru the radiator?? Something to think about.
You need to do the radiator in and out temperature testing to get a handle on performance. JohnZ's article on cooling provided reference delta T temperatures. Tom De Witt can also provide this information if you ask him.
I may have confused you all. The alum is thicker, not the radiator. Also, I was trying to keep my original 7" blade if possible. I have tried to keep car as original as possible, but some time it just doesn't make $ sense. Thanks for all your help. Most of you have been helping me for the 4 yrs I've been rebuilding this car. Thanks to all of you for your shared knowledge. It has really helped.
Overheating
