The cfm rating of the fan is not a issue with a highway speed running hot issue like the op has posted about.
At this point I would try combustion gas tester to rule out cracks or leaking head gasket. About $30 for a kit at most auto-part stores. Most important to do the test a couple of times, and make sure you do not get any coolant into the tester as it will affect the test solution. Since it is highway speed, I would check timing at that RPM steady, and be sure advance is working correctly. I realize you stated you reset the timing, but did you check it at the same RPM it is getting hot? And, if so, what is the timing at that RPM?
Really need to know the ignition timing at your typical cruise RPM. This is very easy to check with a dial back, or even standard timing light. Just because the vacuum advance is connected doesn't mean it is working. The mechanical advance could be sticking as well. You need to verify the timing. Hook up the light, rev the engine to 2000 RPM, or whatever it's revving at 60 MPH, and see where the timing is. It should be 40+*. If the VA is not working, it will be less. Retarded timing will result in more heat going into the cooling system instead of pushing the piston down.
If this were my car and problem I'd do all that you have done and my next step would be to remove the A/C condenser and do more driving to see if the issue improves.
By any chance is this a street rod with a small grille opening? Ensuring the air entering the grille is going thru the radiator by blocking off openings around the rad may help, if large openings exist. I drill a small hole, maybe 1/8" in my thermostat to act as an air bleed to ensure the system is full of coolant at fill time, not air pockets. You can increase/decrease to water pump speed by changing the size of the pulley. A damaged timing cover may have too much clearance at the pump impeller. I believe it's caused by cavitation. This may reduce pumping efficiency. Measuring radiator inlet/outlet temp should give you an idea of whether: 1) radiator is big enough. 2) water flow is sufficient.
I will remove the condensor if it is still a issue. This is the stock engine in my 1960 Buick, I did drill the hole on the last thermastat I installed. They only have one size pulley for this engine. Thanks for all the tips.
It was worth asking. One of my neighbors had an overheating problem in his Toyota for precisely that reason. The main purpose of antifreeze is freeze protection. Antifreeze does not conduct heat as well as plain distilled water. The only other concern is anti corrosives. If you live in a climate where freeze protection is not a concern, or for the summer, the best heat transfer can be attained with distilled water and a product like Red line Water Wetter, https://www.redlineoil.com/waterwetter Bottom line is the less antifreeze you run, the better for heat transfer.
Ok another update on car getting hot. So put the aluminum radiator back in. Cut holes in the shroud. Took it for a drive at highway speeds with the AC on. Top pic is what it got to driving at 60 mph. Middle is I lifted the front of the car up with the air ride. Bottom is slow speed. So I need to add flapper doors to the cut out. Before the holes it ran cool at low speeds and got up to 235 at 60mph.
OK, after reviewing this entire thread, I saw several unanswered questions. First, you said you have a 4 core aluminum radiator. If so, you likely wasted your money. A 4 core brass/copper would likely cool better. To avoid repeating what I have posted countless times, here is my sticky on Aluminum Radiators in the FAQ Forum, https://www.v8buick.com/index.php?threads/aluminum-radiators.369954/ I don't see an answer to my ignition timing questions. It's really important to see if you have adequate mechanical and vacuum advance to get your timing to at least 40* at typical cruise RPM, as well as at slow speed. If the engine timing is relatively retarded, it will heat up from that alone. I don't see the need for electric fans on our cars. The stock clutch fan and shroud keeps my engine within 5* of the thermostat rating. Your fan set up looks restrictive to me.
I will read your post on the aluminum radiator. When I first put my AC in I had the original radiator with e 6 blade mechanical fan no clutch and no shroud, they didnt come with them, I could run at highway speeds and would only get to 205-210, but got very hot at idle and running low speed. So installed the aluminum radiator and with electric fan and shroud and could idle and run at low speeds and never get over 190. So this last run added the hole which let the air flow at high way speeds and dropped the temp down, but runs hot at idle and low. This is where i need to add the rubber flaps so it acts like it did before adding the holes. I did talk to the radiator people and the 4 core may be to thick and said a 2 core with 1" tubes would probably cool better. Also I am still going to look at the timing but have not yet. Thanks
I have a question, if a 4 row Aluminum is too thick then what parameters need to met to have a need for one ? I know that with each added row that it does not increase the amount of heat transfer as much as the does row before it , but gez I mean come on!
I explained this in my FAQ thread on aluminum radiators. First, aluminum DOES NOT conduct heat better than Brass/Copper, BUT, aluminum is a stiffer metal. Aluminum can support tube sizes up to 1 1/2". Brass/Copper tube size maxxes out at 5/8". Any bigger and the tubes would balloon because they are softer metal. Bigger tubes equal more tube to fin contact. That means better cooling with less rows. 2 rows of 1 1/4" tubes will out cool a 7 row Brass/Copper radiator. That 4 core aluminum radiator likely has small tubes. That means it is LESS efficient than an equivalent radiator made out of Brass/Copper, because Brass/Copper conducts heat better. I've been warning members here for years about this. Most manufacturers know this, but despite that, they will still market 3 and 4 core aluminum radiators. Buyer Beware. You want tube size of 1" minimum, 1 1/4" is better, and no more than 2 rows. Racers use a single row aluminum radiator with the bigger tubes. It's a 90's Park Avenue radiator.
In general: - High temp at highway speed = insufficient cooling capacity (or retarded timing) - High temp at slow speed = insufficient airflow. In summary: **You had decent results with your old rad at highway speeds but need additional airflow at slow speed. **The alum rad with shroud restricts airflow at highway speed, but worked well at slow speed. Since you've seen a temperature decrease at highway speed with windows cut in the shroud (good idea BTW), you've proven the shroud is restricting the airflow. **I'd like to see a test with a mechanical fan and no shroud (alum rad). If it's still running hot, the alum rad isn't up to snuff. (I would expect it to run hot at slow speeds with mech fan/no shroud). You did have decent results with your old rad. On my blue 66, I have a clutch unit that came off a mid 80's v6 Regal, fits the Nailhead fine. I had to find a smaller 18"? fan from a Caddy, the Regal fan was too large of an OD. Maybe you can find a V6 clutch fan to try out. Maybe a dual elec fan/no shroud setup would work better, we can determine this later. **There were differences in early vs late water pumps, I don't know the early stuff, or if that could be a problem. **Proper timing needs to be verified, although you were cool at hw speed with your old rad. The solution, IMO, is a different fan or shroud setup. We still need to determine which radiator works best.
A tight fitting shroud around an electric fan of insufficient CFM will limit the CFM even at highway speeds. So one more time: what is the CFM rating of the fan??
