Pulley Diameters
Ok a few questions. I'm having heat/cooling issues.
Here is a pic of specs from my 67 manual.
I see the ratio is slightly different. My questions,
1. Isn't the ratio(fan:crank) meaning the fan pulley is bigger than crank pulley?
2. C, what size pulleys did you decide on?
3. Wouldn't a larger pulley speed it up, as opposed to the smaller pulley?
Thanks
Ok a few questions. I'm having heat/cooling issues.
Here is a pic of specs from my 67 manual.
I see the ratio is slightly different. My questions,
1. Isn't the ratio(fan:crank) meaning the fan pulley is bigger than crank pulley?
2. C, what size pulleys did you decide on?
3. Wouldn't a larger pulley speed it up, as opposed to the smaller pulley?
Thanks
Again with the coolant circulating too fast to dissipate heat argument? Seems like all kinds of people think this. And for no good reason, because that's not what's happening.
Air is moving past the radiator at speed, whether being pulled by the fan or pushed through by the speed of the car. The velocity of the water in the radiator would have to be spectacular for it not to shed heat because it's being exposed to a large volume of moving air as it flows through the radiator. The water isn't just flowing through the radiator in stationary air, the air is moving too and that makes a BIG difference.
The next thing is that if the water really is circulating faster, it’s also making more passes through the radiator. Even if the heat lost on a single pass was less, the water would make more passes in a given amount of time. So, the heat lost could still be higher overall, it's not a slam dunk that the water going faster is worse. And that's even if you assume it's going fast enough that it's losing less heat, which is a big fat assumption.
And then there's just the thermodynamics of water. The hotter water gets, the more it wants to shed heat, and the harder it is to get it to take on more. So, if anything, the argument for water circulating too fast should be on the engine side. In the engine the water is moving, but the heat source is not. The faster the water goes through the engine, the less energy it will pick up, and the hotter the water gets the worse that will be. Meanwhile, on the radiator side, the hotter water wants to shed that energy even more. And the cooling source, the air, is moving. So really, if the argument is that the water is circulating too fast, then the reason shouldn't be because the radiator won't be able to dissipate enough heat. Instead, it should be that the engine won't be able to transfer heat to the water fast enough. (Which is why I run a high volume pump and NOT a high volume thermostat)
Just look at what the factory did on the AC cars.
View attachment 1715190210
AC cars got larger fans, larger radiators, smaller water pump pulleys (higher rpms for the pump and fan), and standard water pumps. So then you say, "HA! the factory didn't use high volume pumps on AC cars! Must be the water velocity!"
Except the factory spun the standard water pump 35% to 45% faster than the non-AC cars with the high volume pumps. How much more water volume do the high volume pumps move? 20% to 30% based on the information I've seen. So, is a standard pump spinning 35 to 45% faster really pumping less water? I bet it's not.
The surface area and air flow are the two biggest drivers of the cooling capacity of the system. Which is why the factory used larger radiators, bigger fans, and then spun those bigger fans faster. Why the smaller pump? Probably as insurance against cavitation as the pump impeller was spun faster. Because at the higher pulley ratio the standard pump was likely already putting out more volume than the high volume pump was at the slower driven speed.
Sure, your pulley ratio is 1:1, which is 30% less than what the factory did for an AC car. Which means your fan speed is 30% less, and your pump speed is 30% less than what the factory used. So it's very possible you aren't moving enough air OR water, especially if you're using a standard water pump.
I would look for a smaller water pump pulley. Or a larger crank pulley. You could also use a high volume water pump, because if you're using a standard pump with that 1:1 ratio you're not even moving the same amount of water as a factory non-ac car (same-ish ratio, but a HV pump). Although the HV pump wouldn't improve your fan speed like going to the smaller pulley would.
Ok, 1st update after initial "test" drive
Took the car for a 10-12 mile drive to get fuel about 2pm today. It was 109* out & HOT !! In town driving & stop n' go traffic with the AC on the entire time. The car reached 210*, but didn't climb any higher :D So far, I'm encouraged with the improvement.
As an added bonus, my digital volt gauge used to drop into the 11s at a stoplight. With the addition of the smaller water pump pulley, the alternator spins faster & stays in the 14 volt range...WIN - WIN
