Pulley Diameters

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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
 
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

Glad that changing over to a smaller water pump pulley has helped with the cooling! With a 109* ambient temp running at 210* is doing pretty good!

But, about that alternator. If you didn't change the size of the crank pulley or the alternator pulley, you didn't change the alternator speed. It doesn't matter what the size of the other driven pulleys are or how many other driven pulleys are in the system, the speed is determined by the driving pulley and the pulley being driven. So, all that matters for the alternator speed is the size of the crank pulley and the size of the alternator pulley.
 
Glad that changing over to a smaller water pump pulley has helped with the cooling! With a 109* ambient temp running at 210* is doing pretty good!

I agree & am pretty stoked. I doubt I'll drive it much in weather like this, but I figured why not test it in the most extreme conditions...

But, about that alternator. If you didn't change the size of the crank pulley or the alternator pulley, you didn't change the alternator speed. It doesn't matter what the size of the other driven pulleys are or how many other driven pulleys are in the system, the speed is determined by the driving pulley and the pulley being driven. So, all that matters for the alternator speed is the size of the crank pulley and the size of the alternator pulley.

I take your word for it, but for some reason it's better. Maybe magic LOL :)
 
magic meme.gif
 
Glad that changing over to a smaller water pump pulley has helped with the cooling! With a 109* ambient temp running at 210* is doing pretty good!

But, about that alternator. If you didn't change the size of the crank pulley or the alternator pulley, you didn't change the alternator speed. It doesn't matter what the size of the other driven pulleys are or how many other driven pulleys are in the system, the speed is determined by the driving pulley and the pulley being driven. So, all that matters for the alternator speed is the size of the crank pulley and the size of the alternator pulley.
--------this !^^^^^^^^^^^^^^^^^^^^^^
 
...I doubt I'll drive it much in weather like this, but I figured why not test it in the most extreme conditions...

Exactly.
But, if you want to, you can drive it in the hottest weather the metro area can dish out!:thumbsup:

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Exactly.
But, if you want to, you can drive it in the hottest weather the metro area can dish out!:thumbsup:

I'm encouraged, but not totally convinced of that yet. When we have a day in the future that is 100* or less, I plan to take it for an hour or more test on the freeway. Sustained speeds of 65+

I'll update when that happens. Thanks :)
 
before sustained speed testing please put on your shower caps :D
 
You mentioned that you have a clutch fan. Are you sure that it is working PROPERLY ???
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+I will throw in here. I drove my 505" fish yesterday , 96* w/ humidity. The hottest I have driven the car so far. Running a 17", 7 blade alum. fan that has a steel center( factory). A new flow cooler water pump, w/ a new jaguar 2765 clutch.. It ran at 195 for a while, then 198, the 202, held for a while, then in town went to 210 and held steady, got out on the 4 lane coming home started showing of a little, "really wanting to see how hot it would get w/ the new set up." It went to 216 and stayed there till I got home, and went to 220 after shut down. Not too worried about it now, but I think the shroud is too thick, as the clutch puts the fan almost inside the shroud, w/ only about 1/2" sticking out the engine side. I think the 10,000 rpm flex fan , belt driven would fit the shroud better and make it run a cooler (I think) , but I `ve been switching stuff around , experimenting so much, I`m tired of fooling w/ the dam pump bolts. The jaguar clutch to pump bolts were a *****, ended up using studs, getting all the nuts w/ lockwashers started before tightening any down, even had to file a spot on the clutch hub in one spot for a little more clearance to start the nuts! Anyone kick in here w/ thoughts ???
 
+I will throw in here. I drove my 505" fish yesterday , 96* w/ humidity. The hottest I have driven the car so far. Running a 17", 7 blade alum. fan that has a steel center( factory). A new flow cooler water pump, w/ a new jaguar 2765 clutch.. It ran at 195 for a while, then 198, the 202, held for a while, then in town went to 210 and held steady, got out on the 4 lane coming home started showing of a little, "really wanting to see how hot it would get w/ the new set up." It went to 216 and stayed there till I got home, and went to 220 after shut down. Not too worried about it now, but I think the shroud is too thick, as the clutch puts the fan almost inside the shroud, w/ only about 1/2" sticking out the engine side. I think the 10,000 rpm flex fan , belt driven would fit the shroud better and make it run a cooler (I think) , but I `ve been switching stuff around , experimenting so much, I`m tired of fooling w/ the dam pump bolts. The jaguar clutch to pump bolts were a *****, ended up using studs, getting all the nuts w/ lockwashers started before tightening any down, even had to file a spot on the clutch hub in one spot for a little more clearance to start the nuts! Anyone kick in here w/ thoughts ???

I might try a smaller diameter fan pulley if I can find one that will work w/ my steel crank pulley.
 
If your temperature was still climbing while at speed out on a 4 lane highway the fan isn’t the issue. At highway speeds the clutch shouldn’t even be spinning the fan, so the shroud shouldn’t be the issue. The fan should be about 1” inside the shroud, but being a little off will only be a small efficiency change, not a drastic problem.

So if your temps are climbing at speed usually the issue is that the radiator is on the small side (or plugged up), or you may have a circulation problem. The smaller water pump pulley would speed up the fan (when it’s spinning), but it would also spin the pump faster too. Which may help with the sustained speed temps.
 
and don't forget the AC cars have the Fan pulley over drive like you state but they also have the 6 blade pumps vs the 8 blade pump since they are spinning faster I am assuming you get cavitation with more blades at the higher speed it runs.
 
If your temperature was still climbing while at speed out on a 4 lane highway the fan isn’t the issue. At highway speeds the clutch shouldn’t even be spinning the fan, so the shroud shouldn’t be the issue. The fan should be about 1” inside the shroud, but being a little off will only be a small efficiency change, not a drastic problem.

So if your temps are climbing at speed usually the issue is that the radiator is on the small side (or plugged up), or you may have a circulation problem. The smaller water pump pulley would speed up the fan (when it’s spinning), but it would also spin the pump faster too. Which may help with the sustained speed temps.

Yeah, this is *** backwards from the way it performed heat wise before. Never had it climb on the hi way, always cooled off before putting the clutch type fan on. I did a little airflow mod. behind the front grill area yesterday. I think the 17 1/4'' flex fan was the best as far as fans go, "so far".
-Not worried about it much right now, it`s close to where I want it. The heat has been fairly bad here lately. Will be testing and playing w/ it on the hotter days coming up.
THANKS FOR ALL THE COMMENTS AND SUGGESTIONS. ---
 
Don’t really mean to disagree with others experiences but my extremely overheating stock 340 barely gets into normal operating temperature. All I did was to replace the thermostat and fan clutch.
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Don’t really mean to disagree with others experiences but my extremely overheating stock 340 barely gets into normal operating temperature. All I did was to replace the thermostat and fan clutch.
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So you think everyone that has overheating problems has a bad thermostat and fan clutch like you did?

Seems overly simplistic. Several of the people in this thread sorting out heat issues have already replaced, or confirmed their thermostats and fan clutch are working. There’s a bunch of different parts involved, not everyone will have the same problem.

Not to mention, you said stock 340. Many of the folks in this thread have stroker engines that are bigger than 340 ci and make a lot more horsepower than a stock engine. More horsepower = more heat.
 
I said I didn’t disagree with others. All I related was my experience. My problem was simplistic. Usually the best approach is to start with the simplest, easiest and cheapest possible solution to a problem until those possibilities are eliminated.
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I said I didn’t disagree with others. All I related was my experience. My problem was simplistic. Usually the best approach is to start with the simplest, easiest and cheapest possible solution to a problem until those possibilities are eliminated.
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Right. And when those have already been ruled out, you move on.
 
I know on a big block with A/C the water pump is pretty small. I imangine the same would apply for a small block.
 
I know on a big block with A/C the water pump is pretty small. I imangine the same would apply for a small block.

I already posted the water pump and pulley size information on the first page of this thread. AC cars, both small and big block, used standard 6 blade pumps while non-AC cars used 8 blade high volume pumps.

But the AC cars had smaller pulleys, which overdrive the water pump and fan. The non-AC ratio is .95:1, the AC ratios were 1.3:1 and 1.4:1. So the AC pumps were overdriven 35% to 45%, and the HV pumps were only a 20-30% increase in flow. Meaning the standard pumps on the AC cars were still moving more volume than the HV pumps on non-AC cars.
 
Would overdiving high volume water pump cause cavitation or any other issues?

I doubt that it would be a major problem. Obviously it's possible, but unless the engine is going to be consistently operated at high rpm I don't think I'd spend too much time worrying about it. I run a HV water pump on my 340 and the March pulleys on it have a ratio of ~1.04:1, so, that's almost 10% higher than the factory ratio for an HV pump. I haven't had any issues with cooling on my car at all, and it's a 9.8:1, .060" over, 340 with iron heads and 3.55 gears that I frequently run up and down the freeway at a constant 3,500 rpm. Granted 10% overdriven isn't 35% like it would be with the factory small block pulleys.

Looking at the factory numbers and ratio's, and working off of the advertised gains for a HV pump (20-30%) it looks to me like what they were doing was keeping the volume of water moved by the pump close to the same for the two systems. Which probably means they had done the cooling calculations based on that volume of water being moved, and just held that as a constant. The AC cars suffer from the radiator air flow being obstructed by the condenser being mounted out front, so they had larger radiators and overdriven fans to increase surface area and air flow to compensate.

Now you could argue that they optimized the volume of water being moved for the whole system, which is why they wanted to keep it close to the same. So, running the HV pump with an overdriven pulley might not be as efficient. But of course that assumes you have a factory radiator that has the same resistance to flow as what was originally calculated. Aftermarket radiators with different tube sizes wouldn't be the same either.

There's a ton of stuff to consider. I wouldn't worry about it, but if I was having problems with cooling it is something to consider.
 
I doubt that it would be a major problem. Obviously it's possible, but unless the engine is going to be consistently operated at high rpm I don't think I'd spend too much time worrying about it. I run a HV water pump on my 340 and the March pulleys on it have a ratio of ~1.04:1, so, that's almost 10% higher than the factory ratio for an HV pump. I haven't had any issues with cooling on my car at all, and it's a 9.8:1, .060" over, 340 with iron heads and 3.55 gears that I frequently run up and down the freeway at a constant 3,500 rpm. Granted 10% overdriven isn't 35% like it would be with the factory small block pulleys.

Looking at the factory numbers and ratio's, and working off of the advertised gains for a HV pump (20-30%) it looks to me like what they were doing was keeping the volume of water moved by the pump close to the same for the two systems. Which probably means they had done the cooling calculations based on that volume of water being moved, and just held that as a constant. The AC cars suffer from the radiator air flow being obstructed by the condenser being mounted out front, so they had larger radiators and overdriven fans to increase surface area and air flow to compensate.

Now you could argue that they optimized the volume of water being moved for the whole system, which is why they wanted to keep it close to the same. So, running the HV pump with an overdriven pulley might not be as efficient. But of course that assumes you have a factory radiator that has the same resistance to flow as what was originally calculated. Aftermarket radiators with different tube sizes wouldn't be the same either.

There's a ton of stuff to consider. I wouldn't worry about it, but if I was having problems with cooling it is something to consider.

I`m wondering if the big diameter of the new fan clutch , (7") , w/ the 7 blade fan , along w/ the trans cooler , and 15" pusher fan , altogether are too much air flow restriction .
The thing has always cooled down on the hi way before installing the new jaguar clutch, and 7 blade fan..
After another hot day test, I`m thinking the best set up for "my" combination will be the 6 blade 17 1/4" 10,000 RPM flexfan. More to come ----------------
Almost forgot , anyone know of a single belt / smaller (overdrive ) pulley that will line up w/ a standard deep single bet crank pulley ?
 
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