Exploding water pumps? Difference in early 273 water pumps vs later 1970s 318 pumps

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Slantsix64

Slantsix64

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So yep my water pump decided to blow out, wtf?

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What are the differences with the later pump I know it’s longer so I don’t need to run a big spacers, is there a difference in the bearings
 
The long spacer and out of balance fan blade metal fatigued the snout.

NO NEED of a spacer that long. My dart 273 2bbl runs fine all day long with the stock spacer and stock 7 blade fan, no shroud as it came from the factory.

As for early Cast iron or later Aluminum water pump. they are different in many ways.

  1. the inlet is on the wrong side
  2. the mounting bosses are not the same height for the alt etc.
  3. the overall length is longer so the fan belts will not line up correctly
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Dana67Dart said:
The long spacer and out of balance fan blade metal fatigued the snout.

NO NEED of a spacer that long. My dart 273 2bbl runs fine all day long with the stock spacer and stock 7 blade fan, no shroud as it came from the factory.

As for early Cast iron or later Aluminum water pump. they are different in many ways.

  1. the inlet is on the wrong side
  2. the mounting bosses are not the same height for the alt etc.
  3. the overall length is longer so the fan belts will not line up correctly
View attachment 1716081135
Click to expand...
One of the problems I have been having also is that my square back alternator keeps hitting the magnum head so I had to grind some of the back alternator or else it would line up the belt crooked
 
Dana67Dart said:
The long spacer and out of balance fan blade metal fatigued the snout.

NO NEED of a spacer that long. My dart 273 2bbl runs fine all day long with the stock spacer and stock 7 blade fan, no shroud as it came from the factory.

As for early Cast iron or later Aluminum water pump. they are different in many ways.

  1. the inlet is on the wrong side
  2. the mounting bosses are not the same height for the alt etc.
  3. the overall length is longer so the fan belts will not line up correctly
View attachment 1716081135
Click to expand...
so maybe the later water pump might actually help me with that because the later alternator would of came with that kind of style water pump?
 
and as said, the lower radiator hose is on the wrong side.
Get the correct 67 water pump,
Get the correct 67 fan spacer,
Don't tighten the belts too much.
There is no need for that long spacer.


Alan
 
My 67 oem setup. 2 1/2" spacer 7 blade fan and shroud. Waterpump is a cast iron repop. Had to machine pads/bosses on alt side. Machining is/was off.
Part of your problem I believe is the magnum heads maybe?

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Something that always makes me wonder.

If you need 1/4" for everything to line up correctly.

Make 1/4" spacers for behind the crank andwater pump pulleys and same with the alternator, ps and AC brakets.

Move everything 1/4" inch toward the radiator!

Also if there is interference between alt and head, can't you grind / machine off the offending area of the head?

Or perhaps longer or shortest belt to position the alternator in a slightly different position?
 
I wonder what stewpot of parts I lucked into when I just screwed my stuff together.......

But I see you are running a tiny fan pulley, looks to be extremely small. My guess is that the ratio is something like 8 to 5=60 effing percent overdrive!
that means your pump is spinning 60% faster than the crank. And that means by 5000 crank rpm, the pump would be doing over 8000. It wouldn't take much of an imbalance to shake it apart.
I can't imagine why you would run it like that.

Are you having over-heat issues? Those are usually easy to solve.
 
AJ/FormS said:
But I see you are running a tiny fan pulley, looks to be extremely small. My guess is that the ratio is something like 8 to 5=60 effing percent overdrive!
that means your pump is spinning 60%faster than the crank. And that means by 5000 crank rpm, the pump would be doing over 8000.
Click to expand...
It might be a 6 1/2 inch crank pulley but good catch on the water pump pulley size
 
AJ/FormS said:
I wonder what stewpot of parts I lucked into when I just screwed my stuff together.......

But I see you are running a tiny fan pulley, looks to be extremely small. My guess is that the ratio is something like 8 to 5=60 effing percent overdrive!
that means your pump is spinning 60% faster than the crank. And that means by 5000 crank rpm, the pump would be doing over 8000. It wouldn't take much of an imbalance to shake it apart.
I can't imagine why you would run it like that.

Are you having over-heat issues? Those are usually easy to solve.
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yes it’s the smaller diameter pulley, original to my car which came with factory 1967 AC, I might swap it out for the larger one think I have one in my shed I’ve had two bearings go out in my water pumps that also might be a reason why the engine isn’t stock and it revs up to 5200 rpms before I shift, this all happened when I was doing a burn out so ya this is good to know
 
Cuda Al said:
When the AC was removed the wrong mix of parts was used.


Alan
Click to expand...
Not that I know of pretty much everything is the same I just swapped the crank pulley to one with no extra groove for A/C which the water pump belt lined up correctly, the alignment issues with the alternator was years after I swapped to magnum heads
 
AJ/FormS said:
Well it looked bigger than the balancer which are usually 7 so I just guessed, as I stated
Click to expand...
We are in agreement. I did not look close enough at the crank pulley it does look like 8" and the wp pulley looks tiny.

My money is on your estimates now that I looked at my 6.5 and 6 pulleys.

Imagine the alternator shaft RPM!

I was being optomistic, my 67 crank pulley is in the 6" range and my wp is in the 6.5" range - slightly underdriven per the factory for a non AC car.

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Do you have the alt spacer in place?

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Last edited:
The correct 67 non-AC water pump pulley is 6-1/2" diameter and 2-3/4" tall, the fan spacer is 2-3/8"
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Alan
 
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