Hi Frank! I got a "retirement" job as a supervisor in a machine shop - and its been a bit more than I really wanted!!!!!!!!!!! Not too much time in my own garage.
So now that I've nearly reached the big "70", I figure its about time to get with the program and finish a few projects I set on the shelf.

 
 Steve Metzger       Tucson, Arizona

Steve,
Was beginning to wonder if you were still around, and sane !



Frank/Rebop

Bristol, In ( by Elkhart) 

Bypass restriction works fine on my outfit - for desert use here in the southwest. A lot of water flows through the 5/8 line right past the radiator and recycles. Too much when the water is hot and engine speed is low. I did a test by replacing the short bypass hose with an old chunk of 5/8 garden hose - plugged the water pump port. Ran the engine at idle speed - thermostat closed - observed the amount of bypass water produced as it squirted into the open radiator cap from the open 5/8 line. This flow is just from water pressure - so actually, more water would be transferred if there was also a suction applied such as at the water pump port. Made me a believer in what I had heard about the lost cooling capacity when the thermostat is open - seeing is believing.

So my outfit now has a thermostat with drilled bypass holes - and a 3/16 orifice installed in the short bypass hose. Water flows right away on start-up - but recycle is way reduced from the stock set-up. Why recycle water when the engine is hot? 

The best change I made was to fit the engine with a smaller water pump pulley - and therefor increase the pumping capacity at idle. If you open the radiator cap of your outfit with the engine warmed up, at idle - thermostat open - you can see whether or not water is moving in the upper radiator tank. I had a Merc with a 289 and water absolutely gushed at hot idle - the 312 barely sloshed when I started trying to trouble shoot the cooling system. My bird still has the original 2/3 size radiator (completely rebuilt and rodded out) - and when I started, the original 3 blade fan. It now has a fan clutch and an aluminum 7 blade fan sized to fit the factory shroud.



 
 Steve Metzger       Tucson, Arizona

MAIN REASON FOR BYPASS IS 1 STOP WATER PUMP CAVITATION 2 KEEP WATER FLOWING IN ENGINE WITH STAT CLOSED

For TBirds, CASCO has a water pump with longer vanes to help coolant flow.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

If it uses the same Diameter Stat as Y Block there is a very reasonably Priced High Flo Stat from napa. The opening is bigger than regular stats.

As an FYI, the FE and Y-block use the same thermostat and I do have the numbers for the high flow version. Mark, thanks for the tip on using vinegar to prep the alum. Tank is way too shiny for my work truck.



AKA   Bob-93021

How is any goal post being moved?
Trying to have a simple conversation. Guess not ...

____________________________

You can't keep moving the goal post.

Sure, repositioning the pulley will change the load on the bearings but here again, it's a mod that's been done many times, probably more than the restriction and water pumps aren't failing.


Lawrenceville, GA

It is a bird but if I'm remembering right, a part of the changes was removing the water pump spacer, then spacing the pulley to keep the belt in line, which then makes it like every other Y and potentially applicable to all, which is why some others have benefited from it.

Correct. But the problem is (IMO) that removing the spacer and spacing the fan/pulley out an additional 1" (with possible additional weight of an extra blade fan) would put an undue stress on the WP bearing. FORD didn't think the problem out very well when moving the BIRD engine back so far for fitment.

There is the re-designed spacer and FLOW-KOOL offers an improved WP impeller which will enable one to retain OEM appearance and correct numbers and proper cooling.

You have to remember I am extremely CDO (correct alphabetical order of OCD)

____________________________

The 54 239 also had a smaller water pump.     
  Dennis in Lititz PA

Another good point. Also smaller coolant passages in the heads/intake.

____________________________