antifreeze is also useful in stoping erosion cast iron  exposed to moving water,and essential if you are useing aluminum parts,such as radiators.Caterpillar learned years ago that linner erosion and alum. water components eaten up was NOT electrolysis ,bur water making sharp bender,and colideing with flexing linners during combustion. good quality antifreeze eliminated thes issues. if you question this go to a cat truck engine dealer and you will be surprised.
ps most of us are aware of anty freeze increasing the boil point. my concerns ar what the guys in hot climates use to control erosion.

Thanks everyone for all the great info on pulley sizes, thermostats and other over-heating remedies.  When I started this thread I had no idea so much helpful information would be offered up.  Hope everyone has a great Memorial Day weekend.  Ron...

The results are unclear as to whether adding the stainless steel plate that sandwiches between the water pump and 1” spacer helps or not.  My experience has been it does not not provide any additional cooling.  Here’s a link to a past discussion regarding that plate.  Doing a search will bring up some more threads regarding that plate.
http://forums.y-blocksforever.com/FindPost82934.aspx

Lorena, Texas (South of Waco)

I like the idea of using the late 60's 302 water pump pulley for increased pump speed. Flatrod made note of different belt widths for 56. I had forgot about different belt widths. I thought Ford used a wider belt up to 56 and changed to a narrower belt starting in 1957 for most car engines. I will take a look at my 56 Fairlane and 68 Ranchero tomorrow and take some measurements.
Question.  For those of you that have made the switch to the 302 pulley did you also change gen/alt pulley and crank?  Or is the change in width insignificant?

272meteor, You raise a question about people in non-freezing climates not using antifreeze. Yes, many uninformed people back in the 50's or so did not have to worry about freezing and would use just water!!!  I am from the rust belt area so I know about need for antifreeze. Later transplanted to no freeze area. I must admit that I did not bother with antifreeze in my cars in SoCal unless they had aluminum parts exposed to water.  Yea, hard to believe. I now know better


AKA   Bob-93021

(1) The use of anti-freeze is necessary if you wish to suppress the boiling point of the coolant - whether the climate is hot or cold either one........
 
Since most of our efforts are directed toward avoiding a boil over, a 50/50 mix is the usual formula for most of us. Using the chemistry data above - you could further suppress boiling by using a "richer" 70/30 mix. 
Step next would be to optimize the pressure cap - if the radiator is in good repair and of modern construction methods - then choose one  that suits your equipment (or the OEM spec).

 
 Steve Metzger       Tucson, Arizona

I have some questions  regarding y block users in extreme hot conditions.
1 does every  one use anty frees,or other any corrosion additive.
2 how maney restrict the by pass.
the reason for this info is i recently took a core from a user in la aria, 292 from57 ford car,low milage.  the front cover was eaton threw from erosion the damage to front cover far more evident on driver side wher water enters block. it as right threw the casting at that point (no coolest additive or anty freez). have yet to clean block to check for damage due to cavitation.
 with no bypass you will have cavitation,i run 2 temp gauges there is always a spread of temp of apron 10dgrs.higher at the stat end. in our cooler climate we do not have over heat issues as long as the cooling system is maintained.good pressure cap good therm, any frees winter and summer

Greenbird56

    Thank you for the info. My 56 bird has wider belts, so the 302 pulley will not work for me. It looks like I will be needing a new pump anyway, so I will go with Casco water pump. I already have the right thermostat.  

I've got an idea that it is NAPA p/n THM 170 - dislexia has set in in my old age ...... that part number is for a 180º t-stat (which would be a good temp choice for most applications). The NAPA site says the OD is 2-1/8. The main idea we need to pursue is to end up with a poppet opening of 1-1/2 inches (not 1 inch like a chebbie). When I looked the part up, it was only listed as being a $6.00 purchase - and that is what I remembered about the part we found before - very inexpensive.

My new office isn't right next door to NAPA (as it was before) - so maybe someone can check it out......?

 
 Steve Metzger       Tucson, Arizona

I don't know the Napa part number.


Lawrenceville, GA

Charlie - Do you have the NAPA number for their 170º t-stat? It was the other poppet style (not like Robertshaw), but had a full size opening and 2" overall dia. I should have retained the number when I found it.........! You just don't want to end up with the itty bitty size of opening fitted into a large blank disc seen on the left below.


 
 Steve Metzger       Tucson, Arizona