V-belt to pulley contact

I recently installed an aftermarket alternator bracket on my 401ci Buick Nailhead.  The new set-up was done to allow me to move the alternator up and back from stock location.  This in turn with other modifications, allowed me to install a mechanical fan with deeply pitched blades in an attempt to pull more air through the radiator.
After these mods the first road trip was a gut-wrencher.  The engine ran at 225 on the highway for the majority of the trip and of course barfed coolant every time I stopped.  
After a closer look at the pulley, v-belt set-up it appeared to me that there may not be enough overall contact between the v-belt and the fan/water pump pulley v-groove.  My thinking being that if this is the case the effect would be that at highway speed the fan/water pump are not rotating fast enough to move the coolant and/or the air through the radiator.
 
All this being said I am wondering if there is a rule of thumb about how much of the radius of the pulley the v-belt should contact.  In my case this is a one belt system for both the alternator and water pump.

I am also in the process of fabricating a fan shroud and trying to balance all the information of electric fan vs. mechanical.  This set-up is on a 1934 Ford pickup hot rod with no fenders or hood and I lean heavily toward mechanical -- any thoughts?  

As far as Elect VS mechanical fans,I prefer elect.They move a constant volume of air at slower speeds compared to a mech. which varies per RPM. Highway cruising usually doesn't need either as air being forced through should be sufficient.A proper size radiator,good water pump,& thermostat along with a engine with clean water jackets,no head gasket leaks and no excessive ignition advance should run cool enough.I would guess that a problem with the belt would cause a squeal or at least destroy the belt in short order,though they should fit the pulleys properly.  

Yeh , I would tend to agree.You will probably get a slip if anything. The issue is not really to do with the speed of the fan/waterpump at highway speed,really you should get enough airflow through the radiator with just the airspeed. Plus you don't want to push the water too quick through the radiator as a lot of people think, you have to give it time to cool,otherwise you are just pushing hot water back to the motor.  

Just about the time you think you've checked everything two or three times and have done everything possible to stop an overheating problem with your hot rod engine, you discover something that makes you feel, how can I say this gently, stoooopid!  I have sweat bullets for several years now trying to figure out why my 401 Nailhead was running hot.  I started out with an electric fan as a pusher because I didn't have room between the engine and radiator for a puller.  That didn't work.  I just barely had room for a cheesy skinny flex fan to work with the pusher electric.  That didn't work.  I removed the electric fan thinking it may be blocking air flow and tried the cheesy flex fan only.  That didn't work.  I checked the timing again for the fifth time.  It was good.  I changed the thermostat from 185 to 160 then back to 185 then 160 and again back to 185, along with changing the radiator cap through several pressure ranges.  I thought -- well the engine is new so it will take a few miles to loosen up.  This is somewhat true as I have built engines in the past and found that around 1000 miles they begin to loosen up and run cooler.  Not this time!  Now comes the serious stuff -- I removed the cheesy flex fan, installed a larger diameter single groove water pump/fan pulley, cut off the front groove on the crank pulley, bought a new much smaller alternator and new alternator bracket which allowed me to move the alternator up and back on top of the engine.  All of this bought me room between the engine and radiator so I could install a fixed six blade fan with deep pitch.  Well now this should do the trick, right?  Wrong!  All my hot rod buddies were now telling me what I really need is a fan shroud and the guys that built the radiator for me are saying that the radiator is plenty radiator for the 401 shroud or not.  I'm handy, I built the car and some of the engine, so I build a fan shroud.  No small task in this case, because the grille shell/ radiator is a one of a kind custom unit that I built.  I even modified the bottom tank outlet because I (and friends) thought the outlet was causing a flow restriction the way it was.  A lot of work later and I've installed the new shroud and I'm all excited because I know this is it! Not!  By now I had drained and filled so much anti freeze that I actually installed a pit-cock on the engine block.  I lost count of how many gallons of anti freeze I actually bought.  I think a 55 gal. drum would have been a bargain!  Well the gauge was still showing 223 degrees F and I --- wait a minute!  The gauge!  Could it be the brand new gauge?  I ran the engine until it got up to 223 then checked it and the radiator with an infrared temp checker.  Upper tank 193, lower tank 143!  What the heck?  Next day I called the gauge people and discovered my sending unit was not installed in a proper manner.  It was not submersed in the hot coolant and was basically reading super heated steam!  I ordered a new longer probe and will re-locate it on the cross-over on the hot side of the thermostat.  Hope my dumbness helps some of you avoid this issue.