Is it possible to pin/stich a crack in that location?

     This particular type of failure does not lend itself to pinning, in my opinion.   

     Probably the best repair outcome would be brazing of the crack separation, but the heating required of the casting, though obviously less than if attempting to weld it, would corrupt some of the as currently finished machine work in this example.

     Scott.

       With the 351C "Big-Port" 4V cylinder heads it is the modifications of the area below the seat and particularly the short-turn radius that will provide the greatest effect for the effort but forth; you can in all but the case of the greatest efforts pretty much ignore the rest of the port.  Simply stated, all of your efforts would be to aid in the reduction of interference in the process of the atmosphere traversing through the passage, the inlet port runners though arguably are not the most efficient are of substantial area, and since the actual seating surfaces between the opening and closing flow control valving imparts the greatest restriction, the closer to this that efforts are extended the greater the gains. 

       Specifically, the O.E.M.'s 90-degree cut below the 45-degree seating angle (note that the original O.E.M. machining did not incorporate a 60-degree angle) creates too great of a change of direction within in the distance, this causing the laminar flow in close proximity to these surfaces to be lost, this first increasing the boundary layer and then inducing turbulence, thus an effective reduction in functional area, particularly at the higher velocity rates.  Therefore generally it is accepted that in these instances, a larger valve head diameter will provide one the opportunity to correct this. 

       But then yes, in the case of the 351C 4V heads (those w/ 2.19" valves), they already present generous dimension, thus creating other possible concerns, so some conservatism is generally needed here as compared to that of for example the typical in-line valve head examples. Therefore, as stated by another, if your needing to purchase valves anyway, and if the job were in our shop, I would advise bumping the diameter up a bit; just that which would prove necessary to provide the area required for a better resultant effect from the valve job, particularly if bowl porting/blending is not to be incorporated in the effort, but this sum specifically would need to be established by the one executing the work on those castings.

        And while on the topic of attempting to better the flow in the port, and with the thought of "transitions" and their possible negative effects, note that the greatest offender on that port tract is the 'short-turn' radius, which actually suffers from even qualifying as such, rather there is presented an absolute 'shear', which presents the worst possible effect on attempting to avoid inducing a turbulent result; so if porting is permitted, effort here will aid tremendously even if one doesn't do much of anything else in the way of porting.

        Scott.


 

       

      It's not a C6, but regardless I think the outcome would be the same.   

      Scott.

There are heavy duty solenoids that look like a Ford stocker that are designed for high amperage constant duty, one use is in the cranes on service trucks-

     Another, perhaps more readily available source closer to our market would be that from the recovery winch (e.g. Warn) companies.   

     Scott.

I was wondering if I should put a fuse close to the battery. I have a 200amp fuse do you think that would be big enough...................                                     

      It would seem that a fuse would be a good idea, but it isn't standardly practiced; consider it somewhat as the electrical service drop coming from the utility company power pole to the service/weather head on your house (even to the service disconnect) as this is, as a singular circuit, unfused. 

      And as far as to the ampere value required, check the amp draw on cranking (hot), I think you'll be surprised to find that 200amp just might not cut it!   

      An additional consideration, or perhaps confusion, particularly in the observation of this automotive wiring execution, that as often practiced by the O.E.M.'s, is that they understand that this is an 'intermittently' high amp circuit (only when the starter motor is engaged) and with that understanding they take advantage of the heat sink capacity of the wire thereby allowing over-amping the wire for short durations.  Proof, is in if you operate the starter for excessive durations, or ever had a starter out of your control stuck in the cranking mode, the wire lead to the starter will get hot or even literally melt and burn the insulation off the cable!   

      The same limited duration "over-amp" loading of the circuit (cheating! ) is also practiced in other equipment and structures and is typically addressed with "time-delay" or "slow-blow" fuses and circuit breakers; and this is another consideration in the inquiry of: "is this fuse big enough"?   

      Scott.

     In the opening on the video displaying the two examples of the Ford GAA's, the one to the right actually appears to be either a Ford GAN as utilized in later M4A3E2 Sherman Tank and the ill fated T23 Medium Tank, or GAF model which was produced later, more popularly for the M26 Pershing tank.   

     For additional study:   https://www.theshermantank.com/wp-content/uploads/Ford-GAA-V8-Data-Sheet-beta13.pdf   

     I have a GAA example  ,  that I'm trying to figure out how it'll fit into my '55 T-Bird!     But I just haven't come across the "adapter-kit" yet!   

     Scott.

Question for Scott- What would be your preferred setup?  I like to keep things as simple as possible.   I have the big '68ish aluminum Griffin radiator and was originally thinking I would put a shroud on the radiator with a flex fan (simplest),

     Yes I agree, it would seem that one should always start with the simplest possible solution first, and then prove that it is going to be necessary for something more complicated, more function failure prone, not to mention likely more expensive (one way or another).

     I would attempt the mounting of the largest diameter fan based on space permitting (often in the '66 Mustang it is the lower radiator hose exit from the radiator that proves the first limiting factor we've moved these over 'some' in the past, don't know where yours' is?  ); this fan generally of what we used to call an "R.V." style flex fans (deep-cupping blades shovel more air!  ) perhaps something along the line of this:  https://flex-a-lite.com/17-inch-silver-flex-fan.html  (but do note that they are available in different diameters, and yeah, along with the aluminum radiator a coat of semi-gloss black paint!  ); this mounted in conjunction with a well designed fan shroud (if not familiar with what makes for a better design do some homework  ); with proper positioning (centering & exposure) of the fan blades in relation to the shroud; then with turning speeds adjusted with different drive rate belt pulleys (note that these fans can produce quite a bit of noise (by-product of moving lots of air!  ) at higher turning speeds, but remember your changing the water pump speed at the same time so it proves to be a balancing act   ) as the goal is have the fan and pump turning at the speeds required in their respective responsibility in the cooling function, but any faster can prove to produce negative returns, including if only excessive parasitic drag on the engine (less H.P. for turning the rear wheels  ); and then some air motion management under the hood, this particularly in attempting to limit the sum of air that can enter the engine compartment and under the vehicle without having had passed thru the radiator (this is one of the major problems of these older chassis, as air circumventing the radiator into these areas decrease the required pressure differential to aid in the air flow thru the radiator!  ).

      So, the solution doesn't actually present itself as simply as one might have wished, if only as each instance is unique, but often in the effort to accomplish something in the simplest most efficient manor it's mostly just some thought effort, and acquiring the necessary componentry for the execution; oh, and yeah, probably involves a some of "trial & error" too!   

      Scott.

I started with a .......................... . Next attempt was ...................... I finally got the temp to stay under 190 using a Derale 7 blade 19" clutch fan/custom shroud (Hayden custom shallow clutch). The temp would start to creep up with the AC on so I installed a 16" Spal pusher fan that comes on with the AC on.

     We have been trough this time and again over the decades at our shop here in Florida (it does get hot & humid!  ) and this is pretty much the normal process that many of our customers have followed (though also including a flex-fan vs. just the clutch-type) and the final conclusion established in instances where the cooling systems' capabilities are truly being tested.   

     These repeated experiences are what led to my previous statement of:

      In these older type chassis, for one's typical "street car" use applications, and with consideration of what is typically marketed as,  I consider electric fans as best utilized as being "supplemental", this to the existence of the best execution of the mechanical fan first.       

     Scott.