Comment that it has to be able to breath is correct. Not only the exhaust, the heads and size of the valves is critical. If you are using the stock head that come in the truck, it has the smallest valves ever used in the Y-block. Putting a 4bbl on it is a waste and will likely hurt performance. You need the heads with the bigger valves from the earlier T-bird engines. The guys on the 48-56 forum or maybe the y-block forum can give the actual numbers of the heads, I can't recall. Stock cam is built to pull stumps, you can get an improved street cam from John Mummert that will improve performance more than a 4bbl.

 

Oh boy, I've been called out.

A smaller, reasonably sized vacuum secondary 4 barrel should be fine. If tuned properly, it should help with economy since it will effectively be a small 2 barrel until you get on it and it will give you just a little more potential at the top end. It would be good compliment to the dual exhaust.

Regarding fuel injection, I haven't gone there, yet, but many of the systems have gotten to a point that they seem extremely easy to set up and just about anyone who can turn a wrench can get it installed. The potential problem I can see is for people who are computer illiterate. When you start to have problems, and you will eventually, no matter how good the system, much of what you know about trouble shooting a carb will be out the window and if you are uncomfortable with a computer, that could make it very frustrating to fix problems. This will depend to some degree on how the software is designed, some will certainly be easier than others to diagnose.

A '59 should have large valve heads but it's also 59 years old and can have anything installed by now. Determine what you have, Cylinder Head Chart.

If the cam was reused, then it's not the worst there was but it is still a smaller, detuned version vs the '57 cam. If it is a new "stock" cam , then it may be worse than the actual original - I suggest the standard 1957 spec cam or a smaller aftermarket cam, like an isky 301444. Or, even better, call your favorite cam grinder for a custom grind to fit your specific use. The '57 cam will be good for truck use. The Isky, I think is a hair bigger so it may not be as good for that. And if it will not really be used for truck duty, maybe go a little wilder. Because the cam is pretty difficult to swap in a Y, it is something you want to get right from the beginning and it just doesn't make sense to me to go with anything smaller than the standard '57 cam.

 

 

Aftermarket carbs are fine if they're tuned correctly. If it's just bolted on without any regard to the tune then yes, it may cause problems. I've yet to use one that required more attention after setting it up right. The current one, Holley 570, has been installed for 9 trouble free years.

Holley still produce a 390. If a carb with larger throttle bores is used, it's not a big deal. Someone, I think Speedway Motors, sell a tapered carb spacer which will allow you to install a larger bore carb onto the stock intake. Or, really the best option, is to open up the intake and make it more like a modern one with two ovals instead of 4 holes. Use epoxy to flatten out the valleys of the carb mounting pad after that is done.