[Just repeating some of the info already provided…was posted while I was looking up some info to refresh my memory and got caught up in the details
.]
According to Steve Christ’s How to Rebuild Big Block Ford Engines, page 32, he says that hydraulic lifters are used on all FT engines, and have the standard FE oiling system with
oil galleries drilled accordingly. Some other FT differences are:
Larger distributor shaft bore to accommodate a larger
oil pump drive shaft.
Thicker main bearing webs and additional ribs in between.
Larger diameter crank snout (1.75” vs 1.375” for FE), and thicker flywheel flange.
Larger counterweights on forged FT cranks, and external balancing at the flywheel or damper is required because crankshaft to crankcase clearance is insufficient for even larger counterweights that are needed with the forged crank.
The pistons have a smaller compression height (wrist pin center to top of piston) of 1.757” vs 1.775” for the standard 390.
There are several other specifics and differences (ie, heads, valves, etc.) that I think you would just want to get the book, which has pictures, charts, etc., if you are considering using a 391. And you may want to check out ford-trucks.com and the FE Forum website for more info.