All good points, John. GM inline engines (not just stovebolts) such as GMC, Buick, Pontiac, and Oldsmobile from the late 1940s and early 50s were all massively over-engineered. For instance, those main bearings that get progressively larger toward the flywheel end of the engine turned out to be an unnecessary, and expensive method of getting the job done, plus they added an exponential level of difficulty to a complete rebuild. Ditto for the connecting rod journals- - - - -they're way oversize for the job they need to do. Changing main bearing size is doable, but it involves machining operations that most shops either aren't equipped to do, or they just refuse to because of the labor time involved. Changing stroke and rod journal size is a much simpler job that only involves one machine- - - -a crankshaft grinder. Stroker engines have been around for many decades- - - -my father was doing it on flathead Ford dirt track engines in the early 1950s. By reducing the size of the connecting rod journals and offsetting the centerline, more stroke (and torque) can be built in- - - -sometimes a LOT of it. There's also a small, but significant reduction in turning friction with the smaller rod bearings. The 1/16" stroke change involved in the engines I have described above increases torque- - - -it won't be massive, but it should be noticeable- - - -especially on the 216. The primary advantage is to enable the use of decades-newer, new, not reconditioned parts like the big block Chevy connecting rods. Also, manufacturing tolerances and metallurgy have improved pretty dramatically since the 1950s. Modification of other internal parts is also possible, such as adapting to different (less expensive) valve lifters, roller bearings in rocker arms that reduce internal friction power loss, and solid state ignition systems that actually work (NOT Pertronix!)
To the "numbers-correct" restorer with a library of dusty parts and service manuals that Fred Flintstone's mechanic once used, these modifications won't appeal to him at all. For the weekend cruiser or the guy who still does real truck stuff with his rig, the advantages should be worth the effort- - - - -a one-time "bite the bullet" expense to build an engine that ends up with more power, more accessible (and probably less expensive) rebuild parts- - - -all inside an engine that still looks "original" to the casual observer. That sounds like a "win-win" situation to me!
Jerry
