The 389 is the "forgotten *****". The short block is very nearly identical to 400 except the final bore size (4.062" vs. 4.120"). Same crankshaft, etc. Using an Eagle "stroker" crank with "custom" pistons makes a VERY strong 458 CID engine.]
Q: 458 cu.in. Is this what you get with an over bore on a 389 and dropping in a 455 crank with machined journals? I'm gonna have to get my calculator back out.
[There are three basic motor mount "systems" from '59-'79. The "two-bolt" mount (pre-'70) is the most common. All the blocks from '70-mid '75 have five mounting holes, supporting both the two-bolt mount AND the three. Later blocks only support the three-bolt mount, and probably should be avoided. The 557 casting (last 3 digits) is the "weak" one. The 988 is much better ('75-up).]
Super helpful information. Now I need the actual block.
[As heavy a car as the '50 is, the larger cubes would be desired. If you "lucked upon" a 421, THAT would have "cool factor" beyond any of the others. They're tough to find, though. A 389 block with the 4.25" stroke, the '67-later heads (have the "good" valve angle, where the earlier stuff is 19 degrees) and a '66 TriPower unit on top (all available "new" now), would be the ultimate Pontiac "street rod" arrangement.]
Oh man, it really would.
[NOTE: The "advantage" of a shallower valve angle is a better "approach" to the cylinder through the intake path, providing a straighter "shot" at the center of the cyinder (intake) and "rolls" the exhaust valve over to make a straighter "shot" at the exhaust port. The practice of "angle milling" small block heads stems from the desire to improve both of these issues. It's not as significant for the small block's exhaust, as that port is excellent. The Pontiac needs all the help it can get on the exhaust side.]
That helps, I think this helps me narrow my search for the block to head combination as this angle is not common to all years. Thanks.
[TH400 is the minimum level of transmission that will "live" behind a high-torque Pontiac. TH200-4R has been known to "take it" if the internals are upgraded. We've seen a lot of trouble with both TH350 and TH700-R4, simply not up to the task.]
I'm still trying to get a handle on the manual vs automatic to block thing. The block I choose will dictate the type of transmission - to a point. Some blocks are for manual transmissions and others are for automatic, right? At any rate its good to know what to look out for should I go with an automatic.
[You should consider getting Jim Hand's "How to Build Max-performance Pontiac V8s" published by SA Designs.]