Very nice old school build up. I like seeing these old engines built into something special. Taking the center divider out of a dual plane manifold was a trick Chevy used on the L88 engine (the middle intake in the picture). I ran this with L88 heads on my Corvette for years.
But true to reputation, while it easy proven to improve higher rpm power it made the engine kind of finicky and soft at low rpm and Chevy recommended staggered jetting in the Holley with a different jet in each bore to make up for unbalanced flow with the divider removed. Interesting that it the case of the poly it boosted low end. Best I can figure out the BB Chevy has huge valves and ports and my heads and intake had been ported out further and port matched, and all of this plus the opened up plenum just kills low rpm velocity and response.
In comparison, the poly with its small ports and valves plus a stroker crank, must be pretty limited for air at all rpm ranges and really responded to opening up a big plenum area to feed each port/cylinder. You really built a killer engine out of this combination. Very cool and great work.
But true to reputation, while it easy proven to improve higher rpm power it made the engine kind of finicky and soft at low rpm and Chevy recommended staggered jetting in the Holley with a different jet in each bore to make up for unbalanced flow with the divider removed. Interesting that it the case of the poly it boosted low end. Best I can figure out the BB Chevy has huge valves and ports and my heads and intake had been ported out further and port matched, and all of this plus the opened up plenum just kills low rpm velocity and response.
In comparison, the poly with its small ports and valves plus a stroker crank, must be pretty limited for air at all rpm ranges and really responded to opening up a big plenum area to feed each port/cylinder. You really built a killer engine out of this combination. Very cool and great work.
