Mike- I can tell you a few things I've done to the '58 Tri-Power engine (still '58 heads) in my '59 GMC, but unfortunately I don't have performance numbers (never dyno'd nor raced). I can only say that it's significantly more powerful than the Pontiac engines I built 55 years ago.
> Eliminated bathtub chambers, opened wall around intake valve
> D-shaped dish in piston crowns (for 9:1 C.R.) which provides generous squish area and good volume-to-surface-area ratio
> Un-siamesed center two exhaust ports on each head, so long branch manifolds are as effective as intended
> Aggressive HR cam
> Precise crank-triggered CD ignition
> Total Seal ZGS rings, fairly narrow
The low-rise Tri-Power manifold is the main power limiter for this engine.
I don't remember how close to the the original 347 c.i. Zink's engine was.
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Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons?
... or has built a record breaking DOHC hemi four cylinder Pontiac?
... or has driven a couple laps of Nuerburgring with Tri-Power Pontiac power?(back in 1967)
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