Thanks, guys, for info on the 430 vs. 455. I've been learning a lot about these gems. So much power from such a light package! I'm now about one step from approaching my neighbor about his Riviera (the one parked in the weeds out back for the last 20 years).

One more question-- On a 430, what kind of compression ratio is needed to be happy with pump gas with (stock, ported) iron heads? With T/A aluminum heads?

graemlins/wavey.gif Hi Dave

With a High Compression Engine, Designed for Leaded Fuel, I Myself would not use any fuel under 92 Octaine.

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Tom Gallagher graemlins/shield.gif

Iron heads can stand up to 10.5 to one compression with 92 or 93 octane fuel if there is a good quench area and all of the sharp edges in the chamber are smoothed. Most people stay between 10 and 10.25 to 1 compression on the higher octane (92, 93, 94) fuel to be safe.


Identically shaped aluminum heads can usually sustain a point higher in compression then their iron counterparts. That would put the 92 or 93 octane pump gas limit around 11.5 to one compression with a smooth combustion chamber and good quench. 11 or 11.25 to one would be a safe compression ratio on pump gas with the aluminum TA heads.