Thread: olds 425 rocket

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iv got a 425 ultra high compreson super rocket thats what it
says on the air felter i was just wounder if it is a rare engine.
Im going to turn it in to 455 if it is not rare. thanks

doubt it. if ya want to keep it ultra high compression, as olds put it, use the same heads and the same cc pistions, there probably flat tops possibly that is on it.

that engine has probably 10.5 to 1 compression.they required leaded 101 octane gas and did'nt come with hardened valves,because the lead was the buffer to cool the valves.thats what the red stuff was all over the carbs.lead!they were good engines but a 455 is a good replacment.they can be built but the cash man the cash!