I have a 1969 Corvette Convertible 4 speed with the L46 motor 350/350. What parts would need to be changed if i wanted to put a 427 or 454 motor in this car? The car also has the factory side exhaust.
Your Corvette from the factory did not come equipped to handle the heavier 427/454. First what is needed is the large block suspension springs. I think the shocks will need replacing, also. The motor is larger so some of the steering stiff will need repositioning. The entire front suspension geometry will need to be replaced with larger parts. The radiator will need to be larger, the hood will not fit so a new one is needed, factory or after market is your choice. The larger engine will have complex exhaust clearance issues. The connection to the side exhausts may be larger for the big block. If it's power you want, I built my 350/350 up to have more HP that a stock crate big block, with faster revs, and no modifications needed although I did do it. Consider a 400 crank (stroker kit) cam, heads, larger or dual carburetors, or even an EFI. I put in electric fans, larger radiator, dual quads, Edelbrock high flow heads, bored out 0.040, new 5 speed, 2 1/4 stainless exhausts to Flowmax mufflers, and Hooker long headers. It is faster than the 69 427s, except the L-88, and has beaten the first reintroduced Z06 Corvettes with 405 rwh. Oh yes, I think the transmission will need to be changed out with the larger engine. Compare the costs. Mine is around 445 HP. $12 k on a new motor and all extra parts. The old one had three major cracks, got a bare block 4 bold main 350 and had it professionally built by a person that builds NASCAR motors.
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