Thread: 455 olds in an 84 cutlass?

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I can't answer all your questions, but here's what I know. The only difference in the "small" Olds and the "big" Olds motors is that the "big" motors have a taller deck height to accomodate the longer stroke. Motor mount locations and bellhousing pattern are common to both type blocks, so a 400, 425, or 455 (all tall decks) should bolt into your Cutlass if you use a set of motor mount stands made for any of the Olds motors that was OEM in the 1978 and later G-body. As for clearance, the 455 will be taller and wider due to the taller deck, and I can't comment on what will fit the Cutlass in that regard.

Bob

with ac i'd say it will be a little tight.