Impala Tech - View Single Post - 427 Engine rebuild
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post #5 of (permalink) Old 11-30-2019, 09:49 AM
Big Dave
Join Date: Jan 2006
Posts: 12,756
Pull your numbers matching engine and put it in a bag. You can store it on an engine stand or under a bench. Then buy a 454 out of a light pickup and rebuild that as a 496 or bigger motor.

Big blocks are not very efficient on today's pump gas. To get anything out of them you have to increase the displacement. A Mark IV BBC can be easily stroked with a 4 inch stroke crank (so a 454 stroked a quarter inch to get to 496 cubes by boring it 0.060" over) and a more modern Gen V or Gen VI block can be stroked to 4 inch to obtain a 518 cube motor. You will need a new oil pan either way as only a light truck has had a 454 under the hood since 1974. And the truck pan will not fit a car chassis (this goes for all of GMPP's 454 or 502 crate engines as they all ship with pick-up truck pans).

You can recycle your entire top end or buy replacement aluminum heads. You want a roller cam because modern reduced ZDDP motor oil will fail; wiping the cam, if you try to use it with a flat tappet cam. If you want the cheaper flat tappet then you will be paying a lot more for ZDDP rich motor oil which usually runs $8 bucks a quart. So if you run the engine much over time you would actually save money installing a roller cam in the first place.

You can stamp the rebuilt block with your old numbers if you like them: though numbers won't make it any faster or more reliable. Your rebuilt truck engine will look just like your old 427 with the proper decals.

Big Dave
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