BoogerHog

Hey there sports fans!
Im new to these forums, and appologize if im re-hashing a tired subject, but i cant find any info on the swap im planning:
I want to swap out an old tired 454 for a 350 (probably longblock crate motor).
I have a '77 GMC High sierra camper special, an original california truck that had a 454 with the ultra-rare, ultra-undesireable CA smog package. I got some bad valves, and my cam is going flat. After sitting almost a full year without being driven or started, i tried starting it and heard a terrible banging and loud snap from inside the motor, and now it wont turn over. I dont want to rebuild the 454 because i dont need that type of power and want better MPG, not to meniotn my other truck and my chevelle both have 350's, so it would be nice to have parts compatibility. I see TONS of threads on swaps for small block to big block, or even 1 for 1 swaps, but nothing for from big to small. any info would be appreciatted. Ive done a 327 to 350 swap in the chevelle, easy. Im anxious about what hidden problems or costs will there be, and hope to hear from someone with 1st hand exerience or more "in the know" than myself. Thanks Folks! -BoogerHog

hicksvilleshick

I can't say I've done it recently, but if I remember correctly it's pretty straight forward. You want to make sure parts match up, mainly the bellhousing with the block and motor mounts, beyond that it's just a matter of having proper wiring. I don't know if your 454 was HEI or not, but I'd at least go with HEI over a coil setup (memory fails me if they that era was coil or HEI) worst case if your finding the sb to bb write ups most the info should be right there, look at what needs to change from sb to bb and reverse.

As for the smog stuff, good luck I'm in one of the states we ain't gotta worry about that crap, so it's usually just deleted.

mgibbons

How did your swap go? I too will be swapping an old 454 for a new 350 crate and want to know the problems that lay ahead.