help with 454 swap

[87sierra]

I'm pretty new to the whole engine swap thing and I was wondering if somebody could give me a detailed description of what would be needed to complete the swap from a tbi 305/400 combination in an 87 sierra to a 454/400 combination from a 1989 Chevy truck. I basically need to know what can be used from the 305, like the tbi and sensors, stuff like that, and what will need to be changed in order to complete the swap.

[SSC's76]

Your going to need to grab the ECM or at least the prom from the 89 454 donor. The sensors should work as long as they fit. If you are running a knock sensor that must be changed. Im not sure about the TBI havent worked on to may TBI 454's last one was well over 15 years ago. If memory serves it's a different then a SBC with some funky plate adaptor. I hope some one with a little more insight will chime in here Ive done plenty of TBI 4.3 to SBC swaps and know what works with them but never a tbi SBC to BBC swap.

[munice]

I recently went through this process swapping a 87 350 TBI for an 89 454 TBI, when I pulled my engine I took the whole engine bay harness from the 454 donor truck.. and yes you'll need the ECM. In my case going from the last year sqaure body to the 2nd year of the 88-98s they changed quite a few sensors (more wires etc) so I ended up having to join the new engine harness to the old dash harness (not fun at all) In hindsight it is waaaaay easier to just switch to a carb... unless you find a rare-ish 87 TBI 454 dually or similar but honestly for the mediocre performance that the TBI engines put out I'd never do this swap again... down the road i plan on rebuilding my big block for a carbed setup (although it does start up nice)

[87sierra]

Thanks for the replies and that was pretty helpful. I think I may just forget the 454 idea unless I do happen to stumble across an already tbi 454 since I don't want to go through too much trouble with this. I've researched the 305 to 350 swap a little and it seems like it would be a lot easier since I would be able to use most of my existing parts but what about the ecm and harness, would that still need to be changed or were they the same for the 305? Again thanks for the help.

[munice]

all the 305 sensors should work for the 350 you could even just swap the whole intake manifold from your 305 onto a 350 and you'd be good to go

[87sierra]

Alright thanks, I'll start looking for one of those then and save myself some time.

[78 Chevyrado]

The only thing specific to the 350 you'll need is the fuel injectors and the ECM. Get them out of a junkyard truck, burban or blazer. Everything else from the 305 swaps right over.

[87sierra]

Do you know what years? or does it just have to be a tbi 350?