TBI SBC swap for 4.3 TBI Monte

[81cutlass]

Have a mutual friend that bought an 86 Monte EFI 4.3 in nice shape with a stuck 4.3 that has sat for a decade or two.

I suggested finding a SBC to drop in since the 4.3 is stuck and needs at least rings and a hone. He asked about an LS swap but since he already has an EFI monte some of the stuff you would have to do to swap an TBI SBC is already done and its just easier. He doesnt want a race car he just wants something that runs and is fun. Basically a TBI 350 is $250-500 that has a warranty from a salvage yard and can be running in 2 weekends whereas an LS swap will cost $1500+ and take months.

What year TBI 350 would be a good fit? He needs obviously the long block, manifolds, and intake assembly. The EFI 4.3 accessories bolt on but didn't TBI SBC of those years get a serpentine belt drive?

He is looking for the easiest TBI 350 that can go in with minimal work and minimal parts hunting.

I think an 89-93 cop car caprice L05 TBI 350 is the best drop in option? How much harness rework is needed, can the TBI Monte harness be used and just swap ECM from the caprice? I think 87+ F body 350 is out since they are all TPI. I read the cars get roller cams, do all cars (caprice, roadmaster ect) also get serpentine belts? What about C1500/tahoes? Will the V8 manifolds from a car or pickup generally drop in the same spot as a 4.3 TBI g body?

 

[clean8485]

What about a 350 TBI out of an early '90s Buick Roadmaster? Should be able to retain the serpentine belt drive setup as well.

 

[81cutlass]

Found out he is getting a $100 running 305 TBI out of a 92 pickup.

So does the pickup TBI and engine sensors just plug into the TBI 4.3 harness?

 

[ssn696]

He will need the ECU/chip for the engine. The fuel maps are engine-specific. Others may weigh in on the 87-92 split in control system designs.

 

[spidereyes455]

Most of the sensors will plug in though the tps won't, they changed them around 89 I think at least on the f bodys anyway. Some wires would need to be lengthened as a 4.3 is shorter than a sbc. He could probably get around the tps issue by using the 4.3 tb and swap out the injectors with the 305 ones. The ecm will need to be swapped for a v8 one and will need to check the pinouts on the ecm plugs to see if they are the same as the donor ecm. If it makes any difference I used a 91 firebird tbi harness and ecm on my GP it fit well but it required a bunch of wires to be moved in many of the connectors. Having a factory shop manual for the monte and one for whatever the donor harness and ecm comes out of is essential.