305 to 454 swap

[BBC Chevy Man]

Hello everyone, I'm new to the forum. Been lurking around for awhile as a guest and I must say this is one of my favorite sites for the square body trucks.

Anyways, I have a 1979 GMC 1/2 ton 2wd with the old and slowly getting tired 305 in it and I am wanting to do a 454 swap into this truck. This will be my first engine swap in a square body and I am wondering if this is going to be a direct bolt in, or will I have to modify the engine mounts to put this engine in? Also will the old Turbo 350 tranny be a good transmission for this swap?

Thanks,
BBC Chevy Man

[champions53]

Another new guy here, but as far as I know you shouldnt run into any problems with mounts. Ive been involved with a couple bbc swaps in these trucks but as far as i can remember you shouldnt have a problem. Th350 as long as it is a good trans will be fine, Ive had several behind bbc's that did fine.

[SSC's76]

It will drop right in no issues. Just make sure you have all the parts and accessories to make it work. The 305 cooling system may not like the bigger engine but the TH350 should hold up just fine as long as there are not current problems with it.

[BBC Chevy Man]

Thanks guys. The 454 is coming from a 1978 chevy crew cab donor truck, so I'll have all the parts I'll need for the swap between the two trucks.

[87GMCChris]

Could i do the same, but with TBI(since mine is an 87)

[champions53]

From what i can remember the TBI isnt really an issue to swap either. The only TBI swap Ive done was swapping out a 4.3 for a 5.7 and it was a peice of cake no wiring to swap. Someone else that has done this could chime in a correct me if Im wrong on it not being an issue to swap in a tbi 454

[cheepin]

I swapped a 454 into a '79 Suburban that had a SB400.It bolted right in.But a couple of issues were the stock 454 tall fuel pump didn't fit.The stock 454 cross members and motor mounts mount the engine higher up.I ended up using a shorter pump out of a '70 Malibu with a BB in it.Also the stock cooling didn't cool it enough.I had to find a BB radiator.

[cheepin]

Originally Posted by 87GMCChris

Could i do the same, but with TBI(since mine is an 87)

Is the 454 TBI now?The stock 454 TBI is bigger and the ECM is programmed for this.Also is the 454 from in front of an auto or manual.The ECM controls the shifting of the auto.So if the ECM is from a manual you may have problems with the shifting if it will shift at all.

Check out the TBI swap thread here.It has great info!You will see I have been asking lots of questions there.

[1987GmcSierra]

Originally Posted by champions53

From what i can remember the TBI isnt really an issue to swap either. The only TBI swap Ive done was swapping out a 4.3 for a 5.7 and it was a peice of cake no wiring to swap. Someone else that has done this could chime in a correct me if Im wrong on it not being an issue to swap in a tbi 454

Notable problems as i hav edone quite a bit of research concerning this subject The wiring Harness from a V8 Tbi truck can be used but ofcourse u need a donor computer and chip for the 454 as i have an exact same year 87 gmc suburban that a donor and u need a harness from TurboCity.com about $50 with shipping to be able to use the idle air sensor plug on the v8 to match to the 454 idle air as far as i can tell other than that and changing motor mounts it should fit right in between the frame rails im in the process of gettin a big block in between the frame rails so as time goes on feel free to ask as many questions as need i will answer them Thanks hope this helps




Well First off the motor mounts were diffrent for the 4.3 and 350 the 4.3 harness was 2or 3inches to short so i ended up using a tbi harness from another parts truck that came with a v8 the 4.3 to 350 swap was ok not all that hard but make sure u have a complete parts truck to use as i also found out that the 4.3 power steering pump braket was diffrent than a v8

[TeXaS 86 C10]

anyone done a 572 swap ?

[87GMCChris]

I don't have the motor... lol, i was just wondering what would be easier. Was considering the 327 carbed i haqve laying in the garage rebuilt. But alot of work to get it to work, done lots and lots of research on that. Just wondered if a 454 with tbi would be easier. These are plans for down the road.... way down the road. Thanks, though.

[87GMCChris]

Originally Posted by cheepin

Is the 454 TBI now?The stock 454 TBI is bigger and the ECM is programmed for this.Also is the 454 from in front of an auto or manual.The ECM controls the shifting of the auto.So if the ECM is from a manual you may have problems with the shifting if it will shift at all.

I don't have the motor, as described in the post above. But... the computer doesn't controll my tranny, its a th400. No wires anywhere... unless you are refering to the proposed doner vehical?

Chime in anyone who has an 87 th400... i am possitive that its not ecm controlled, no?

[grinch4om]

a donor vehicle for all the widgets and brackets make life so much easier...