Putting a 454 TBI in place of a 350 TBI?

[82355]

Can I use an existing 350 TBI harness to run a 454 TBI? I know a couple of connectors are different, but I assume it is just the connectors? Can I use a 454 PROM in a 350 TBI ECM? Any other issues I may run into?

Martin

 

[b454rat]

I was gonna do this swap couple times years ago, and from what I can remember, the harnesses are the same except for IAC and TPS plugs, but certain years thought they are the same. 7747 ECMs are the same, so you could just swap them out, or get a chip to run the 454 off evilbay.

 

[454Sub]

All connectors are the same, well they were on my swap, except the IAC plug. I cut mine off the donor 454, and soldered it into my 350 harness. I actually ran mine with the 350 prom and everything with just a fuel pressure regulator, and it ran fine. But to answer your other question, yes you can swap the 454 chip in place of the 350 one.

 

[82355]

That is what I figured. Just wanted to check.

Martin

 

[4X4HIGH]

I have first hand experience trying to run a 454 TBI on a 350 and it will barely run because there is too much fuel. Now if you run the 350 injectors in the 454 TBI it will run but too lean because of the extra airflow. Trying to run a 454 prom won't cut it either. I had Brian at TBI chips burn me a chip to run my 454 TBI on my 350 and it's perfect.

 

[82355]

No, I am wanting to remove a 350 engine from a Blazer, and replace it with a 454.

Martin

 

[4X4HIGH]

No, I am wanting to remove a 350 engine from a Blazer, and replace it with a 454.

Martin

In that case all you have to do is repin the IAC and possibly the TPS switch depending on the year of the TBI and you're good to go.

 

[82355]

Yeah, that is what I kind of thought. I went back and re-read my original post, it wasn't very clear.

Martin

 

[Greg Ducato]

I have done the same swap, used the 350 harness with minor changes and used the 350 computer with a custom chip, though I did run it with the 350 chip for a bit.