350 to 454

[mkslam]

I have an 87 k 5 with a 5.7 TBI. putting in a 87 454 that has carb. what do I need to do to run tBi on big block?

 

[gpmorgan]

If the 454 is a stock engine, I would get an adapter plate and use the tbi from the 350. If it runs to lean you could always get a 454 tbi unit.

 

[gpmorgan]

Welcome to the forum Matt.

 

[HotRodPC]

I've been wondering some of this myself. I'm aware the 350 TBI intake won't fit the old school pre 86 heads with mods. But what about 454? Can't you find a TBI 454 intake and TBI unit, and it bolts right to the older 454 heads, like the peanut ports heads that come on say an 84 model or are 454 TBI heads different too?

 

[kleedus]

the tbi 454 uses a spacer adapter to put the tbi on a carbed intake the adapter and tbi shows up on ebay pretty often

put the 454 tbi and adapter on and get a chip for the 454 ebay is also a good place to find the chip for the 454. and transfer the 350 sensors they will all work on the 454 its that easy

the 454 tbi adapter and computer chip is all you will need to get

I done it to my suburban

 

[HotRodPC]

the tbi 454 uses a spacer adapter to put the tbi on a carbed intake the adapter and tbi shows up on ebay pretty often

put the 454 tbi and adapter on and get a chip for the 454 ebay is also a good place to find the chip for the 454. and transfer the 350 sensors they will all work on the 454 its that easy

the 454 tbi adapter and computer chip is all you will need to get

I done it to my suburban

So you're saying, it uses the same TBI harness as the 350 too, but just change the PROM chip and use a TBI adapter on the OEM intake manifold? My 454 is an 86 model.

 

[Irishman999]

The big blocks are more interchangeable than the small block stuff.

The easiest way to do that swap has already been mentioned, the adapter plate for the throttle body. My gen IV engine came with a cast iron intake for a quadrajet that had a huge adapter that flows coolant through it, thats how it came from the factory.

For an intake I went with a Edelbrock performer II spreadbore. So far all I had to do to run TBI on it was get the steel adapter plate and drill/thread a hole by the thermostat housing so I could run a coolant temp sensor. Its essentially what comes from the factory anyways just more efficient parts.

As far as stuff from your small block transferring over, I would not count on that. I learned that the big block throttle body is bigger, the engine is very hungry for air even with the bigger throttle body so choking it down that much more is not a great idea. I would go to a wrecking yard and pull an assembly off a big block, mail that **** to Jims86 and pay him to rebuild it. He did an awesome job on mine, it even came back with an adjustable fuel pressure regulator so I can crank up the fuel.

If it would help you out I can snap some pictures of all the tbi components I have on my big block.

 

[bucket]

So you're saying, it uses the same TBI harness as the 350 too, but just change the PROM chip and use a TBI adapter on the OEM intake manifold? My 454 is an 86 model.

Precisely.

 

[kleedus]

ya a tbi 4.3 v6 350 and 454 can use the same harness might have to adjust the length of some wires.
I put a 454 in my 90 suburban and used the 350 harness with no modification

I went to the junkyard and got the brackets that bolt to the intake for the sensor things off a tbi 454 and the tbi and spacer

I fired the 454 in the sub but never put exhaust on it and never really finished the motor install. so there might be a couple small things I may have missed but the 350 harness will for sure work.

and as long as your 454 has a stock or mild cam it should work fine

I just searched for these pics to show what you will need to get found the on the web so not sure what year the parts are

 

[kleedus]

oh ya I deleted the egr and all emissions I used a edelbrock non egr intake

so I am not sure about the egr as long as you have one on your intake it should work.

 

[HotRodPC]

Well, I don't wanna hijack OP's until he gets the answer he's needing, but what I was thinking, is I could take my 454 out my C20 and put it in the Burb. hmmm, but then again, still have expenses for adapters and chip, and then registration. That kinda leaves me in the same boat as if I could have gotten those $50 heads last week to get it running. Fuggin sucks to be this broke. But good to know. My 454 just might end up in a 4x4 K20 someday and be TBI, or I just might TBI the C20 later on. Nice to have the options with the 454.

 

[RetroC10Sport]

I know the mounts are different, the 454 will sit lower than the 350 and cause problems.

 

[HotRodPC]

I know the mounts are different, the 454 will sit lower than the 350 and cause problems.

I do believe all you do is get 454 motor pads to bolt to the frame and the issue is resolved.

 

[bucket]

and as long as your 454 has a stock or mild cam it should work fine

So you're saying you can use the 350 chip too?

I know the mounts are different, the 454 will sit lower than the 350 and cause problems.

I've also heard it will cause problems, but never seen or experienced it myself. I think as long as the rubber mounts are in good shape then everything works ok.

 

[kleedus]

it will run with the 350 chip but it will be way lean and not run right I wouldn't do it that way.

I was just saying the tbi will work on any stock cam or mild cam 454