350 to 310

[884x4310ci]

So if I swap a tbi unit and computer from a 305 truck would I be good ? Also my truck being a 93 I have a 4l60e and not a 700r4 so I need to look for the trans as well.

 

[Supercharged111]

So if I swap a tbi unit and computer from a 305 truck would I be good ? Also my truck being a 93 I have a 4l60e and not a 700r4 so I need to look for the trans as well.

Yeah, and make sure the knock sensor matches the combo as well. Have you tried sitting there until it gets up to temp so it'll lean itself out? Not the correct answer and there will be driveability quirks but would at least give you an idea of what else may be going on if anything.

 

[Schurkey]

The 305/5.0 injectors would be much closer to what the engine needs compared to the 350/5.7L injectors.

I don't have too much to do with PROM and computer changes. For all I know, the computer is the same from 5.7 to 5.0; but the PROM is almost certainly different. I'm sure the knock sensor is different, too.

As said, nurse the thing along as best you can--then when it's fully warmed-up, you can verify ignition timing, you can check EGR operation, you can connect a scan tool to look at the data stream and verify sensor operation.

While you're in there, make sure your fuel pressure is adequate. A cranking compression test would also be nice.

When everything else is right, but the engine still doesn't run properly...you know you need PROM and computer changes.

 

[vr1967]

I believe the memcal code you need is BDFK for your prom, for a 93 with 5.0/4L60e

 

[884x4310ci]

I found a idle screw. And to drill out a cap to get at it. But I gave it about a turn and now she can idle. If the factory tach is right it's 950 rpm. Sounds about that as well. It's rich though. A set of 305 injectors would be better I think.

 

[PlayingWithTBI]

And to drill out a cap to get at it. But I gave it about a turn and now she can idle

That's not the way to do it. At best it's a band aid, at worst, you'll burn up the IAC stepper motor. You need the correct injectors AND MEMCAL, BCC, PROM, Chip, whatever you want to call it.

 

[884x4310ci]

For sure. I agree. I will try to get a tbi off a 305 and ECU after Christmas. So just the chip and injectors should fix the rich idle ? All the other sensors are good ?

 

[skylark]

I'm going to be the black sheep on this one. I dropped a 95 305 long block in place of a 90 350 with zero changes and it ran beautifully. Was tuning spot on everywhere? No clue. It ran well and had pretty good power.

 

[Supercharged111]

I'm going to be the black sheep on this one. I dropped a 95 305 long block in place of a 90 350 with zero changes and it ran beautifully. Was tuning spot on everywhere? No clue. It ran well and had pretty good power.

We have guys in my racing class running truck 5.3 motors on LS1 tunes and they do fine as well.

 

[Nad_Yvalhosert]

I cant understand your non running issues. My '88 was a 4.3 stick 4x4. I swapped in a 305 TH400, wiring and PCM. Used the 4.3 fuel pump. Started, ran great.
Blew the motor 2 years later. (Seems it doesn't like sustained 5000 RPM in the mud)

Here's my point. I installed a 355, used the 5.0 knock sensor, 5.0 TBI, 5.0 PCM and chip, still got the 4.3 pump. Fired up perfect, 1 wire O2 sensor providing data for fuel trim corrections. Damn thing gets 13MPG on the highway with 285 tires!
The TBI system is so forgiving and self learning, you must have something else wrong