STEEL

Recently obtained a 1989 Suburban, 5.7, TBI, 700R4, ugly as sin and beaten to hell. Its mostly a mud and abuse rig, and who knows what else. I know this is not an Fbody, but this forum has always had the most knowledge about the TBI and early TPI systems that I hope you'll forgive me. If it helps, I been here off and on with the 3 Camaros I had in Highschool and College.


Also, by doing a bit of horse trading, I think I got a pretty cool engine.
Block is an older 4 bolt main, non roller tappets, with the double valve relief pistons.
Cam is a Comp 268H
Heads seem to be the old "Double Hump" heads. Running the casting number (I can post it up tomorrow) showed them to be 69ish Z28 heads.

How much money will it take to get the TBI running this engine well? If I installed the TBI on this hot 350 without any tuning, what would happen?

Thanks for reading.

JPrevost

Here's the problem... the injectors will not be flowing enough fuel to feed that engine at peak HP. Cost break down: 255lph fuel pump, adjustable pressure regulator, tuning software and hardware can cost anywhere from $100 to 500+ depending on your style of either DIY or purchase some tuning help. Your mods don't scream trouble but the fuel delivery is a big deal. TBI is speed density meaning it calculates the air flow (and consequently the fuel needed for a proper air fuel ratio), it doesn't measure it. Any changes to the engine's breathing will dramatically change the volumetric efficiencies and put in you a pickle (either runs great at idle and runs lean up top or vice versa). A carb is the easiest way to get an engine running well and if you don't plan on doing a lot of crazy tilting then it could be the best option for an older truck. I would say carb swap to make your life easier for an old clunker.

Schurkey

The fuel induction system doesn't care how many bolts are holding the main caps to the block.
The fuel induction system doesn't care.
The fuel induction system doesn't care as long as the compression ratio is somewhere between 8.6:1 and 9:6:1, and you have proper squish/quench clearance. Farther outside that range may be acceptable, but I haven't tried it.
THAT the induction system will be affected by.
Again, if the compression is somewhere around 9.6:1 or thereabouts, AND you have proper squish/quench, I don't see a problem EXCEPT for the two middle intake manifold bolts on each side, which are going to require some manifold rework. (Or a different intake manifold.)
Can't say--it will depend on what's wrong with the TBI system including sensors and wire harness. May depend on how many PROMs you'll have to burn to get the tune correct.
First Guess: Driveability problems due to much "bigger" cam than the computer is programmed to deal with. The 268 cam is pretty mild by hot-rod standards, but it's got way more duration than the factory TBI cams.