If I put on a carb intake manifold with an adapter for TBI and used a 454 TBI unit with the 305 injectors would that hurt a stock programed 305 TBI engine?

 

Yep, the throttle plates now let in alot more air for a particular TPS reading. Your TPS enrichement will be way off.

Why do you want to go to a 454 TBI on a stock 305 anyway. It will pull, at MOST 1-2 in/hg or 5 KPA of vacuum on a stock engine. Most of that can be eliminated by Ultimate TBI mods and an open element. You will be good until you reach about 310+ FWHP with the stock sized TBI and ultimate TBI mods. Injectors upgraded accordingly. Stock sized 61 lb/hr 350 injectors would probably be closer to right on that 454 TBI on-top of a stock 305 combo.

If you go with a spacer that has a slot underneath the TBI, between the intake, then open up a slot in the plenum of the intake, the system will now act as if the TBI flows more. Did this with my performer RPM/Projection adapter combo. Almost no restriction on a 265 RWHP engine all the way to 6,000 RPM. It can pull air for both sides of the intake from both sides of the TBI. Does the same thing as putting a 1" open carb spacer under a carb on a dual plane manifold.

 

Reason I would do it is because I am in the process of building the faster engine per say but I am waiting for certain parts to finish. But I am bored lol I would like to do things I can go ahead and get out the way and since I drive that car I would like it to work.