Alright, I'm reviving this old thread for an update so as to avoid having to reitterate the long process that has led up to this point. But I have had another breakthrough that confirmed that I was battling another issue and is now resolved. So, I finally got around to installing a Holley TBI unit that I scored for nearly nothing ($40) a while back that was meant for a 4.3 S/T truck. There are only a couple minor and unimportant differences between this unit and one intended for a 5.7 or an F body. The throttle bores are still 2" 454 size bores that Holley rates at 670cfm. This unit is new enough to use the smaller Delphi bottom feed injectors that are capable of operating properly in low and high pressure systems ranging from a 12psi TBI system to a max of ~70psi. The main difference in this unit and one meant for a 5.7 V8 are the injectors are smaller for the smaller engine which are actually better suited for my odd setup. I got the TBI unit installed and everything adjusted and then set the fuel pressure to 21psi. That is the lowest pressure that I can run at idle without the regulator staying open and the pressure dropping drastically when you snap the throttle. Ahyhow, these injectors are rated at 72pph @ 21psi which is a bit big for my engine, but still less than the original injectors at these pressures. So, I updated the injector flow rate and the latency settings in the bin and burned a new memcal and took it for a test run. My first impression was that the car is a beast compared to how it drove with the original throttle body. I liked having the bigger throttle bores as I know that even the stock vortec bottom end could handle way more flow than the dinky 5.0/5.7 throttle bodies can provide. But with the stock pathetic exhaust manifolds from the original 305 still on the car I didn't expect the larger throttle body to make much, if any, of a difference. This was especially because it still made that "4 barrel sound" under heavy throttle that typically indicates that the engine can't use that much flow because either the cam is too small or the exhaust is too restricted. Back on track though, not only could the engine use the extra air, but it likes it a lot. Don't get me wrong, I have driven several 500hp+ cars including late model Corvette Z06's and even a 638hp ZR1 once. So, I'm under no impression that I have a monster by any means, but the difference was dramatic especially given that the car already ran pretty well after getting the fueling a little better under control.

Now, as for the relevant information regarding the breakthrough I've had. I had been told and then became very suspicious that TBI injectors behave very erratic and unpredictable when used at high fuel pressures such as the 30psi I was running. After having gotten the tuning under control and being able to make small adjustments and then check the results I began to notice that the fueling was still a little too inconsistent. Now that I have changed the throttle body and am using different injectors I can see just how erratic the old injectors had become. I know that the better flowing throttle body should have a little bit of an effect on the VE tables, but the ones I have been tweaking for months are now WAY off with the new unit. I am quite positive that it is because the old injectors were not performing in a consistent manner at all. After going back and looking at some O.E. VE tables and some of my older ones there is a natural curve to them all. In my latest VE tables, they are MUCH flatter. I believe that this is because with the original injectors once the fuel pressure is increased past a certain point the fuel delivery isn't as linear as you would expect. I know that I have seen data before showing just that and that is what I am basing my hypothesis on after seeing the big difference with the new injectors. The important fact in all this is that I now seem to have consistent hardware to work with that will allow me to finally work out the majority of the bugs that have plagued me since swapping engines. The last bit of work that I have left now is to replace my lifters that I believe to be causing a few funny quirks. I've had a set sitting in the basement that I began to recondition months ago that got moved to the bottom of the list as other work rolled in. But, I believe that I should be able to get back to them soon and hopefully get them installed sometime this winter.