He's definitely going to be flowing more air thru the motor with all the mods planned. If you use 4.3 injectors with 2.8 TBI on a bone-stock 2.8 it'll run terribly rich. But maybe not so bad with a breathed-upon motor.

The Holley Big-Bore TBI I had on my old hot-rodded 2.8 worked fine. It did feel a tad 'over-carbureted' but not to a drastic degree. The airflow improvements were more noticable at the midrange-to-upper end.

The ECM should be able to meter OK with the larger injectors when in Closed Loop. However with a modded motor, fuel demand on cold starts is quite a bit higher and you can experience lean-surge until Closed Loop. The problem you have with a 3.4 conversion. Larger injectors or increased fuel pressure usually eliminates this problem. Again, the tendency to do this will most likely be less exagerrated using the smaller-bored TBI.

I experienced cold-start lean surging with my 3.1 buildup, had to break the spot weld on the adjustment collar of the stock 2.8 TBI and jack the fuel pressure up. Doesn't surge now and runs a lot better in Closed Loop, too.

Anyway, if it does run too rich with the 4.3 injectors he can always put the 2.8 ones back in. Lots of room to play with, you can use one set of injectors or the other and adjust fuel pressure to suit.

BTW, I wasn't paying close enough attention to the K&N discussion <img src="/forums/images/graemlins/sleeping.gif" alt="" /> My K&N is not the cone filter for a cold-air setup, but the standard drop-in replacement. To get more air in the stock air cleaner and not make a lot of noise, I spliced in another snorkel, chopped from an old S-10 air cleaner. The new snorkel has the hot-air-inlet side blocked off, and the stove tee'd into the stock heat stove vacuum line, such that after the engine warms up, both snorkels open. Makes a big diff in airflow and virtually as quiet as stock. Lots better than a flipped lid!