Using TBI on moded 5.7

[Walter Sherwin]

Yup, I agree with raising the TBI injectors to make the spray cone miss the
blades, even with a stock GM 2" dual TBI.   You will have to grind away some
of the throttle body casting material in order to raise the fuel injector
pod sufficiently (the fuel fittings will hit a portion of the casting near
the back).   About  0.25" works well.

GM introduced a bandaid "sort-of" fix for this same problem in the 93-95+
production 454's.  In some of the TBI manifolds they installed a drop tube
down the shorter of the two plenums.  The drop tube contained a small sheet
metal deflector which would supposedly "unpaddle" the fuel away from the
rear cylinders toward the front cylinders.

Raising the injectors helps "both" plenums, and works more effectively than
the paddle.  Increased fuel pressure also has a slight effect upon the cone
angle (wider) and strength of the spray, which helps a small amount.

Walt.

PS:  Grumpy, have not forgot about the increased pressure constant/EGR mass
message.  I just type really slow........






>  Also, if you machine for bigger butterflies, you'll need to do the above
>to set the spacing for the injectors.  When you install the larger
>butterflies the "cone" winds up totally on the buterfly instead of at the
>"air gap" where the butterfly is closest to the throttle bore.  Going from
>1.8s to 2.0 took raising the injectors about 1/8" inch...
>Grumpy
>    Was getting to want to almost bypass the Smokey Ram, and go TPI, but
this
>SR, 730, and high pressure injectors is starting to sound really
>good/different...