EFI Conv.

[peter paul fenske]

Hi All

Well the subject of the throttle body conversions is rather interesting.

While I have been working with GM tpi recently and so far rather
successfully I have done some throttle body work.

There are 4 barrel to throttle body adapters available
commercially. I believe even GM lists one for the early 
454SS.

At swap meets have seen the whole throttle body setup for less than
200$ including all sensors and ECM.

There are some restrictions to it use which can be overcome.

First off a lowpressure? fuel pump must be used. 15 lbs is the nominal
pressure. Most EFI pumps are in the 50 lb range.

Gm pumps are available although usually tank mounted. I have converted these
to rail mnt but since they weren't designed for this I can't vouch for
their reliability in this mode. 

Also a VSS signal is required. I have used a taxi read switch which mounts
between the tranny speedo and speedo cable. This device costs in
the 50$ range.


Important too is the MAP signal. An engine with 16 inches of vacum would 
operate marginally with the system. Any less would be a catastrophy.

With the GM throttle body system in question Air flow is about 500 CFM
for a 5.7 derived system. A 454 SS throttle body is more but rare.

As for reprogramming the system I believe there was some folks on
this group that had reverse engineered a 91 GM ECM from a
gm truck. Maybe someone could look them up.

About the only info I have is the idle table location and the spark table.
I have not investigated the fueling.

Well hope that helps a bit.

GL all: peter