--- In Cadillac_Performance_Association@yahoogroups.com
<j6gunz@y...>" <j6gunz@y...> wrote:
> Do you have any experiance with the factory EFI on the '75 500?
> I was wondering how capable this system is in handling compression,
> camshaft or valve changes?
> The engine will be used in a 4X4 application. Reliability, economy
> and torque are the priorities.
> Thank you
I am currently collecting parts for this EFI setup but I can say
this. I have the same EFI setup on my olds 350 motor. The motor is
mostly stock with exception of a mild cam. The system uses three
sensors to operate, a TPS, air temp, and water temp. There is no O2
sensor. There is a fast idle "thermal" switch to idle the engine
down after warm up. There is also another solinode that allows more
air to flow and increase engine idle when the air conditioning and
polution equipment is in use. The TPS works off of sequential
electrical contacts, not resistance like newer systems. While others
back in the day complained of problems with this analog efi system, I
am very please with it. Injector size, 2 ohms, on my 350 is 40.6
lb/hr. I believe the 500 injectors at 70 ish lb/hr. Keep in mind
with this being an analog setup the injectors sizes are usually twice
of that you might find on more modern systems. The injectors are
triggered in banks by two magnetic reed switches in the base of the
distributor. One thing you could do to alter the richness of the
system is add or replace the temp sensors with different resistance
values. Lower resistance, simulating a colder engine, more fuel.
This generally isn;t a problem if the final resitance values are
within reason. I have done this myself and it is fine for minor
differences in amounts of fuel injected. As in any EFI, you can
always increase the fuel pressure to get more fuel. As long as you
don't drastically change the power curve I would think you would be
fine with one of these systems. Hope this helps,