Conversion to EFI : Fuel system

[Mitch]

Folks,

I have decided, after recently installing a ZZ4 in my 66 El Camino, that I
have purchased my last carburetor; I'm going to EFI.  To that end I
recently purchased a 91 Camaro with 305 TBI and five speed as a daily
driver and to acquaint myself with EFI.  I am thinking of purchasing the
same engine and transmission combination (pre-93) from a local salvage yard
specializing in Camaros and installing it in a 66 Malibu I have which will
serve as a mule for EFI work.  I reckon it's a lot easier to install this
combination in a car designed for Chevy small blocks than to attempt
something weird like the Jaguar XJ6 Series I or 240Z (which is what I have
planned for later) swap first time.  I learn by doing and don't mind
working through a few projects to get to what I want eventually.

Anyway, after reading Mike Knell's books, as well as Hartman's, I have
decided the most challenging aspect of the swaps, for me, will be
retro-fitting the fuel systems on mechnical pump cars.  Instead of getting
custom-made fuel tanks, I'd like to implement the dual-pump external fuel
reservoir system described in Knell's TBI/TPI book.

I am working this out step by step.  To discuss this with you folks and
some other buddies, I have put some drawings up at:

	http://www.employees.org/~ozyman/carstuff/efi_fuel.htm

There are a number of vexing issues.

1. Where should the main return line go?  Knell's book suggests back to the
remote fuel reservoir, but I was concerned about heat.  I was thinking that
it would be best to return the fuel that has been to the intake manifold
back to the large tank.  If you return it to the small tank, some of it
goes back to the manifold for further heating.  If you return it to the
large tank, there is no such problem.

Now, my guess is it doesn't hurt to do it this way, but I was wondering
what the logic is for returning back to the remote reservoir.  I asked
Knell about this, and he said if you don't return to the reservoir you can
suck air if you run out of fuel from the main tank.  But if you run out of
fuel you run out of fuel; returning to the remote reservoir will maybe give
you another minute or so of life.

2. What is the air pressure in the main fuel tank?  Is it positive or
negative?  I am concerned because I thought the charcoal canister works
with positive air pressure in the fuel tank, and I don't see how it can be
positive in my diagram.  I have been assured from several quarters it is
about 1-2psi positive, but was looking for an exlpanation of this, since
you are always sucking fuel out of the tank.

3. Does it matter whether the pumps are above or below the fuel tank?  I
was assuming it didn't, but I recently read a book which suggested the
pumps should be below the tank.  This would be difficult for me to set up
in my car.

4. Just some general stuff: I am concerned about noise.  One idea I had was
to make this an assembly and mount it on rubber mounts, like motor mounts.
I was definitely considering some kind of case or cabinet (steel (like an
old toolbox) or plastic), but I am concerned about the hazard of buildup of
fumes, and also cooling for the pumps.  I'd need some way to vent the
thing.  I wonder whether it would be overkill to build some cooling/venting
fans into the cabinet.

So if you folks have any advice or ideas on this, please let me know.  I'll
continue to refine the diagrams as I nail this down.  After fooling around
with the stock TBI Malibu, I expect to convert the 327 in my garage to TBI
or port injection the diy_efi way.

Cheers,

Mitch Barrie
Goat Hill, CA