350-- Which Intake

[Michael Selig]

MS: A later model 350 manifold should work--If you are using the 305
injectors they are smaller than the corvette.  You could also be having a
fuel pump problem..

GM unit notes:

There have been many variations from 1985 to now,  so there is a problem
with
compatibility of parts.

The angle of the bolt holes in the intake manifolds vary if you are
considering picking up parts a yard.  85-86 manifolds angles same as rest,
bolt to older engines.  87-92 center hole drilled at unique angle.

Always get complete setup -- sensors, harness, computer, fuel pump and
manifold from the same donor car.
There are conflicts with Beltdrive accessories, exhaust plumbing, air
cleaner.
Stand alone wiring harnesses are available.

Injectors for the 305 rated at 19 lbs/hour
For 350 22 lbs/hour.
If using small units and adapting to a 350. install adjustable fuel pressure
regular in place if stock.  Need higher pressure for smaller injectors.

Fuel Lines:
Need to be plumbed for High pressure operation--uses flare nut fittings.
Need a low pressure return line that should be at least 2/3 tge size of the
feed.  A vent tube is also needed.
Corvette  fuel lines on the passenger side,  F cars on drivers side.

FUEL RAILS:
Lines that distribute fuel to all the injectors.
Fed by incoming fuel lines, pressurized by the fuel pump and pressure
adjusted by the regulator via the Manifold vacuum signal.
Connected also to the return line.

Fuel pump:
Most TPI systems use a min fuel pressure of 40-45 psi, so an electric fuel
pump is necessary.
Factory pumps are in the fuel tanks.  OE tanks have problematic baffling to
keep fuel from running away from the sump, during low fuel cornering.  If
the pump runs dry, the engine stumbles and stalls.
The fuel pump also keep cool in the tank.  When the pump runs dry it can
quickly kill itself.  Use an EFI tank with baffling or an external pump with
fuel reservoir.

PLENUM or upper manifold:
All have cast in Passenger EGRS
Pre 89s have another passage for cold start system--a triangular port
between the 2 throttle openings for the Idle Air Control Circuit.
All Plenums have a port for inlet air temp sensor and a power brake vacuum.
90-92 incorporate vacuum for the map sensor.

SIDE RUNNERS:
The big tubes that connect from Plenum to manifold.
Passenger sides are all the same.
Drivers side varies.  Pre 89 uses the auxiliary injector.
Street and Performance offers a plug kit to mate early runners with later
electronics.
Small tube feeds air to 9th injector--all drivers side units have it.
Smaller runners support higher rpm.

Throttle bodies:
Usually around 48 mm butterflies.
Pre 89 have a small triangular port on bottom which matches to the plenum to
receive air for the IAC.

Distributor:
Ignition systems must be compatible with EFI.
The ECU reads a signal from the distributor to determine injector firing
order.

What do you think?  Does anyone know anymore??  ms



Good judgment comes from experience, and a lotta that comes from bad
judgment.
"Reality will kill you unless you deal with it through myths and metaphors."
Ray Bradbury
Michael Selig, MD, FACC.
www.lifelinecardiology.com



----- Original Message -----
From: Shannen Durphey <shannen at grolen.com>
To: <diy_efi at efi332.eng.ohio-state.edu>
Sent: Sunday, April 18, 1999 5:40 PM
Subject: Re: Which Intake


Chris G. Lucas wrote:
>
> > I've looked at the GM TPI system, but since it was designed for a 305
> > ci, and runs out of breathing by 4500 RPM on a stock 305/350 small
> > block, I figure it's way too small for 434ci.  I've also considered
> > something like the Lingenfelter(sp)and the Accel TPI systems.  Most of
> > these are suppose to be good for 5,800 RPM on a 350 SBC, and I wonder if
> > they are big enough.  Are the bigger volumes in the after market systems
> > enough to feed a 434 engine in the low RPM range with the turbos pushing
> > enough air through the TPI system to run the engine up to 6,500 RPM?
> >
> > Is there another system out there that I should consider?
> >
> > Thanks for your help.
>
> Not that I know a dang thing about twin turbos, but I did run across a web
> site, (probably one everyone has already seen).  That has a twin turbo 305
> and tpi.  He has done alot of research and could probably give some ideas.
>  http://www.skulte.com/turbo.html
>
> Chris Lucas
Mr. Skulte was a member of this list for a while.  Search the archives
for his posts.
Shannen