Re: TBI, was Re: Hornet status

["Jim Blair" <carnuck@xxxxxxxxxxx>]

A: Somehow in my collecting of things automotive, I ended up with an intake 
from a GM 2.5L with TBI, and one from a 3 cyl Geo with the injectors still 
on them. I have the Renix TBI system too, but it's going into my '84 
Cherokee.


From: Tom Jennings <tomj@xxxxxxx>
To: mail@xxxxxxxxxxxx
Subject: Re: TBI, was Re: Hornet status
Message-ID: <20050610094616.A1396@localhost>

On Fri, 10 Jun 2005, Sandwich Maker wrote:

> " I don't want to use knock sensors, crank-position sensors,
> " multi-coil or HEI ignition. I know all those things make for a
> " better system, but I don't have the time, money nor inclination.

> " *** All-GM OEM parts are the way to go. Cheap reliable and
> " plentiful!

> aren't these two statements somewhat at odds?  and swapping in a hei
> dist is easy, compared to everything else you're doing.


Since I have not ever run EFI, but only done paper research at
this point, I could be talking out my non-eating orfice.

I know it is possible to make a TBI system that is basically a
carburetor-replacement, that looks at only:

  * tailpipe O2 # cruising A/F; mileage
  * manifold pressure (vacuum) # engine demand/cruising
  * coolant temp # startup/temp compensation
  * throttle position # engine demand/cruising

That's what I want. I know more sensors mean more accurate maps,
and more control. I know that's better. I may eventually do all
that, but I don't want to start with it.

I also know systems. Every single component interacts with every
other component. Installation of part A interferes with existing
part B.  Connectors chosen, installed, repaired, mounted,
documented.  Tuning and experimentation.

For example, the Duraspark ignition I've worked out in
excruciating detail.  I'd rather not mess with it. I might want to
git HEI to it later, but I don't want to change multiple things at
one time.

The 1981 intake manual I'm using; it "just bolts onto the block",
but I have probably 50 hours in brackets, hoses, brake line
clearance, carb mounting, throttle linkage, trans linkage, etc to
make it actually work in this car.

So first I want to make a basic TBI system, one that I can trust.
Even without all the other inputs, it's got to beat a carburetor!



> i don't believe the chevy six ever had tbi, but if the ecm wants dist
> inputs wouldn't it be easier to mix 'n match gm parts than adapt to
> the duraspark?

Luckily, the middling ECMs have distrib outputs, not inputs, and
distributor spark control is open-loop, so it could probably be

safely ignored, and connected later. That sounds nice!