HEI

[Raymond C Drouillard]

If you have a GM seven-pin HEI module that is designed to work with a
computer, you can easily use it without the computer.  According to the
diagram available on the FTP site (and my own experience), it's simply a
matter of pulling the computer connecter.  There are four wires that go
to the computer.  One is a ground, one is a signal input, one is a signal
output, and one is a 5V emable signal from the computer.  If that fourth
pin doesn't have 5V (if it is left open), the computer pins will be
bypassed and the module will simply be a dumb ignition module - which is
exactly what you want.

Of course, you're still left with the task of setting up a centripital
and vacuum advance.  The distributer that I took apart had a solid
connection where the vacuum advance used to be.

Ray Drouillard


On Tue, 9 Jun 1998 15:42:40 -0400 "Donovan L. Dibble"
<ddibble at mail.eds.com> writes:
>
>The HEI connections for a non-computer are reasonably straightforward.
>The module has four pins (2 on each 'end').  Mine has two terminals
>labelled 'W' and 'G' and connect to the pickup coil.  (The wires going
to
>the coil are Green and White.  Thanks GM!)  The other two go to the coil
>and battery (Convienently labelled 'C' and 'B') and run up to the
distributor
>cap.  If you can get a service manual from a late 70's car, the
information 
>should be there.  I'm not sure if you can simply replace the module with
a
>non-computer type without changing the distributor since the connector
>isn't the same.  If your module is the same as mine (and if I remember
>correctly), there are 6 pins total.  The extra pins are for EST and
Bypass
>commands from the computer.  There is also a signal back to the ECM
>to send it the pickup coil signals.  I'd think a complete distributor
swap
>would be easiest to do.
>
>(Now a little background and personal info....)
>Currently, I'm working on making my own ESC/ECM system for a
>turbocharged '81 Trans Am.  My ESC box self destructed and,
unfortunately,
>GM doesn't make them anymore.  My first move was to replace the
>distributor/carb with older non-computer units and get the car running.
>(Can't live without T-tops in the summer!!)  Now I'm entertaining the
idea of
>constructing my own ESC/ TBI ECM with a PIC, 68HC11 and some hard work.
>The nice thing is that a majority of the sensors are already present
since
>the car came with the CCC system.  I don't have to find many sensors, 
>I justhave to find the time......
>
>Don
>
>In the event my information isn't completely correct on the HEI stuff, 
>
>please
>be gentle :)
>
>richard vandervoort wrote:
>>
>> Does anyone have a wiring diagram for internal wiring for a standard 
>
>vacuum and mechanical HEI.  I want to convert a 79 Caddy with an
electronic 
>spark retard (CA only) to eliminate this fried black box.  Thanks in
advance.
>
>Go to the library and look up most any V8 RWD GM car from the late 70s
>or early 80s.  I can say from experience that '78 Monte Carlos have
>vacuum/mechanical HEI with the internal coil.
>
>- --steve
>
>>
>> Free web-based email, Forever, From anywhere!
>> http://www.mailexcite.com
>
>- --
>Steve Ravet
>International Meta Systems
>http://www.imes.com
>steve at imes.com
>
>
>

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