GM HEI circa 1985 info needed

[mrvette]

just take a say 30 ohm resistor,  most any value and put it across the output in
place of the coil, and scope minitor the output, to see if it's working,   b-4
hooking up the coil.....or you cold do it audibly,  those coils make a nice
thunk when they fire on a bench setup.....GENE

Jason Weir wrote:
> 
> Stowe, Ted-SEA wrote:
> 
> > hi, I am working on building a mutant Lucas/gm distributor for my mg
> > tbi
> > project.
> >
> > I have a '85 tbi system from a sunbird, which uses a HEI distributor.
> >
> > I have the matching GM ignition module which would of gone into that
> > set-up.
> > and I have a Lucas distributor which uses a hall effect sensor, which
> > fits
> > into my block.
> >
> > my problem is that the Lucas sensor has a 3 wires coming out of it,
> > whereas
> > the gm hall effect sensor uses 2. the gm system looks pretty simple
> > actually. so I am trying to figure out why the pommys used 3 wires.
> > one
> > might be a ground ? or center tap ??
> >
> > I suppose I could hook it up on a bench with a coil and work on
> > combinations
> > until I zap myself.
> > but I don't want to blow the module nor the sensor in the distributor.
> > and
> > without the ECU attached I don't know if that would work anyway ??
> >
> > also I get the idea that the ECU controlled all of the timing, so I
> > would
> > just take out the mechanical advance in the distributor and lock down
> > the
> > top plate ??
> >
> > and would this module fire off an external coil ok, as opposed to the
> > built
> > in GM coil ?
> >
> > and I see that the gm module has a heat sink area, something I have to
> > work
> > on, how much heat did that module put out ?
> >
> > thanks for your always excellent advice.
> >
> > Ted Stowe
> 
> Ted,    I ran into all of the problems that you mentioned above when I
> did my Jeep TBI conversion.  My fixes are as follows
> 
> 1. My pickup had three wires, I used a DVOM to find the one that went to
> ground, it actually was tied to ground inside the distributor and then I
> just hooked up the other 2 in the configuration that gave me the most
> advance.... I am still playing with this to get correct pickup and
> rotor/cap alignment (see #2)
> 
> 2.  I removed the vacuum advance and then removed the springs and
> weights of the centrifugal advance I used lockwire to disable the
> centrifugal movement... Then I used epoxy to hold the top plate from
> moving... I got it a little bit retarded so when the pickup fires the
> rotor is not positioned exactly how I want it, but I have not had the
> time to get around to fixing it...
> 
> 3.  I used the HEI module with no heatsink and it would cut out
> periodically so I got a couple of CPU heatsinks with fans.. It just
> happens that CPU fans are 12V so I wired them up to switched power so
> they run when the ignition is on...
> 
> --
> Jason Weir
> 88 Wrangler - 258 Chevy TBI
> Fayetteville, North Carolina
> http://home.att.net/~jweir  --- Jeep Home Page
> mailto:jweir at att.net

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