[DeTomaso] Grounding Circuit Recommendations

[Scott Couchman]

Doug, Thanks, great stuff! I can see I've still got more work to do, but I'm convinced I'm headed in the right direction. Scott

Doug Braun <doug at silicondesigns.com> wrote: Three grounds may be overkill but I found on my car that the stock ZF ground
strap is not adequate.  When I measured the voltage during cranking between
a
starter mounting bolt and the stud where the rear ground strap attaches to
the
ZF, I measured a large voltage drop of over 1V.  Cleaning the rear frame
ground
stud and the stud on the ZF where the ground strap attaches made no
difference.
By adding a second ground cable from the rear frame ground stud to one of
the
right side bell housing to engine block bolts, this same voltage drop was
reduced to 0.1 V and now the starter never fails to run fast, even when it's
hot.

My guess is that the aluminum case sections in the ZF have poor connections
between them due the natural oxide layer that readily grows on all aluminum
surfaces.  These thin oxide layers make for poor electrical connections.

Connecting to a bell housing bolt is nearly equivalent to connecting
directly
to a starter mounting bolt because of the massive 351C cast iron block
connecting them.

You can do your own voltage drop measurements with a simple voltmeter during
cranking by disconnecting the coil primary wires (so the engine will crank
but not start).  Connect the meter at the various connection points along
the
positive cable and solenoid and then the negative cable paths to the
starter.
This will show you where you are losing voltage while cranking so you know
where improvements may be needed.  It also requires two people, one to man
the voltmeter and one to work the ignition.

Doug Braun
blue 73L #5505

-----Original Message-----
From: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com]On Behalf Of MikeLDrew at aol.com
Sent: Wednesday, January 02, 2008 10:32 PM
To: scottcouchman at yahoo.com; detomaso at realbig.com
Subject: Re: [DeTomaso] Grounding Circuit Recommendations



In a message dated 12/29/07 6 26 43, scottcouchman at yahoo.com writes:


> Any suggestions or thoughts????
>

Besides the stock ground cables (one from the tail of the ZF to the chassis,
a second from the negative terminal of the battery to the main ground lug),
I
ran a third ground from the back of one cylinder head to the mounting bolt
for
the spreader bar, above the gearbox.

Three grounds is overkill.   Your proposal sounds ludicrous to me (but a LOT
of people know more about electricity than I do and I am more than happy to
be
corrected in my assessment by any of them!)

Mike





       
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