Depends on the tach.  The basic idea is sound but tachs have widely varying
requirements for drive.  The divide  by three will give the correct rate but
what are the duty cycle and pulse voltage requirements?  Tach makers are
absurdly stingy with this kind of info.

Tracy

----- Original Message -----
From: "Haywire" <haywire@telus.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, July 27, 2003 3:21 PM
Subject: [FlyRotary] Re: Tachs & things


> Hi Dave;
> Thanks for the info, but I already have my wires. It wasn't really a big
> deal, I was just pointing out that the whole GM-LS1 package is not as
> "off-the-shelf" as expected. And that it is not a simple matter to swap
> wires from my Jeep, to test operation of an inductive tach.
> I had ordered 2 divide-by-"N" binary counters from a local dealer for
$1.05
> each, but he informed me that they might be up to 2 weeks, so I found a
> different divide-by-"N" counter on Digi-Key for $0.71, but I ordered 25 of
> 'em. Should be here in 2 days. Hopefully it will work on the tach.
> Tracy, if you're listening, what do you think of this idea to divide the
12
> pulse EC2 tach pulse by 3 to give a signal that will indicate correctly on
a
> 4-stroke tach set for 8 cylinders?
>
> S. Todd Bartrim
> Turbo 13B RV-9Endurance
> C-FSTB
> http://www3.telus.net/haywire/RV-9/C-FSTB.htm
>
>    "Whatever you vividly imagine, Ardently desire, Sincerely believe in,
> Enthusiastically act upon, Must inevitably come to pass".
>
> > -----Original Message-----
> > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On
> > Behalf Of David Leonard
> > Sent: Sunday, July 27, 2003 10:57 AM
> > To: Rotary motors in aircraft
> > Subject: [FlyRotary] Re: Tachs & things
> >
> >
> > Todd,
> > I found getting wires for the GM coils very easy.  Simply order a set of
> > MSD custom wires then call MSD for the fittings.(got mine from Summit)
> > They will send them free in a few days.  Here is the original message
> > from Al....
> >
> >
> >   "Looks basically the same idea as the MSD 8.5mm wires.  Best price I
> > found on the MSD wires was at www.sdpc2000.com .
> >
> > "Since the only sets that MSD makes with the LS1 coils end sockets are
> > factory made for specific engines, I talked directly to the MSD tech rep
> > and he offered to send the LS1 ends at no charge, so I could put them on
> > a "universal" set from a retailer.  If you are going this route, call
> > MSD at 915-855-7123 and them you need the LS1 coil ends for your
> > wires.-Al Gietzen"
> >
> > David Leonard
> > The Rotary Roster:
> > http://members.aol.com/_ht_a/rotaryroster/index.html
> >
> > > -----Original Message-----
> > > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
> > On
> > > Behalf Of Haywire
> > > Sent: Sunday, July 27, 2003 3:38 AM
> > > To: Rotary motors in aircraft
> > > Subject: [FlyRotary] Re: Tachs & things
> > >
> > >
> > > Hi Ernest;
> > >
> > >
> > > > Todd,
> > > >   What kind of plug wires are you running there?
> > >
> > > They are a custom made plug as the GM 'vette coils don't fit a
> > standard
> > > plug
> > > wire. I seem to remember the parts guy saying that all the plug wires
> > are
> > > suppression these days, however there is no marking on the wires to
> > > confirm
> > > this.
> > > Anybody who is yet to order the EC2 should know this when
> > deciding
> > > whether
> > > to have it set up for Mazda coils or GM coils. When I made my choice I
> > > assumed it would be a no-brainer. Knowing that the Mazda coils are
> > > expensive
> > > and assuming they may be hard to find, I figured that the GM coils
> > would
> > > be
> > > a cheap off-the-shelf product, available from any number of
> > aftermarket
> > > parts stores. They are anything but. This is not to say that they
> > won't
> > > work
> > > well, but just a heads up, that they are not as easy & cheap to use as
> > > might
> > > be expected.
> > >
> > >
> > > >
> > > > So, with this theory:  Your timing light might be working because
> > it's
> > > > pickup is more sensitive.  That could be because it has more wraps
> > of
> > > > wire in it's coil, or because it has a more expensive transistor.
> > Or
> > > > it could have a Hall Effect transistory and the tach not.  But it's
> > all
> > > > to say that you're not emitting enough noise for the tachs, even
> > though
> > > > there is enough for the timing light.
> > >
> > > A quick inspection of the inductive pick-ups on both instruments
> > revealed
> > > that the timing light has far more wraps of a much finer wire than on
> > the
> > > tach.
> > >
> > > >
> > > > Try using an unshielded wire on one plug that you attach the tach to
> > and
> > > > see if you get any response.  If the tach works on your car, try
> > pulling
> > > > one wire from there for just a few minutes as a cheap test.
> > >
> > > Good idea, but as pointed out above, the standard plug wires won't fit
> > on
> > > the GM coils :-(. Now with that said, I must confess that I haven't
> > even
> > > tried a standard plug wire. When I bought the coils and asked for
> > wires, I
> > > was informed that they wouldn't have anything to fit them, but they
> > were
> > > able to have some made up and shipped up next day at no extra cost.
> > > This is the unfortunate thing about having the airplane at the
> > > airport.
> > > It's not as easy to quickly try new things, when good suggestions come
> > in.
> > >
> > > S. Todd Bartrim
> > > Turbo 13B RV-9Endurance
> > > C-FSTB
> > > http://www3.telus.net/haywire/RV-9/C-FSTB.htm
> > >
> > >    "Whatever you vividly imagine, Ardently desire, Sincerely believe
> > in,
> > > Enthusiastically act upon, Must inevitably come to pass".
> > >
> > >
> > > >>  Homepage:  http://www.flyrotary.com/
> > > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >
> >
> > >>  Homepage:  http://www.flyrotary.com/
> > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>
>
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