distributor swap

Kenneth Keith auditude at gmail.com
Thu Mar 30 12:23:49 EST 2006

Well, it's not really a CIS vs. EFI thing either.  It's a knock
sensing thing.  So any turbo motor that has knock sensing, such as
MC(CIS), or any normally aspirated motor with knock sensing, such as
7A (EFI), will have a single window dizzy.  I don't know about the
high compression n/a 10v motors like NG (CIS), but I suspect they
would also have the single window wheel.  BUT those 10v distributors
are different from 20v dizzies in ways other than the number of
windows in the sheet metal cup for the hall sensor.

With the 5 window dizzy, the ECU can't control timing AFAIK.  Instead
it's done by vacuum advance (is it advance or retard?) on a Coupe GT,
for example.  The cars with the single window dizzy use the window in
combination with the flywheel teeth and timing pin to determine engine
position and adjust timing.

I hear that the n/a 7A motor has only two maps, we can call them "good
gas" and "bad gas."  I believe the 3B has a more sophisticated setup
where it can step down the timing and boost more gradually than in
just two steps.


"Rich Letsinger" <rletsinger at gmail.com> wrote:
> Yikes, I'm wrong. Sorry. I went back to my source and asked a few more
> questions. He'd modified a 7A distributor to have 5 windows by
> mixing-n-matching parts out of a 10v 80q distributor. Apparently it's the
> CIS cars that had a 5 window distributor. BTW, he said it was not easy.
> Again, sorry for the mis-information.
> Rich
> On 3/29/06, Kenneth Keith <auditude at gmail.com> wrote:
> >
> > Actually, that's incorrect.  7A's have knock sensing ignition too, and
> > therefore use a single window hall sensor setup.
> >
> > Ken
> >
> > "Rich Letsinger" <rletsinger at gmail.com>
> > >
> > > The 7A uses a 5 window hall sensor while the 3B has a 1 window.  They
> > are
> > > not interchangable.
> > >
> > > Rich
> > >
> > > On 3/28/06, lynnreid at valornet.com <lynnreid at valornet.com> wrote:
> > > >
> > > > Does anyone know if a distributor from a 3B engine can be  be used in
> > a 7a
> > > > engine?
> > > > Thanks
> > > > Les

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