DIY_EFI Digest V4 #601

[William T Wilson]

On Mon, 25 Oct 1999, DIY_EFI Digest wrote:

> I have a friend who's trying to get a spec RX7 series running back
> home, and would like to have a "spec" rev limiter in the interest of

It is difficult to build an ignition based rev limiter for an RX-7 because
of the dual ignition system.

> reliability.  I'm not fully up on the ignition system but there are
> two distributors (with points), along with a set of leading and

There should be only one distributor on an RX-7.  Earlier Mazda cars had
two, but the RX-7 should have one that has two sets of points in it.

> trailing plugs.  My thought is to kill spark to one set of plugs (vs
> all of them) to prevent nasty back-fires, while hopefully cutting
> power.

Backfires (actually afterburn - fire in the exhaust) is okay.  Especially
in a racing series.  Scare your opponents, amaze your friends.

The bad news is that either ignition is enough on its own to ignite the
fuel and allow you to overrev the engine.  You have to cut both ignition
systems.  Anyway, why do you need a rev limiter?  The redline on the RX-7
is only there to give some color to the tachometer.  I have overrevved my
1st generation RX-7 all the way to 8500 RPM without damage.  (don't make a
habit of that. :} )