[6pack] Got a problem with the race car, need advice

[Navarrette, Vance]

	Chuck:

	I am going to assume that your tach is electric rather than mechanical. The
reason this is important is that if it is mechanical, the tach has nothing to
do with your ignition issues. If you have replaced the stock tach with an
electric one, it is giving you an important clue as to what is happening with
the ignition. I must also state that I do not run a Pertronix, so I am merely
speculating and asking questions. I am not speaking from experience so forgive
me if I state the obvious or say something ridiculous.
	I believe that the Pertronix is magnetically triggered, so I must ask if you
have checked the gap between the magnetic pick up and the magnets inside the
dizzy. I do not know if it is adjustable, but if it is, then it sounds as
though your pickup is not getting a clean signal from the little whirling
magnets so check the gap.
	Does your dizzy have a vacuum advance? If so, it it sticking? You said the
breakup occurs at WOT, which is when the vacuum advance should be disabled. If
it is sticking, it may be hanging on longer than it should so you run with too
much advance. Any indication of pinging (audible)? Are there any little bits
of aluminum on your spark plug electrodes (non-audible. Very destructive.).
	I think the Pertronix uses replaceable advance limiters, yes? Have they come
loose? Both advance springs still attached correctly? How much total advance
have you tailored the dizzy for? You should run no more than 34 to 36 degrees
of total advance (static timing plus mechanical advance). Vacuum advance would
be in addition to the mechanical advance.
	For racing, if you have vacuum advance try disconnecting it completely.
Vacuum advance is only for economy, and really does nothing for performance.
So try no vacuum advance just to eliminate that as a source of problems.

	just my $0.02

	Vance

    Vance Navarrette
    Knowledge is power.
    Power corrupts.
    Study hard, be evil.
    http://www.triumphowners.com/832

-----Original Message-----
From: Chuck Arnold and/or Kathleen Kelley
Sent: Monday, March 22, 2010 10:35 AM
Subject: [6pack] Got a problem with the race car, need advice

I have a petrol injected TR6 race car.  It has a Pertronix distributor
[the whole distributor, not just the points replacement in a stock
dizzy].  I also have a Crane ignition.

<snip>

The third session was longer, and over
the course of it the car started to cut out under WOT at about 4500 to
5500 RPM.  It did not do this always, but most of the time.  The tach
would swing wildly.  It felt a little like a rev limiter [which is
setto 7000 RPM],but only for an instant.  I did some investigating and
found that I did not have the distributor fully locked, and it had
"walked" to quite far advanced.  I though putting it back to where it
belonged would fix the issue.  It did not.  At the Sunday event it
just got worse, so I only got one long session in.


<snip>

Chuck