I had something similar 2 years ago and it was the coil. As the coil got
hotter, the more the miss. As the coil kept "failing" the worse the miss.
Bob Danielson
1975 TR6 CF38503U
Running w/ Throttle Body Injection
http://tr6.danielsonfamily.org
-----Original Message-----
From: owner-6pack@Autox.Team.Net [mailto:owner-6pack@Autox.Team.Net] On
Behalf Of Navarrette, Vance
Sent: Monday, July 09, 2007 1:13 PM
To: 6 Pack list; Triumph List
Subject: [6pack] Colicky TR6. Prize for correct diagnosis.
Listers:
Just thought I would share my recent frustrations fixing a low speed
miss.
Since I brought the 6 out of storage, it has been very colicky.
At first I thought perhaps bad gas, then I thought it was just bitter about
not being driven all winter. Hey, don't laugh, I am sure you would all swear
your TR6 has its moods.
The symptom was a low speed miss when pulling away from a stop.
Sometimes it would miss once, sometimes it would miss twice, sometimes no
miss. This is not a bog, but a soft pop and the car will jerk sharply.
Adjusting the choke made no difference, and the problem would occur when
both warm or cold, although the problem got somewhat worse as the car warmed
up. The engine would rev just fine with no breakup or missing at the upper
RPMS. Battery voltage was about 14 volts, temperature in the middle of the
gauge, healthy oil pressure. Stock ignition (Lucas coil and points, no
Pertronix). No blue smoke, no white smoke at idle or any other time.
My TR6 has a 270 degree cam, 9.6:1 CR, stock exhaust, dual zeniths
with B1AR needles. Carbs have been rebuilt, compression in all 6 cylinders
is 145PSI +/- 5 PSI. K&N air cleaners in a stock filter housing. Manifold
heat is connected. 1974-1/2 car with EGR and all emissions systems
connected. Stock rockers, valve lash set at 0.015", idle at 900 RPM - with
what sounds like a very *slight* miss at idle. <- another clue!!
OK, those are the symptoms. Here are some additional clues so that
you hairy chested LBC drivers can test your diagnostic acumen. I say this
because I always love a challenge, and I might as well torment you all in
the name of camaraderie. =:-o
Here are some additional clues:
1. Fresh plugs made no difference (Champion 12NY).
2. Adjusting the mixture rich or lean made no difference.
3. Fresh gas made no difference.
4. New plug wires made no difference.
5. Checked the timing, spot on at 4 ATDC dynamic. No observable
spark scatter when revved.
6. Wider or narrower plug gaps made no difference (+/- 0.005").
7. Vacuum retard functioning correctly.
8. Topped off the dashpots with penrite oil, still no difference.
OK, listers. Do you think you know what I missed? Can you offer a
shrewd insight (or a least a derogatory comment) as to my utter failure as
an LBC mechanic? I know the answer, as the miss was resolved just this
weekend.
I am offering a prize for the correct diagnosis. The winner will
receive one "attaboy", redeemable with $2.00 for a cup of Starbucks coffee
and the glory of having his or her kung fu publicly acknowledged as the
best.
Post your guess to the list, Kastner wannabes!
Vance
Checked by AVG.
Version: 7.5.476 / Virus Database: 269.10.2/891 - Release Date: 7/8/2007
6:32 PM
|