Dennis:
It can be many things, you will just need to work through the
possibilities.
Bad plug wires or perhaps a bad coil come to mind, as well as a vacuum leak. I
will assume that your tune-up covered all the bases such that valve lash,
dwell angle, damper oil, plug gap, timing, etc are up to snuff. I recommend
factory plug gap settings until you get this sorted. Are you sure your vacuum
lines are correctly configured? Vacuum retard, EGR valve, canister purge are
all routed correctly and leak free? Dizzy vacuum capsule working properly?
My personal favorite is what you already mentioned, a lean miss. If your
plugs are white, you are waaay lean. I am running a 270 degree cam, and I have
nice cardboard colored plugs using B1AR needles. I found the Jag needles to be
a bit on the rich side for my cam. Since your 285 degree cam is more radical,
the Jag needles may be fine. My recommendation is get your mixture
straightened out before doing anything else. THEN if you still have a miss,
try some of the other stuff.
Do not use the "lift the slide" method to set mixture - with your cam
this
won't work. Use plug cuts or a Color Tune instead.
Vance
Vance Navarrette
http://www.triumphowners.com/832
-----Original Message-----
From: 6pack-bounces@autox.team.net [mailto:6pack-bounces@autox.team.net] On
Behalf Of Dennis Culligan
<snip>
...the motor was bored .30 over, the head was milled to about 9:1
Compression and the cam was re-ground to specs similar to the 150HP
cam found in PI cars. The carbs and the exhaust system were left
bone stock. The car is equipped with a Pertronix ignition in the
dizzy and the dashpot oil is checked regularly.
After a break-in period, I noticed a slight stumble at 2000- 2500 rpm
under load (note that the motor idles fine (a little lumpy due to the cam)
and will run smoothly well up over 2500 pm while stationary).
<snip>
I'm considering moving back to the cooler spark plugs (my plugs are
almost white and I've NEVER had the "sandy colored" plugs that one is
supposed to have) and no amount of leaning or richening of the carbs
seems to make a positive difference.
<snip>
Dennis Culligan
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