In a message dated 96-09-25 16:32:03 EDT, you write:
<< Last month, to pass (California) smog, I replaced the main jets and
leaned it out a little. After passing smog I enrichened the mixture
but I'm far from satisfied.
The symptoms? Popping on overrun, hunting on a steady throttle,
and coughing when cold. It accelerates fine, and idles well.
I dont see how changing the mains could do this, but maybe I
"bumped" something.
I'm not sure now how to proceed. The Haynes manual has precious
little. Should I:
- purchase a carb balancing tool?
- purchase the Bently manual?
- offer a human sacrifice to the Dark Lord Lucas?
Can anyone offer this poor soul (and others) a tutorial on the
mysteries of these "ancient" devices?
Shane Ingate and poppin' TR6 in San Diego >>
Shane,
It sounds like you've got a couple of problems all happening at once.
My first question is how, or why, did you change the "main jet" on a
Stromberg carb? Did you mean you changed the needles? If so did you replace
the needles with a thinner or thicker taper, and then lean them out?
The popping on over-run could be caused by a faulty deceleration by-pass
valve which provides a little extra air into the air/fuel mixture when the
throttle plate is closed and the engine, in over-run, is sucking more gas
than it needs (and back firing out the exhaust). There's a little diaphram in
the by-pass valve that drys out, hardens, and holes with age. They don't
usually come with the rebuild kits and I don't know if they're currently
available separately.
The hunting at crusing speed could be caused by a faulty EGR valve or system.
A vacuum leak, or sticking valve being open when it shouldn't, can result in
that kind of problem. If you're just running out of power at highway speeds,
you may want to change out your fuel filter and try it again.
The coughing when cold sounds like a choke (or maybe both) not opening,
forcing the car to run too lean at start-up. Has the car been doing this
since the rebuild, or has it just come on recently? If it just started
recently, check the action of the choke cables. Make sure they pull evenly on
both chokes and make sure one is not slipping in its trunion.
You'll need two special tools to work on those carbs. The UniSyn to balance
air flow is more accurate than a hose stuck in the ear. The mixture adjusting
tool is another worthwhile, and cheap, addition to your tool box - it's the
safest way to adjust mixture without fear of tearing the vacuum chamber
diaphram. Get the Haynes manual on Stromberg carbs for the most complete
information on those carbs.
And, I find, sacrificing an occasional squirrel helps. ;-)
Hope that helps,
Charlie B.
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