Charles,
Try reaching under the carbs and tapping on the bottom of the jet to
move it upwards, sometimes when the choke is used the jet will stick
in the down position, usually on rebuilt carbs.
It's worth a look, Brad
----- Original Message -----
From "Charles Sorkin" <cdsorkin at ix.netcom.com>
To: "Spridgets List" <spridgets@autox.team.net>
Sent: Saturday, August 12, 2000 3:22 PM
Subject: Tune-up + exhaust fix = Backfiring
What an irritiating afternoon... first the rain prevents any quality
driving time, so I decide to do some periodic maintenance on the
Midget.
Change the transmission oil, fuel filter, set-up the carbs, and fix a
minor
exhaust leak at the manifold-to-pipe joint. I adjusted the carbs for
both
mixture and air-flow, and they seemed to be pretty good, though I was
surprised that the jets were backed out significantly further than I
thought
they should be. (I started at 15 flats out.) I wasn't getting any
smoke,
and when raising the piston slightly, I got a momentary increase in
RPMs,
just like the book says.
Then I tried to fix the exhaust leak, including a new gasket and
studs. I
found that I could not use two of the studs because of rust and
stripping on
the manifold flange, but the previous bolts were loose anyway, so I
figured
that I would temporarily just clamp the pipe with some threaded rod
until I
could replace the manifold or get a header. (Grrr.....)
Now for the surprise. I restart the car, and it runs terribly. First
there
was lots of backfiring, which would indicate that my exhaust leak has
gotten
worse. (But that doesn't make sense, since I clamped it down pretty
well.
But now I'm getting all kinds of dark smoke, particularly during a
backfire.
And the engine runs extremely roughly. The only change I made to the
carburetor since setting it was to replace the throttle and choke
springs.
I know that fixing the leak would change RPMs due to eliminating the
unusual
back pressure, but why should that affect the mixture?
What could be the problem? When jets wear out, how do they fail?
And as for the decision between performance header and stock manifold,
money
aside, what do folks recommend? Which is easier to install? On the
header,
where does the outlet connect to the pipe... under the carbs or lower
down?
Is there the proper size exhaust pipe available "off-the-shelf?"
Worst of all, I'm out of Old Speckled Hen.
Regards,
Charles
'74 Midget
'68 Sprite
Bloomfield, NJ
cdsorkin@ix.netcom.com
"How about we duck inside for a Hen?"
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