[6pack] Left hand turn stutter

[Tomislav Marincic]

Andy,

All TR250's miss on left hand turns when the fuel gets somewhere below half
a tank. Fill it up and it'll go away.

The TR250 fuel tank (and perhaps 1969 TR6 twin-carb) did not contain the
internal baffles of the later models. When cornering to the left with less
than half a tank, the fuel sloshes to the right and the engine misses.

Why? We've beaten that to death in earlier threads with no resolution. (And
we may yet again) In theory, there's enough fuel in the float bowls that
the momentary surge shouldn't matter. Yet it happens.

Cheers, Tom
(Former CD3574L owner)

Message: 2
Date: Mon, 31 Aug 2009 12:35:44 -0700 (PDT)
From: Andrew Packard <apackard68 at att.net>
Subject: [6pack] Left hand turn stutter
To: 6pack at autox.team.net
Message-ID: <19322.65542.qm at web83813.mail.sp1.yahoo.com>
Content-Type: text/plain; charset="us-ascii"
 
Hello listers:
I completed the rebuild of my stock carb set up on Saturday
night, had a successful test drive that night, and then autocrossed
on Sunday. I gave the car a "B" for overall performance since it drove 90
miles each way to get to the event and it was 100 degrees or so the entire
afternoon in California's central valley. I have not yet rec'd my Stromberg
heat shield yet, so I ran without one. I shared my car with a fellow club
member and we each took 5 runs each that lasted about 70 seconds each. The
car did well the first two runs, but then began to hesitate around
hard left-hand corners for a couple runs and then was hesitating in only
mild
corners. I have an electric fuel pump putting out 6 psi that goes through a
regulator that reduces the flow to about 3 or 4 psi's. My float height is
about 16.75mm.
 
When I first attached the stock carbs off my storage shelf
before renewing the gaskets, the car ran okay with them but gushed out fuel
when the car was off with the fuel pump operating. During the rebuild, I
found the float height to be set too high at < 15mm. When it all went back
together, the new float heights prevented excess fuel flow. My inital
thought
is to remove the regulator and allow for the full 6 psi's to reach the
carbs,
keeping the fuel bowls full during fast runs. I also thought about raising
the float height a little to 16.25mm to help maintain higher fuel levels. My
other suspicion is that due to the heat from the weather, auto crossing and
my
headers without a heat shield, perhaps I was boiling the gas in the float
bowls. Could my timing also be contributing to a very hot engine bay? I
don't have the specs on the timing off hand.
 
Any opinions and thoughts are
welcome.
 
Andy Packard
CD6746