Radley, Jack wrote:
>
> Back to the list with my Carb problems.
>
> Recap:
>
> I have a 76 TR6 with 8,000 original miles, I recently had my carbs rebuilt
> to cure very rough acceleration from a stop (car ran fine at cruising
> speed).
>
> After the rebuild, the car ran fine from a stop, but would run a little
> rough (very slight shudder or pulsating-pulling feeling and a little garble
> in the exhaust) at cruising speed, once warmed up, between 1500 and 2500
> RPM. Car runs great up to 1500 RPM and above 2500 RPM.
>
> At the suggestion of the list I replaced the rotor and distributor cap with
> no improvement.
>
> The car went back to the mechanic who diagnosed it as too rich a mixture
> when the carb is at maximum vacuum (at 1500-2500 RPM). He then adjusted the
> trimmer screw near the temperature compensator by turning it in a full turn.
> He commenting that there is a lot of adjustment left, so drive it and if it
> isn't better, come back and he'll adjust it more. Last night I decided that
> it would be better if I made the adjustments while I was test driving the
> car. I went in a half turn at a time and then back out a half turn at a
> time. I could not get the engine to run just right.
>
> My questions:
>
> What is the correct point to start from with the trimmer screw (since I
> probably want to go back to point A and see what happens)?
>
> Is the trimmer screw the correct thing to adjust for this problem?
>
> Shouldn't the mixture be adjusted through the top of the dashpot (or is a 76
> TR6 not adjustable)?
>
> Any other suggestions?
>
> Jack Radley
> 76TR6
Jack, according to the Haynes ZS Manual, this screw is an idle trim
screw which provides a fine adjustment to the idling mixture ratio to
compensate for the difference between a new engine that is 'tight' and
later when it is run-in. According to the Haynes a new engine may be
run on a comparitively weak mixture and as the engine is run in the
screw may be progressively turned in until it is fully seated. If I
read the Haynes correctly, this means that this adjustment does little
to the mixture above idle AND screwing it in makes the mixture richer
not leaner. And yes the correct place to adjust the mixture is the
screw at the bottom of the dashpot cylinder.
Hope this helps.
Skip Osmundsen
'76 TR6
'60 TR3A
|