I've been having stumble, stuttering and general lack of power
above 3000 rpm for many months now. I've replaced the dist
with a non-smog, fuel pump, coil, resistor, fuel lines and filters
(main and banjo), adjusted the floats which were fine. Also the
battery because it was shot and was constantly pulling current
in. None of this has improved my situation much, and things
started to deteriorate to the point that the stumble occured
around 2000rpm, then 1500rpm. I've been off the freeways
for months now.
Things that have helped are:
Cleaning the SU vacuum domes and pistons with tons of
carb cleaner, soaking them to get all the oil and crud out.
Putting new damper oil in the dash pots, but carefully.
I used ATF. The big point here was not pouring directly
from the plastic oil bottle but using a syringe so that the
oil goes into the piston and not into the dome.
The Clymer manual says that oil in the dome is a cause
of much trouble.
So I'm back to stumble at 3000-3500.
In searching the internet I found one reference to SU
carbs that mentioned carefully centering the dome so
that the piston slides smoothly, by loosening the 4 screws
and using the piston lifter on the bottom to find the sweet
spot.
I'm not experienced enough and don't have the tools to
redo the jets or balance the carbs, but after that the
final resolution may be replacing the pistons because they
are no longer lifting straight, but binding against the side
and causing the stumble.
A Z therapy new carb would probably solve it straight away
though...
Cheers,
Tom.
Sunnyvale CA
'68 1600 Daily driver.
----- Original Message -----
From: "Eric Frisbee" <efris@qwest.net>
To: "snyler" <mtyler@hctc.net>; "noji" <noji-1@pacbell.net>;
<datsun-roadsters@autox.team.net>
Sent: Wednesday, February 26, 2003 6:38 PM
Subject: Re: stumble at 4000
> points/plugs/rotor/cap/wires/resistor block)
>
> So if it would run well for awhile, then not, where would be the likely
> place to start?
>
>
> You want to start someplace? I had the same stumble on my wifes '67...
> brand new points, condenser, ballast resister... brand new plugs, cap
and
> rotor too.
> That crappy running went away when I took a gamble and bought the first EI
> Distributor provided by Gary Boone... $200 is a small price to pay for
> NEVER having those stupid points in my car! Seems that they like to float
> at speed... oh say about 4000 rpm?? Do yourself a favor and spend the
> bucks... and donate those points to a worthy cause... like a museum!!!
>
> Just my $.02... :>)
>
> Eric
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