Well,
I switched the brake wires and the coil wires...and evrything
is hunkey dorey in terms of a working tach and a working break pressure
tester switch (duh!).
However, the idle problemo did not disapear. Because of the apparent fitness
of the electrical system, by elimination I turned to the fuel system.
I installed a clear fuel filter right by the air cleaner....did a delivery check
and it was pumping fuel like no tomorrow!
I turned to the carbs. I douvble checked the timing with the vacuum off,
then stuck the vacuum back on and it advanced ALOT, like up to 20 deg....!
and was revving at 2000rpm. Obviously the vacuum advance system was working!
I took off the cleaners once again....and set
about cleaning the piston/suction pot assembly. I cleaned each on and
reassembled in turn. I tested the piston drop rate and the front carb dropped
a lot faster than the back...I had noticed this before but chosen to
ignore it (probably my first mistake). I had the jets flush, then winded them
down 12 flats a piece. I started her up after loosening all the
choke/accelleraor stuff. After undersoing the idle nuts ALL THE WAY I couldn't
get it to
idle under 2000rpm...weird. I then squatted doiwn and looked at the throats
at the same time...the front carb piston was lifted by almost 1/4!!
I could push it down with my fingers and the car would idle at a much lower
rpm, I let go...it shot straight back up!
I checked the oil in both dampers...all there...the front carb (the 1/4 in one)
has a tendency to squirt oil out of the hole in the top of the plastic damper
thingy. I tried to play with diffrent levels of oil in the back damper
so at least the fall rates would be the same. I managed this...but the
response of the front carb piston was much faster than the back carb...
Now, I know racers use heavy oil to prevent the piston rising too
quickly...this allows a slightly richer mixture on accelleration...ie more
power.
My hypothesis therefore is that the front carb is screwy
1) it would rest at 3/16in above the jet even at idle because it was worn
which is linked to poor oil damping...i.e. i could push it up and down
with my finger for 1/4 in withoiut feeling resistance!!
2) oil damping was non existent causing a weak mixture when I jabbed my foot
down...(which makes the piston rise fast with no damping) cured by pulling the
choke to richen the mixture
3) Generally crappy carb tuning because the carbs are so worn and out of wack.
I tried to remedy the different falling/rising rates by polishing the
the pistons...but to no avail. The piston wouldn't 'stay down' and I could
screw the idle screw all the way out and it wouldn't go below 2000rpm. i
played with the mixture....but this is no way to alter the idle!!!
How could I tune the car before??? Well, when I opened the pistons...the
front one was filthy...it looked like it had been jamming in two positions...
i.e., open or closed!! I never really compared the pistons before...
bad mistake! I wondered a few weeks ago why I couldn't balance the carbs
using the flow meter!!!!
I guess the true test of this will be if a different set of carbs will
work...we shall see.
Does it sound like the rear carby is ok...there is a fare bit of resistance to
pushing the piston up by hand...but it move smoothly. Also it passes the '5
second drop test'; recomended by Haynes. The front one is definately a gonner
though.
Any aggreements on this? The only thing I wonder about is why it would run
smothly now and again...piston decides to work...then sticks..then works..
and so on.
Marcus
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