Bill,
The O-ring you need to replace is in the piston/damper assembly. It is very
easy to replace:
1)Remove the piston assembly from the car.
2)Use a small flathead screwdriver to fully remove the screw towards the
bottom of the piston.
3)Use your trusty "Z-S needle adjustment wrench" (or long 4 mm allen wrench[I
think]) and count the number of turns it takes to enrich the needle
completely until it seats (clockwise).
4)Then completely remove the needle buy turning the wrench counterclockwise.
5)Use the flat side of a suitably sized drill bit or a drift through the
bottom of the piston and gingerly knock out the star lockwasher and
adjustment screw.
6)The O-ring is in the adjustment screw. Usually easier to cut it off with a
sharp razor blade-sometimes it just falls off.
7)Place the adjustment bolt and star lockwasher on the top of the assembly
and drift them back into place until the seat.
8)Replace the needle and tighten the nut all the way, then count back the
number of turns you counted in #3.
9)Replace the lock screw and adjust tightness.
10) Replace entire piston assembly
11)Your done!
I worked at a British Car parts shop for two years and rebuilt a number of
CD-175 and CD-150 carbs and they really are pretty easy to understand once
you delve into them.
Good luck!
Steve Sanchez
1977 MGB currently with dual SU HIF's, but getting a "breath freshioner" this
week of smog purposes!
PS If your carb has the brass plug in the bottom of the float chamber, DON'T
MESS WITH IT! That plug was used on another carb by BL to adjust a different
jet set up (much like an SU). If you are replacing the O-ring in the piston,
you should also replace the O-ring in that plug because if it drips, it will
drip right on the catalytic converter or the cover over it. You will need to
remove the carb, drain all the fuel out of the float bowl, remove the float
bowl, and gently press the plastic tabs in and remove the plug (don't pry on
the plug from the bottom of the float chamber). Be very careful with the
plastic tabs b/c they have been submersed in fuel for 20+ years! Replace the
O-ring, and motor on!
|