>From several queries over the past several days:
MGB CYLINDER HEADS: The earlier heads have a deeper combustion
chamber, the later ones a larger but shallower chamber, both of which are
the same size (about). The early heads have double springs (all 18G
engines) and the later heads have single springs (18V or 1972 and later).
The earlier heads have the oil port at the rear pedestal BETWEEN the 5/16
and 3/8 stud; the later heads (75 ->) the oil port is located IN FRONT of
those studs and uses a DIFFERENT pedestal. The early heads have no
provision for air injection into the exhaust; the later heads (68 ->) have
that provision. There were, during production, and available as a factory
supplied item, a "large valve head," but what size I do not know. The
Unipart supplied heads from England now often DO NOT have the provision for
the air injection. And just as a last note: The first valve to fail is
the #3 Exhaust, MGA -> MGB. Oh, and ALL MGA/MGB cylinder heads weep
between the head and block, just under the #2 and #3 plugs -- well, almost
all. Both these are design flaws. The second (weeping) can easily be
cured. Note that running a dual chain with a single sprung head is OK if
you use the short lifters; however, you should NOT run a single chain with
a dual spring head, especially with tall lifters.
l DRAINING THE FUEL TANK: Siphon what you can and pump the remainder
out with the fuel pump. If you are changing the sending unit, simply jack
up the car on the right side, allowing the fuel to slosh to the left.
ROCKER ARMS: Pressing in new bushings, honing those bushings, and
refacing the rockers is a machine shop job. All three of these tasks
should be performed at the same time, as honing the new bushings changes
the center of the rocker and the radiused face of the rocker MUST match.
Expect to pay $6-$8 each for this task.
B Ceeing you A-T Indy 96! John Twist
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