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THE HEALEY ROCKER SHAFT (3000 Series)By Sam Guess (From the May 1975 Chatter) The Healey rocker shaft is located under the valve cover on top of the engine and can be a readily remedied source of trouble. The function of the rocker shaft is to hold the rockers
in place on the valve train and to keep the valve timing intact. Oil is fed
through the oil feed pipe into the shaft and along each rocker to oil the top of
the engine and return. There is tremendous pressure here and what may occur is
simply: Rockers turning on the shaft sometimes score it and the resulting gap
allows oil in be forced out of the rockers and through the breather pipes to the
rear carburetor. Therefore you are fouling your carburetors">
THE HEALEY ROCKER SHAFT (3000 By Sam
Guess (From the May 1975 Chatter) The Healey rocker shaft is located under
the valve cover on top of the engine and can be a readily remedied source of
trouble. The function of the rocker shaft is to hold the rockers
in place on the valve train and to keep the valve timing intact. Oil is fed
through the oil feed pipe into the shaft and along each rocker to oil the top of
the engine and return. There is tremendous pressure here and what may occur is
simply: Rockers turning on the shaft sometimes score it and the resulting gap
allows oil in be forced out of the rockers and through the breather pipes to the
rear carburetor. Therefore you are fouling your carburetors, mixing oil and gas
in the engine, apparently using an excess of oil which your local repair shop
will tell you is caused by everything but a rocker shaft. My rule (or mechanical
repair is simple. I will have no work performed on the car, except machining on
parts I bring in. Why? Simply because Healeys are my hobby and I have not found
anyone that can pinpoint and cure a problem better than I can. Money is the
mother of invention but more important is pride; the knowledge that you can do
it yourself. The shaft runs the length of the engine and holds
twelve rockers, the opposite ends of which sit on the valve stem and the push
rods. With the engine running, the rockers pivot up and down and in order
operate the intake and exhaust valves. Valve tinting is adjusted on each rocker
to spec and should be part of every major tune-up, which is rarely done when the
car is taken to an outside garage. A car can never be tuned properly without the valves
timed and adjusted properly! There is a simple test to determine if you have a
problem with your rocker shaft leaking oil. Inspect your air cleaners and if
they contain liquid oil, drain and reoil the mesh alter the next operation.
Remove the valve cover being careful not to break the gasket. Start she engine
and observe the oil being pushed out the top of each rocker arm. If it is more
than a trickle and is now coating the inside of your garage with oil you will
need to proceed further. The spurt of oil coming our of the rocker arms should
be only a trickle. Any more and you might have blowby from the rings or
bearings and replacement of the shaft will not solve the problem. Assuming that at this point you are now covered in oil
from the shaft, proceed! Remove the shaft per the factory manual. If you don’t
own a manual, GET ONE! Its more important in my opinion than the four wheels you
drive on! After the shaft is removed, proceed to dismantle the
rocket arms, springs, and columns. You can drift the rocker arms off
easily with a rubber mallet if they are tight. You now need a micrometer
and common sense here. If there are grooves where the arms pivot, the shaft will
have to be replaced. If there is no obvious wear or grooving as eyeballed mike
the areas where the arms fit. The minimum reading here is .8110 for the diameter
of the shaft with the bore of the arm at .909-. 910 (all measurements in
inches). If you are below the minimum proceed to
obtain a replacement part. In my case I bought two from parts car I came across
for under $30.00 with a guarantee of suitability or refund. Why used? Simply
because I couldn’t find a new one in this country and thus avoided the extra
machine shop work that is needed to ream out the bushings, drill them, and seal
the ends. I cleaned and disassembled each shaft and determined with the
micrometer that only one was above minimum spec. One was in worse condition than
the original. I next reassembled the shaft, reinstalled, and torque the nuts to
factory specs. Next I adjusted the valves with the rule of thirteen and the
starter solenoid button. Alter this I started the engine and
beheld only a trickle from the rocker arms. I put back the valve cover and the
rear carburetor and went for a hard drive. Not a drop of oil at the tee. Problem
solved for a cost of under 530 and three or four hour’s work. If you have to buy a replacement shaft and bushings,
your parts cost alone will run close to $100.00, the machine shop should be
under $20.00. |