CAROLINAS AUSTIN-HEALEY CLUB
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.
After 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 $30 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.