Chicagoland MG Club
Pulling a Cylinder Head
Obviously a broken valve spring requires immediate attention, but what about weak springs, especially after up-grading to a higher lift cam? The problem is in determining whether or not to pull the cylinder head.
If the head is not removed, an easy way to keep the valves from falling down into the cylinder is to snake in about three feet of small diameter rope into the cylinder while the piston is at BDC (Bottom Dead Center) of the cylinder and the valves you will be working on.
Rotate the crankshaft, clockwise towards TDC (Top Dead Center) BY HAND, via the crank pulley nut. DO NOT TRY TO TURN IT WITH THE STARTER. In fact, as in any other major repair, it's a good idea to have the battery disconnected to prevent accident or injury. Gradually rotate the crankshaft until light resistance is felt. The valves are held up by the compaction of the rope and no air pressure, coat hangers or trick tools are required!
After repair or replacement, don't forget to re-torque the head and set the valve clearance. On "A" and "B" series MG engines it's also a good idea to add a cooling system sealer to insure there are no leaks, since some of the cylinder head studs come up through the rocker pedestals and removing it MAY produce a leak. However, there is a 90% chance it will be OK after repair.
To remove a stubborn cylinder head try this first. Remove all cylinder head bolts but leave the spark plugs in place. Then crank the starter a few times-just tap it, don't turn it. The compression of the motor should break the gasket seal on the head.
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