By Bob Wilson
A. If your engine is not already disassembled, remove the valve covers.
B. You will need a breaker bar or a large 1/2 drive ratchet and socket to rotate your engine by hand via the bolt on the front of the crankshaft. This is much easier if the spark plugs are removed. Rotate the engine clockwise and watch the exhaust valve on the particular cylinder you want to adjust. If you’re unsure of which valve is the exhaust valve, look at your exhaust manifold or header, and the exhaust valve will line up with it. When the exhaust valve begins to open, stop and adjust that cylinder’s intake rocker arm. This is the point in the rotation of the camshaft where the intake valve is closed and the lifter is directly opposite of the cam lobe.
C. Loosen the retaining nut on the rocker arm to remove any tension from the pushrod. If the lifter is filled with oil, wait a minute or two for it to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. If you are installing new lifters, which are not oil filled, you don’t need to wait. You can start adjusting right away.
D. Gently rotate the intake pushrod with your fingers while tightening down the rocker arm retaining nut. When you first feel a slight resistance at the pushrod, you are just starting to compress the spring inside the lifter. Turn the retaining nut down one half to one full turn from this point. Lock the nut into position. The intake is now adjusted properly.
E. Hand turn the engine again, watching the intake valve that you just adjusted. It will open fully and then begin to close. When the intake valve is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. This is the spot where the exhaust valve is on the base circle of the cam. Adjust the exhaust rocker just like you did the intake.
F. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again. In summary, adjust the exhaust valve just as the intake is closes, and adjust the intake just as the exhaust valve is beginning to open.
1. When building a fresh engine, pre-adjust all the rockers to the point where there is no free play in the pushrods. Rotate the engine a few times while doing this so all the pushrods have no free play while on the base circle of the cam. You don’t want to adjust for free play while the cam is trying to open the valve corresponding to that particular rocker. This will give you a good starting point.
2. Many Fords used cylinder heads that had non-adjustable rockers in them. This was accomplished by using rocker studs that had a pronounced shoulder on them and a nut was just torqued into place, or in the case of six cylinder engines and FE style big blocks, a bolt down rocker arm shaft.. This is very simple for stock applications when the engine parts are all new, but not as good for rebuilds or performance applications. The studs are pressed into the heads instead of screwed in, and they will pull out easily with performance cams and stiff valve springs. Also, if you have to mill the heads when rebuilding them, you also need to change pushrods as the length requirements will change and the rockers are not adjustable. Most people rebuilding small block Fords will convert to screw-in rocker studs that are adjustable. Your factory shop manual should tell you which kind you have.
3. Hydraulic valve lifters are not nearly as fussy as solid lifters, and getting them close is usually good enough. Hydraulic lifters have a preload range that provides a margin of error.
4. Remember, when the exhaust valve begins to open, stop and adjust that cylinder’s intake rocker arm. When the intake valve is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. Remembering this simple procedure wil get you on your way.
By Bob Wilson