Recently, i've been hearing a tapping sound from my engine. I believe the cause to be loose rocker arms. I was preparing to tighten them, however i ran into a few issues. The engine is a '68 289. The heads have been replaced, i believe they are from a later mustang but i do not know for sure. All the manuals and websites tell me that the proper way to set valve lash for a '68 289 is to go to zero lash, then a 1/4 turn. I was planning on doing this before i noticed that i have the adjustable setup and require the use of a feeler gauge to set valve lash. I know that i have hydraulic lifters so i'm a bit confused as to why i would have the adjustable setup??? My main question is what should i set the gap to using the feeler gauge, i was told it is possibly .014"? Any help would be greatly appreciated.

 

Step one is to figure out if you do have an adjustable setup. If your rocker studs have a larger diameter shank (non-threaded portion) than the thread diameter, your setup is non-adjustable. All you do is torque down the nuts to the recommended torque spec.

If the rocker studs are a constant diameter from top to bottom, your setup is adjustable. In this case, you tighten the nut until there is no VERTICAL play in the pushrod (zero lash), then go 1/2 a turn more. This needs to be done on each rocker at the base of each cam lobe, so there's a certain order you need to do things as well.

 

If you have hydraulic lifters you don't need feeler gauges. You want zero lash +1/4 turn.

Finding zero lash is pretty easy. Turn the adjusting nut with your fingers. When you can't turn it any more, that's zero lash. In the olden days, you tightened the nut until you could not spin the push rod with your fingers. But with today's materials and lubes, that doesn't always work.

The lifter must be on the base circle to do the adjustment. Finding that is also pretty easy. Turn the engine by hand until the intake valve is halfway towards closed, and adjust the exhaust valve. Turn the engine until the exhaust is half way to closed, and adjust the intake valve.

http://www.compcams.com/Technical/In.../Files/250.pdf

 

Ford spec, and almost all aftermarket cam makes, is +3/4 turn.

 

I have seen 1/4 turn for stock and 1/2 to 3/4 turn on after market.

Keep in mind that hydraulic lifters leak down.

If you adjust valves cold it is advisable to pump up lifters frequently by spinning oil pump thru distributor port. Don't drop pump shaft into pan.

You can adjust hyd lifters while engine is idling.

Cut access holes in a junk valve cover.

Find point where clicking ceases; this is zero lash.

Turn adj nut CW 1/2 turn; done.

Advantage of adjusting lifters while engine is running is you can verify all rockers are getting good oil flow.