Valve lash won't stay adjusted

[Charley Beckman]

I have a 292 bored to a 312 and 312 heads with solid lifters. After adjusting the valves a 20 minute run at 65mph and a few of the rocker arms come loose. The adjusting bolts have no kind of lock down nuts.

I'm wondering if I'm just dealing with worn threads on the adjusters, worn threads on the rocker arms or could I have a timing issue that does not allow me to use enough of the adjustment thread to get the proper bite?

 

[gbhrps]

Charlie,
My 55 has its original tappet adjusting screws and locking nuts. In 56 Ford went with tappet adjusting screws that were self-locking. I have an older National Parts Depot TBird catalogue and it lists the 55 as "screw, tappet adjusting, used with locknut" for the 55, and "screw, tappet adjusting, STD, self-locking for the 56/57". I'm at a loss as to what you may have, or may be missing.

 

[Charley Beckman]

Since i have the 312 heads they would have to be at least 1956 or newer. I found a set of remanufactured rocker arm assemblies today so I think I'll just replace them and go from there.

Thanx