, I am working on a 1969 cougar with a 351w. The problem I have is rocker arm noise. I originally thought it was lifter noise so I replaced the hydraulic lifters and am still having the problem. What I also discovered was that on one head the fulcrums for the rocker arms half slide up and down the shaft freely and the other half are snug and were difficult to remove. should they be tight or slide freely? The shafts are the shouldered type and the book says to mark my balancer in 3 spots and rotate then torque rocker arm bolts to 18-20 lbs. Any suggestions? Thanks! Mike
Sounds like you don’t have the valves adjusted correctly. If I remember correctly (check your manual) I slowly rotated the crank until the valve I wanted to adjust was at it’s highest or closed position then tightened the rocker down untill there was no slack left between the push rod and rocker. Then give it another half turn.
Do that for all of them. You should be able to adjust 2 or 3 at a time/turn of the crank. By the way rotate the crank using a socket wrench and not the starter.
Welcome to the forum!
Thanks for the info but these valves are non adjustable. The rocker arm shafts are shouldered so it says to rotate engine to close valves and actually torque to 18-20 pounds. The shafts are made to have the bolts bottom out on the shoulders. I believe the valves you are referring to are the type that are double nutted correct? These have a single nut. I have adjusted those valves before and these are different. I am just really trying to avoid a valve job. It just occurred to me that the shafts are press in and maybe they are pushed out so it is not putting enough pressure down on valves. I will have to check this out tomorrow. Any more ideas are greatly appreciated. Thank you for the welcome! I am glad to have been referred to the forum by West coast classic Cougars!
Yes, the rocker studs on a stock 351W are press-in, and can pull out of the head, throwing off the valve adjustment. Usually its not a problem with a stock valvetrain, but high-lift cams and stiff valvesprings can cause them to loosen. Its easy to check. Simply lay a straight edge over the top of the studs, and if one is sticking up more than a few thousandths above the others, there’s your problem. Unfortunately, there’s no easy fix, short of pinning the stud or converting it to a screw-in style. Both of which require machine work, of course.
Otherwise, if the geometry is off simply as a result of previous valve jobs, having the heads shaved or block decked, etc., it can be brought back into adjustment by changing pushrod lengths. But if a stud has started coming loose, that will be a temporary solution at best.
Thank you for the replies. Any info on the fulcrums? Should they be tight on the shaft or slide freely?
They should slide freely (or have very slight resistance) on the threaded 5/16" portion of the stud, and bottom out solidly on the lower 3/8" portion.
That’s what I figured. My fulcrums will slide all the way down the 3/8" smooth shaft. I will replace them. Thanks!
Heck with that…time for new heads.
Ouch! I hope not!