Adjusting Hyd Valve lash

68 Fastback · #1 (**permalink**) 11-03-2009, 07:02 AM

Question: On a fresh rebuild do you adjust the Hyd valves with them dry or with oil pressure?

I would think it is with oil pressure. Note: I will build the oil pressure by priming the oil pump, not starting it.

Thanks

blykins · #2 (**permalink**) 11-03-2009, 07:23 AM

Both.

Set them dry and then run them again when you get the engine hot and run it for a bit.

The procedure is the same for both dry and under pressure. Adjust so that there is zero lash, then crank about another 1/2 turn into it.

Note that some people think that you can't turn the pushrod when you've achieved zero lash. That's not true...you're looking for no axial movement at this point.

philminotti · #3 (**permalink**) 11-03-2009, 08:44 AM

FWIW-

I attempted to set the lash on my hydraulic roller lifters after I preoiled the motor (new build) and had trouble with some lifters not bleeding down. I'm not sure what caused this...maybe some assembly lube that I put on the ends of the pushrods got into the lifters and gummed up the works...I don't know...but I had to pull my intake. Not fun. Needless to say, I set my lash prior to preoiling and avoided assembly lube on the pushrods (just motor oil).

phil

bobcowan · #4 (**permalink**) 11-03-2009, 08:55 AM

Quote:

Originally Posted by blykins

Both.

Note that some people think that you can't turn the pushrod when you've achieved zero lash. That's not true...you're looking for no axial movement at this point.

I agree 100%. That's the old way of doing things. With modern lubes and materials, that doesn't work any more.

I run the nuts down by hand, not using a wrench. When I can't turn the nut by hand, that's zero lash. Then add 1/2-3/4 turn with a wrench.

DAVID GAGNARD · #5 (**permalink**) 11-03-2009, 10:28 AM

I set them before starting the motor(just as the others have advised), do a 15 to 20 break-in and then shut things down and let things cool off a bit......

I took an old factory steel valve cover years ago and cut out a strip about 2 inches wide in the top, the length of the valve cover.

I then install this valve cover on one side, start the engine and begin re-adjusting each valve........First I loosen one nut at a time till I hear the valve "ticking" and then slowly tighten that one, when the "ticking" stops, I add 3/4 turn and go to the next one.......

works like a charm, have one 351-W I did this on 6 or 7 years ago and the valve covers have not been off since...........

David