Vintage Mustang Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
HI All,

I am installing new Edelbrock heads, roller arms and intake manifold on a 66 289. I am using the stock tappet cam and lifters and they were just left in the engine for this work for this quick update to the motor. I am reading the adjusting valve lash instructions and I appear to have an issue. The instructions state to adjust to Zero lash, then add a 1/4 to 1/2 turn additional, which will depress the spring in the lifter. The valve should remain closed. My lifters have been run in the engine and are fully pumped up and wont depress the lifter spring. I thought about just buying new tappet lifters but everybody I talked with said this is risky as it can wipe the cam. The lifters need to stay with each cam lobe.

I think the only solution is to find a way to get the lifters to release the hydraulic pressure and depress the lifter spring. Does anybody know if this can be done with the lifters in the block, or do the lifters need to be removed and disassembled to release the oil pressure?

Thanks, Mitch
 

·
Registered
Joined
·
3,622 Posts
No need to release oil in lifters.

First, welcome to VMF. You will find a wealth of information here.

To adjust preload (proper term for hydraulic lifters, lash is really for solid lifters):

1.) Rotate engine so that the valve is fully closed.
2.) Jiggle the pushrod up and down as you tighten the rocker stud. When all play is removed then tighten 1/4 to 1/2 turn to add the appropriate preload. (don't use the "spin the pushrod" method to check play. You will add preload with that before you ever get the pushrod to stop spinning)
3.) Move on to the next one...

There are some youtubes showing how you can adjust a couple valves at a time before rotating the engine. That will save some time.
 

·
Registered
Joined
·
4,986 Posts
i will say if you are not use to adjusting valves, anytime you have the intake off it is really easy to do as you can actually watch the lifter and see what is happening. Nothing wrong with the spin method if you have experience but you need to have some oil on your fingers to get the right feel.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #4
Thanks for the replies guys. It was youtube video that I was watching prompted the question and made sense to me. In this video the point is made to work with a dry lifter to add preload. See this video and go to the 8:34 point in the video.
The lifters are spongy when dry and allow the push rod to compress the lifter spring. My concern is the lifters are hard now and won't compress. Maybe they will. I have the correct length push rods on order and should be here in a few days and i'll find out for sure then when I start the valve adjustment.
 

·
Registered
Joined
·
3,622 Posts
Valve trains are removed and replaced all the time without removing and draining the lifter before adjusting the valves. The downside to the lifter being full of oil is that when you turn the crank some of the valves will open.

If you feel compelled to removed and drain the lifters, remember that flat tappet lifters must, must , MUST be placed back in the same hole it was removed from or you will trash the cam and lifters.

BTW, you will not know if you have the correct pushrods when doing valve adjustment unless they are way off. You can look up the procedure for determining proper pushrod length, but it involves marking and checking the pattern the rocker tip makes as it moves across the top of the valve stem.
 

·
Registered
Joined
·
3,245 Posts
Forget about draining the lifters and go ahead and just set the valve lash. I’ve done this many times and never heard of draining the lifters. As Nike says, just do it!
 

·
Registered
Joined
·
3,245 Posts
1 - 8 of 8 Posts
Top