Well, since I had most of the car apart I figured I would change out the factory original valve seals. Now the question is, is it possible to make the valve lash too tight?

Following the book, turn until you feel drag (not exactly clear on if this means just when you start to feel resistance or just before you the rod stops turning) - then add 1.5 turns. Now regardless, it seems that some of the nuts are 'tighter' more than they were before based on the number of threads showing (I didn't do a measurement or anything, just a visual).

Am I missing something or could this simply be normal (just valve seal were changed, no other work done to the heads as the compression test was good)?

Thanks,

yes, it sure is possible to tighten to far.

and, yes, the "until you feel drag" is WAY vague. reality is - at zero lash - you dont feel drag. plain old impossible. which is why most people dont go the full 1.5 - because hitting zero lash is impossible. the actual goal of lashing is to get the piston inside the lifter 1/2 way down the bore, when the lifter is sitting on the base of the cam.

When adjusting lash be sure to rotate the crank to move the lifter off of the cam lobe. The lifter should be on the base circle part of the cam. Tighten until you feel just a LITTLE bit of drag (I guess the CAPS make it less vague), and then tighten to published spec.

Kinda like installing an oil filter!

...ok, then the question is what is a little bit of drag? I know, it's one of those feel things - be nice if it was a simple measurement...

guess I will try playing around with it again...

[This message has been edited by Mickey_Moose (edited 05-24-2011).]

yes, that "little bit of drag" is mighty tough to spot if there lifters are already oily.
some folk do this by jiggling sideways, instead of by twisting. what you are looking for is that magic moment where there is no slack at all - and yet - no compression on the lifter plunger. Zero Lash. It is an impossible feat to get 100% correct. but - that is the whole point of hydraulic lifters - to compensate for the slop. so - dont worry about it to much. usually, this is done in sets of 6, 6 during TDC #1, 6 during TDC #4. if you are doing TDC #1, when done, look at a lifter from the TDC #4 set which is fully pushed in. thats max depth. the lifters you did should be pushed in roughly 1/2 that depth, and consistantly pushed in.

I find the jiggling sideways is the best way too. You have to remember though, that the 1.5 turns is for a brand new motor. Not one with wear. I think on an original cam I'd go a bit lighter. You really lose power fast if they are too tight, and they have to be pretty loose to rattle.

Arn

Don't use the spin-drag technique, that only works if you have lots and lots of experience and practice, or a surgeon's touch. Instead, pull the pushrod up so that the slack is taken out of the rocker arm and then wiggle the bottom of the pushrod side to side, like a blind man using a cane. You'll feel the "tap, tap" as the end of the pushrod taps either side of the lifter poppet recess. As you tighten the rocker nut you'll feel the distance decrease until suddenly it's gone. Remember, always pulling up, never pushing down. At this point you're at zero lash. Turn the rocker nut 1.5 times and you're done. Make sure the lifter is on the cam base circle, this is critical.

quote Originally posted by Arns85GT: I find the jiggling sideways is the best way too. You have to remember though, that the 1.5 turns is for a brand new motor. Not one with wear. I think on an original cam I'd go a bit lighter. You really lose power fast if they are too tight, and they have to be pretty loose to rattle.

It makes no difference if the motor is worn, the idea is to get the poppet in the middle of its travel so that it has the best range of self-adjustment for various changing conditions in the motor such as thermal size changes (pushrods get longer as they warm up, for instance). Power cannot be affected by adjustment unless improper adjustment causes the poppet to hit either end of its adjustment range. 1.5 turns puts the poppet halfway down the lifter body.

[This message has been edited by JazzMan (edited 05-24-2011).]

Rather than doing it of of #1 and #4 as suggested above, do each valve individually. Rotate the crank until both valves are closed and have at it.

The wiggle method also works.

And yes, you can get the lash too tight.

Too tight = power loss. The reason is the seating of the valve. Too tight and it doesn't seat completely or soon enough.

I put in ARP bolts and I use the SBC setup with 1/4 turn. I have used the 1.5 turn on the regular studs and it always makes me feel like it is too tight. Once it really was and I ended up at 1.25 turn.

Arn

Wouldn't 1/4 turn preload cause the lifters to clatter when cold? Is there any advantage to leaving the adjustment on the loose side?

I have done many engines with the 'TWIST' the pushrods method. Once I learned the 'TAP-TAP', side to side, I have changed. The TWIST is still good to get in the 'Ball Park' for the TAP-TAP. They are not real loud if you have assembly lube on the ends of the push rods, so you might want to listen real good, and turn off the radio while setting the lash.
-Joe

http://www.youtube.com/watch?v=89o5rLpbCgI

Different engine, but basically the same.

...ok...first thanks to everyone that offered some input.

I will give it another go tomorrow - got distracted cleaning up the wiring harness, but I did back off all the nuts (I am sure some of them were probably too tight).

...anyways, thanks again - hopefully I can get it right (I like the self adjusting motors like the 4.9 ).

Cheers

quote Originally posted by JazzMan: ... pull the pushrod up so that the slack is taken out of the rocker arm and then wiggle the bottom of the pushrod side to side, like a blind man using a cane. You'll feel the "tap, tap" as the end of the pushrod taps either side of the lifter poppet recess. As you tighten the rocker nut you'll feel the distance decrease until suddenly it's gone. Remember, always pulling up, never pushing down. At this point you're at zero lash. Turn the rocker nut 1.5 times and you're done.

This method is the easiest way for most people to set lash correctly. The spin/drag method does work too, but it requires more experience and/or a more delicate touch; most people get the lash way too tight using the spin/drag method.

quote It makes no difference if the motor is worn, the idea is to get the poppet in the middle of its travel so that it has the best range of self-adjustment for various changing conditions in the motor such as thermal size changes (pushrods get longer as they warm up, for instance). Power cannot be affected by adjustment unless improper adjustment causes the poppet to hit either end of its adjustment range. 1.5 turns puts the poppet halfway down the lifter body.

Right ... and for the right reasons. There will be no difference in engine performance as long as the plunger in the lifter body is within its travel limits.

[This message has been edited by Marvin McInnis (edited 05-25-2011).]

seems like if the preload was so picky, then you would do it by adjusting the amount of preload. like say mounting a dial indicator to see how far down the plunger is going

I did the full 1.5 turns on mine. I didnt see anything about it being on a new engine or not until this thread

quote Originally posted by scott0999: seems like if the preload was so picky, then you would do it by adjusting the amount of preload. like say mounting a dial indicator to see how far down the plunger is going

You are correct. That would be the most precise way to do it, but it would require a dial indicator and the process would be slower. There is enough travel range built into the lifters that the "zero lash + 1.5 turns" method, done properly, gets you close enough to optimum that any other method would be overkill.

[This message has been edited by Marvin McInnis (edited 05-25-2011).]

quote Originally posted by Mickey_Moose: ...ok...first thanks to everyone that offered some input. I will give it another go tomorrow - got distracted cleaning up the wiring harness, but I did back off all the nuts (I am sure some of them were probably too tight). ...anyways, thanks again - hopefully I can get it right (I like the self adjusting motors like the 4.9 ). Cheers

The 4.9 uses similar lifters, except they may have roller tips, but the hydraulic self-adjustment system is identical. Repeated adjustment isn't normally necessary for hydraulic lifters.

This is how I set valve lash.

One cylinder at a time, I rotate the engine till one valve is at full open, then set the lash on the closed valve. Tighten the rocker JUST UNTILL the up and down play is gone, then 1 to 1.5 additional turns. Repeat for all additional valves. I find it helpful to mark the set rockers with a dab of paint so you don't get mixed up. You could also use a crayon or magic marker, but the marker might be hard to see?

Once you have them all set, you can count the exposed threads of the rocker stud (above the rocker nut), they should all be pretty equal, and a good "rule of thumb" is that you should have three threads exposed above the nut. If one is way off from the others, you should re-check it.