[350thunder]

Did initial startup and cam break in on fresh 496 yesterday for 20 min. After break in, let it idle for a while and then did a couple blips of the throttle. At the end I had a strange noise come from the rear of the engine and the motor bogged a little. I had my buddy shut the engine off. Decided to start it back up and oil pressure was great and it sounded great....smooth idle and quick throttle response. Did hear a constant clicking noise under drivers side valve cover and a crack or pop coming from the drivers side exhaust pipe. Decided to run the valves today to hopefully cure my problem. I am not very experienced with setting the preload on the hydraulic valves and have a question.

I am rotating the push rod until I feel some resistance, then am turning the adjusting nut 1/2 turn (180 deg). When I turn the nut 1/2 turn, I can look at the valve spring and see that the valve is opening. Shouldn't the pushrod be compressing the lifter? Whats wrong?

Thanks a lot

 

[Bob West]

I dont like the turning deal, I like to move the pushrod up and down until it wont move anymore then go with 1/2 turn preload, that is just to get it running. I then do it the dirty way and lash the valves with the engine running. The popping may have been from a lifter not letting the valve close completely,too tight,once the lifter is bottomed out the valve has no choice but to open.

 

[350thunder]

Ok, but when i get the play out of the pushrod and turn it 1/2 turn, shouldnt the lifter be compressing and not the valve? What would cause this?

Thanks for the help.

 

[Bob West]

Lifter is pumped up and full of oil? Maybe the lifter is on top of the lobe and its supposed to be open??? Just shootin from the hip

 

[yanniz]

i use the same method as you did....spin until slight resistance, then tighten down 3/4 turns (Morel lifters at .040" preload.)

make sure you are at the bottom of your lob and once you get there wait for a minute or 2 before you set your lash...

 

[66 BRONZE]

350thunder I set up my preload just like you did but that was just to get it running, after break-in I adjusted each valve hot with engine running, that was the only way for me to get the adjustment spot on.

 

[350thunder]

How exactly do you do it running and how big of a mess does it make?

THANKS

 

[Schurkey]

Given a choice, I adjust the lifter preload with the intake manifold OFF; before the engine is fully assembled. I can easily SEE how much the lifter plunger is depressed.

Having done that, I do NOT dick with it for many, many, thousands of miles. No "double-checking" of the preload after cam break-in, etc.

If there's excessive metal in the oil, the engine comes apart again. Who cares about lifter preload?

If there ISN'T excessive metal in the oil, the metal is still in place on the camshaft and lifter feet.

If the metal is still in place, the clearance didn't change.

If the clearance didn't change--why would I waste time verifying work I already know is right?

At the point where you are now, though, you certainly do need to verify proper preload.

The simplest possible way to do this is to pop the valve covers off, loosen any or all of the adjusting nuts for the rockers you feel it is appropriate to adjust; and then find the "zero-lash" point for any that you choose to loosen (only the one making noise--or all 16--or any number in-between. Just keep track of the ones you're adjusting.) As said in previous posts, zero-lash is better verified by moving the pushrod up 'n' down rather than spinning it; spinning it only tells you how strong your fingers are--not whether there's lash in the system.

Rotate the crank exactly one turn. Check all the rockers you've previously loosened and then re-tightened. Any that are NOT loose--leave alone for the moment. Any that now have lash, tighten again to zero lash.

Tighten all rockers that you have now worked on an additional 1/2--3/4 turn.

Put the valve covers back on, button up the engine compartment, put your tools away. You're done. Have a beer.

 

[Bob West]

Get car up to normal temp, shut off the car, remove valve cover,start car, start adjusting valves, back off rocker until it clatters, tighten until clatter stops then go an additional 1/4-1/2 turn is how I do it, some may go up to 1 full turn. I've seen old valve covers with the center cut out so oil doesnt spray everywhere or some parts stores carry little plugs you can put on each rocker where the pushrod goes to keep oil from spraying all over.

 

[Schurkey]

How exactly do you do it running and how big of a mess does it make?

THANKS

Hydraulic lifters:

Pull one valve cover off of a previously warmed-up engine. Install some form of oil shield--the "best" is an old valve cover that's had the top cut open for access to the rocker adjusting nuts. There is essentially "no" mess. Some folks use "Rocker-Stopper" clips that slide onto the individual rockers to deflect the oil spray downward--but then the oil will just drool down the side of the block and leave puddles on the concrete.

Start engine. Loosen each rocker nut until you hear it clack, then tighten until the noise "just" goes away. Move to the next rocker. Repeat for all 8 rockers on that bank. All 8 are now at the zero-lash point.

Shut off engine, tighten all 8 rockers an additional 1/2--3/4 turn. Install valve cover.

Repeat for the other bank.

 

[69-CHVL]

The best think to ever happen for hydraulic cam adjustment is poly locks - back them off, lightly run them down with your fingers till they just stop (this is zero lash), then turn the nut to the desired preload. I found that the crimped-nuts make it difficult to find zero-lash.

 

[SWHEATON]

along with valve/s out of avd the the poping/spitting can also be a partially fouled plug from fresh motor fireup and fuel mix could be a little rich and along with some oil getting past the rings too untill they are fully seated fouling the plugs.

Scott