v8bug

I am swapping a 2002 z06 cam into my 5.3 turbo motor. I have just replaced the valve springs with gm yellow springs, and the pushrods with comp cams hardened 7.4".

I am reinstalling the rocker arms and have torqued them too 22 ft/lbs, than rolled the motor over 180* and rechecked torque values.

I am noticing that some of the valves are not, or rather do not seem to be, fully closing. For example, the #2 intake valve opens fine and closes fine where I can just barely wiggle the rocker. The #2 exhaust valve however is noticeably compressed when it should be closed and is never wiggly.

I have rolled the motor over multiple times and hear/feel no valves hitting pistons. right now the spark plugs are out of the motor

So, could some of the lifters be stuck? or still have oil in them? I am really confused here

any help would be great!

thanks, Matt

SGT20

iTrader: (3)

Your exhaust valve lifter may not have bled down like the intake like you hinted at. What I would do to check the valve sealing is run a leak down test on the cylinder with it at TDC.

vettenuts

iTrader: (4)

That is not the correct rocker procedure, not sure where you got it. Lifter will bleed down in a minute or so. Is this the only valve that looks like this? If not, what are the others?

Here is the correct GM procedure:

G Engines

your pushrods may be to long and holding the valve open. Double check pushrod measurements, some cams may even require two different lengths one for the intake and one for the exhaust.

eallanboggs

iTrader: (1)

Are you sure both valves are on their base circles when you observe this anomoly? I don't believe 22ft/lbs is enough to bend a valve stem. Would you continue to turn the torque wrench if you started to feel a mechanical bind? I hope not.

hirdlej

iTrader: (31)

Twice now I've just torqued them all down without spinning the motor over, I've never had problems. The bolts bottom out as they should.

ae13291

iTrader: (8)

thanks VETTENUTS i needed that info on the rockers (=

vettenuts

iTrader: (4)

22 lb-ft is roughly 4,200 lbs at the bolt. If the lifter isn't bleeding down and assume its not moving, it would be less at the valve. My point being the forces aren't small.

However, I did miss one key point in the OP's post. The rocker can't be wiggled so the valve spring is still putting a force on it. If the valve were bent, the rocker would be loose so the valve should be OK. I modified my post.

DeanJ

iTrader: (6)

The lifters should be on the cam base circle when the rockers are torqued. If your pushrod won't turn now, wait for ten minutes then check again. If it won't turn now, you either have a stuck lifter, or your pushrods are to long. Hope this helps, Dean. P.S. this is for hydraulic lifters only.

DeanJ

iTrader: (6)

Vettenuts method will properly position the lifters on the base circle. However I would Not even install any of the rockers unless they Are on the base circle. Then Torque these rockers. I do not like to turn a engine over with ANY of the rocker bolts not torqued. Dean.