after machine shop shaved head... no compression on #2

[vballfun]

I've got a '95 vortec 6 cylinder.. that I recently had a blown head gasket on (the driver side head)... In the process of trouble shooting this.. I had the heads shaved. When I put the heads back on I now have 0 compression in the #2 cylinder where before I had around 120-150 psi on every cylinder.

It seems like when I torque the rocker arm retaining bolt down to the 20 ft-lbs required for this engine (no lash adjustment supposedly possible) one of the valves in #2 stays open so I get no pressure.

Has anyone run into this before?? did the machine shop do something 'wrong'?
Is there supposed to be some 'lash' between the rocker arm and the valvestem on these vin w engines? chiltons says there is no adjustment need or even possible.

help!!

-vballfun

[534BC]

Probably the head and a valve that is faced thin and a seat that is sunk. All these added together can hold valve open. Fix can be a thick/new valve, new seat, short pushrod, rocker spacer, face off the valve stem, ect. anything to allow some clearance.
As a test you may back off the bolt and crank engine testing compression, that'll tell if you're on the right track, I think you are.

[vballfun]

I'm thinking that when they did the valve job on it.. they honed the valve seat a tad much on that one cylinder... and did not adjust the valve stem length accordingly... the rocker arms on this engine are not adjustable.. just torque them down to 20 ft-lbs and it is supposed to be 'good to go'. I did try just 'finger' tightening the rocker arms until they -just- touched the pushrod tops.. and I did get compression.. but I can't run them that way the nuts aren't gonna stay put.

I talked to the machine shop and they said to bring it back in.. they have it now and are going to look into it.

I hope they find something.

[534BC]

I think you are right, the valve was probably sunk and required the seat and valve to be ground too much. They should mix and match the lowest hole with the highest valve.