[George440]

I got my open chamber heads back fro the shop 18 months ago and and after after the engine started and settled down i noticed a clattering after a medium reving of the engine. I have a very tame cam and new hydraulic lifters with 65 PSI oil pressure. The engine runs smooth besides detonation, but thats another topic. I suspect valve lash. Where can I find the spec for valve stem protrusion. I had him level the valve stems but I don't know if he kept them in spec. Does anyone know where I can find this information. I know there is a tool to place around the stem before install, but I don't have it. Would it be safe to use lash caps on the stems? As long as there is no coil bind of course.

-George

 

[Moparmatts72]

What heads are you using? Stock valve train or did you go roller rockers? Are you sure its detonation? Check timing see what it is. Can you isolate where the noise is coming from?

 

[George440]

The heads are 3462346 a 71-73 head and the chamber was measured at 89cc. I had the exhaust valves replaced, so I think that changed things from stock. And new hardened valve guides. The ping is from the too high a compression, pistons, 11:1, calculation error. I have stock 9:1 pistons ready to be installed, as the whole reason for the the engine tear down. The timing can only be safely be set to about 3 degrees and I still can't floor-it without knock on 91 octane. Even with 100 octane, I can still hear the knock at 7 degrees. All new roller timing gears from edelbrock for their cam.

The clatter is definitely in the valve train. Stock stamped rockers.

I really just need the protrusion height information to do some checking.

Thanks for any help.

 

[Ddaddy]

As with any new head with a different valve, you should check valve to valve and valve to piston clearances. Protrusion is related to the total cam lift for intake and ehaust and can't be estimated without that information.

 

[George440]

The cam is Edelbrock Performer-Plus Hydraulic, Part#: 2192
Lift at cam: Intake .280", Exhaust .295"
Lift at valve: Intake .420", Exhaust .442"