Quote:
Originally Posted by blsfrs
Element Tuning did my original build. I would have sent the engine back to them but they moved from Maryland to Florida and I wanted someone more local. I've been in touch with Phil concerning my problem and in our last communication the oil pressure vs lash question came up and he said: "If the lifter wasn't hydraulic the rockers would eject very quickly as there's nothing holding them in place securely. The oil pressure takes up the lash. That's why i made the comment about how he said the rockers are loose, as they are, but by how many thousandths. They pivots are in the oil pressure galley, then push up, exposing a relief port, and then there is also an oil port into the roller socket. The roller socket has barely a relief for oil to escape. On the cam's base circle you can wiggle the crap out of the rocker with only 5-8 thousandths (intake/exhaust) clearance but that's not loose, that's correctly lashed. I'm not saying you can't go tighter but you better have a good idea what your new valve seating recession will be after run it, what service interval you are trying to achieve, and what overall temperature you are lashing for as higher temps require looser clearances to deal with expansion." Seems logical.
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To me, I would probably defer to Phil. Although it still doesn't seem to make much sense to me. Stock valve lash specs are .004-.006in intake, .008-.01in exhaust. That is pretty much in line with what a DOHC direct actuation setup runs. So I don't see the need for oil pressure to take up any additional lash unless there was something I am missing. I am aware that the rocker pivot sits in the oil galley. An early change to these engines actually had to do with the rocker pivots, I believe the oil hole in the passenger head was larger then the pivots in the driver side head. These were later updated to be the same size on both heads.