Valve tip clearance vary .045???
10-10-2011, 10:06 PM
#1
Valve tip clearance vary .045??? I happened to take a straight edge to the tips of my valves installed in the heads and got an interesting result. The intake valve tip is .045 lower than than the exhaust valve tip. The valves are the same length. Either I'm missing something here but wouldn't that mean I need to use different length push rods or take my heads back to the shop and have the intake valve sunk in the head .045? I'm pretty sure the rocker stands are all machined the same right?
I have never really inspected this aspect of the LS1 heads and may be common. Enlighten me please!!
Note: These are ETP 215 cathedral port heads fresh from the machine shop
I have never really inspected this aspect of the LS1 heads and may be common. Enlighten me please!!Note: These are ETP 215 cathedral port heads fresh from the machine shop
10-10-2011, 10:59 PM
#2
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All the intakes or lower or just one?
Whether you would need to run different length pushrods would be determined after preload/length is measured and verified.
Whether you would need to run different length pushrods would be determined after preload/length is measured and verified.
10-10-2011, 11:53 PM
#3
0.045" difference seems like a lot. I'm pretty sure that the valve tips should ideally all be at the same height; as all the rocker arms, pushrods and lifters are identical so there's no compensation in those parts for different height intake vs exhaust valve tips.
Wondering if the machine shop didn't set something up right when dong the valves.
Wondering if the machine shop didn't set something up right when dong the valves.
10-11-2011, 08:49 AM
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When I had a valve job done they ground the valve tips to maintain proper valvetrain geometry, since the valve is recessed in the head and they're "longer" on the rocker arm side. In retrospect, this is probably a bad idea as you could grind through the hardened outside. The difference in lengths could have been the result of careless grinding of the tips.
10-11-2011, 09:21 AM
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The funny thing is that I looked at the valve tips and they were no longer perfectly formed square ends but had a rather hand ground look to them. Though it wasn't sloppy you could tell they had been ground with a wheel or something. I could see taking a tip down in length if you knew the exact amount that the valve was recessed in the head with the new seat, then put the valves in a lathe and cut the correct amount off the tip to compensate. Putting a valve tip to a grinding wheel just seems wrong for so many reasons.
Last edited by 01ssreda4; 10-11-2011 at 04:43 PM.
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10-11-2011, 11:47 AM
#9
Just checked a set of factory 799 cnc ported heads. The same thing there as well just a little less, .030 difference instead of .045. Lifter preload makes sense determining pushrod length now that you mention it. I'll have to mock everything up and check preload and rocker tip travel on the tip of the valve. Maybe its not uncommon as I thought