Valve heights.

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datzenmike
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Valve heights.

Post by datzenmike »

Exhaust valves are just under 0.050" longer than the intakes.
Exhaust valve seats are almost exactly the same 0.050" thicker than the intake seats.

My questions are...

Are stock exhaust valves installed 0.050" more into the combustion chamber than the intakes so that the valve retainers and lash pads can be the same height? .048" to be exact, this is a little thicker than your thumb nail and hard to tell.

If intake and exhaust valves have different heights then are two different lash pads needed to get the cam wipe pattern centered? I've had heads apart and didn't keep track of which lash pad went where.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
Three B's Racing
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Re: Valve heights.

Post by Three B's Racing »

I'd say yes to your question about lash pad and retainers all being the same. If the exhaust valve is .050" taller and the seat is .050" thicker protruding into the combustion chamber that would keep the valve stem tip heights of all the valves the same or close. So yes to keep the same valve heights so retainers can be the same as well as lash pads. Speaking of lash pads, likely you will not use the same thickness lash pads for all valves unless your really really good at head work.
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datzenmike
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Re: Valve heights.

Post by datzenmike »

It was a quick dismantle and lap the valves while doing other things to the engine. The head was in good shape so I slapped it back together. How does an L head come from the factory?


I looked up lash pad part numbers and it seems like there is only one for int and ex.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
Three B's Racing
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Re: Valve heights.

Post by Three B's Racing »

datzenmike wrote: 22 May 2021 20:43 It was a quick dismantle and lap the valves while doing other things to the engine. The head was in good shape so I slapped it back together. How does an L head come from the factory?


I looked up lash pad part numbers and it seems like there is only one for int and ex.
Yes one lash pad for exhaust and one for intake. Stock factory pads were all the same thickness and were concaved on their bottom end. The newer thicker pads required for performance cams to correct rocker arm geometry are of various thicknesses and are flat on their bottom ends. Are you saying the pads you looked up are all the same thickness and shape?
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
- John Lennon
datzenmike
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Re: Valve heights.

Post by datzenmike »

Now I'm confused. You say one size for intake and one for exhaust, then... all pads were the same thickness.


13218-A3500 is listed qty 8 used

13218-21010 is listed as an 'over size', qty 8 used

Nowhere does it specify intake or exhaust.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs
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