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I've never had the lash not grow when hot on an aluminum head combo....you have an interesting scenario there. I can always count on my iron block/aluminum head combos growing about .006" when hot. All-aluminum FE's grow about .011". My all-iron stuff either does not grow or it grows a few thou.
Patrick, all lash specs are always given as hot. You can remove the lash, then check valve lift at the valve, then divide by the rocker arm ratio to get lobe lift. Measuring duration at the valve is going to be tricky, but it can be done with a degree wheel and some patience.
Lash specs are derived from taking the lash ramp and multiplying it by the rocker arm ratio. You really need to talk to the cam grinder to get a dead on spec, but unless it's a tight lash lobe, you're pretty safe in the .025-.030" range.
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