Quote Originally Posted by EUR003act View Post
you may be right, it was just interesting to me that the engines which have the lower redlines/weaker springs all have slightly looser clearances...
I suspect it might allow more time to safely ignore the valve clearance?

Sometimes valve clearances open up with wear, sometimes they close up with wear, depending on what surface is wearing the most quickly (i.e. wear on lobes / followers / valve stem tips causes clearances to open up, wear on valve seats causes them to close up).

My gut feeling is that it's probably safer to allow the clearances to get too big than too small, hence a larger clearance on a lower perfomance engine with a longer clearance service interval(???).

Or, maybe one engine model wears the lobes / followers etc faster (than the seats) and can tolerate smaller spec clearances because they tend to get bigger in service, but the other engine model tends to wear seats more so the clearance tends to get smaller in service, thus requiring a larger spec gap...???

Dunno, just thinking out loud..