Hydraulic tappets that "pump up" ... do they work?
Discussion
Just in case you can't guess it from what I'm about to ask, I know damn all about engines ...
I heard about some hydraulic tappets that "pump up". I get the impression that the idea is that at low revs the tappet has time to shorten meaning the valves open later and therefore for slightly less time. The point of this is to reduce the amount of overlap between the inlet and exhaust valve timing at low revs in order to make the engine smoother when a high performance cam shaft is fitted. At higher revs, the tappet doesn't have time to compress ("gets pumped up") and therefore the valves follow the timing of the cam shaft more closely allowing the overlaps to be increased.
Has anyone fitted these tappets? Do they work? They sound like they'd give a kind of stone-age variable-valve timing which might make it easier to live with a high performance cam. Almost sounds too good to be true, if they actually work.
I heard about some hydraulic tappets that "pump up". I get the impression that the idea is that at low revs the tappet has time to shorten meaning the valves open later and therefore for slightly less time. The point of this is to reduce the amount of overlap between the inlet and exhaust valve timing at low revs in order to make the engine smoother when a high performance cam shaft is fitted. At higher revs, the tappet doesn't have time to compress ("gets pumped up") and therefore the valves follow the timing of the cam shaft more closely allowing the overlaps to be increased.
Has anyone fitted these tappets? Do they work? They sound like they'd give a kind of stone-age variable-valve timing which might make it easier to live with a high performance cam. Almost sounds too good to be true, if they actually work.
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