Quote:
Originally Posted by Dragoneye
The cams push down on rocker arms which pivot, and push down the valves. It looks similar to an OHV engine's setup, except the rockers are ancored at one end, touch the valve on the other end, and get pushed by the cam in the middle. I don't think any OHC engines act directly on the valve stems...I could be totally wrong, though.
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Indeed, you are wrong.
My '00 DOHC Mazda Miata has solid, direct acting bucket cam followers that are mounted directly above the valve and the cam lobe is directly above that. The valve lash is set by measuring the clearance and replacing removeable shims till the lash is within limits.
Many high-reving engines are made like that and many european race engines incorporate that design since it is about as low-mass as it is possible to get. It does make setting the lash more difficult but it is also possible to have hydraulic (self adjusting) cam followers with that design. Early Miata's did just that. The mechanical type was better and actually more reliable long-term though.
But, because of the difficulty setting lash, many OHC engines do use rocker arms, just for the ease of setting lash. I don't like it but it does make for more simple maintenance, even if it does increase the mass of the reciprocating parts.
I wouldn't even want the push rod V-8, even if it was cheaper, just because the V-6 has a better induction system and a much better valve train. You really can beat cubic inches. It just takes technology.