Found this interesting patent concerning pushrod operating multiple valves and some of the inherent problems:
https://search.rpxcorp.com/pat/US7424876B2Specifically some of the problems this patent claims to address are:
Current four-valve-per-cylinder pushrod engines include
two intake valves and two exhaust valves for each cylinder.
Each pair of valves is operated in tandem by a bridged valvetrain
that includes a camshaft-driven cam follower (also
referred to as a tappet or lifter) connected by a single pushrod
to a rocker arm that drives a bridge coupled to the pair of
valves (intake or exhaust). This bridged valvetrain is a cost- 30
efficient design that achieves acceptable performance for
many applications, although operation of the two bridged
valves is not precisely synchronized because the force exerted
on the bridge can not be perfectly balanced between the
valves, the valves may have slightly different spring forces, 35
and the valve components may experience slightly different
wear. This may result in one valve opening late and/or one
valve may seat first while closing causing the other valve to
seat late with a higher than intended velocity. In addition,
valve stem tips are edge loaded by the bridge with higher 40
stresses resulting in higher rates of wear and potential noise,
vibration, and harshness (NVH) concerns.
It will be interesting to see exactly how the moco addresses these potential problems - hopefully better than they did with the twinkie and expecially its 110 variation.
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Topic: New 114 liquid cooled engine (Read 27207 times)