OHC engines go back a long way.  I believe Crosley had them 50-60 years
ago in little 4 cylinder engines. Mercedes used them in some of their
Grand Prix cars of the war years and slightly thereafter.  These cars pumped
out amazing horsepower for their time, and the Germans bragged for decades
about their technology, desmodromic valve systems, etc.  Ford made
gigantic V8 OHC engines for tanks, having pistons damn near the size
of gallon jugs.

SOHC and DOHC designs can both be used in V configurations.  Are they
more expensive? Maybe.  There is some tradeoff between an extra cam or
three against a set of several pushrods and lifters, but OHC is probably
somewhat more expensive.

Are they less troublesome? Arguably.  When you decrease the number of
parts, you have the opportunity to reduce the time between failure.  (
Notice
I said opportunity.  Shitteaux parts and designs overwhelm opportunity all
the time)

As Don said, unless you are trying to extract the maximum out of an engine
configuration, OHC's are probably more important as marketing buzzwords
than anything else.

Not necessarily. You only need two cams for an OHC Vee engine, not four. You
can replace hydraulic tappets, push rods, and rocker arms with roller
followers (with hydraulic mounts). The block casting is less complex and
potentially lighter and stronger with simplified oiling passages. The cams
can be simpler. In either case the number of lobes on the cam is the same
(for a 2 valve per cylinder engine, the cam in block engine has 16 cam
surface to be ground, the SOHC engine has 8 cam surfaces per cam), so
machining costs are similar (or less in the case of press on cams like Ford
uses on the modular engines). With push rod engines, you have a tolerance
buildup related to the deck height of the block, the head thickness, the
rocker arms mounts , actual rocker arms, the valves, head gasket thickness,
etc that requires adjustability or alternate length push rods to absorb the
tolerances. With an OHC  engine, the hydraulic adjusted followers can
compensate for the reduced tolerance buildup (less assembly labor =
savings). The OHC cams are in a more favorable environment and more lightly
loaded, so they potentially can be less robust. The OHC cams are generally
easier to install in a manufacturing environment (less labor). The head
castings are simpler since they do not need to provide push rod passages
(but they do need to include additional oiling passages for the cam and
followers). With the OHC engine, you don't have to seal the valley between
the banks, so the intake manifold can be simpler, or you don't have to have
a separate part to seal the valley.

However, OHC engines are also generally larger on the outside which
translates into a need for more space in the engine compartment. OHC engines
(particularly Vee engines) require significantly more complicated drive
mechanisms (longer chains with automatic tensioners instead of a short
simple roller chain without a tensioner). For an equivalent displacement, I
suspect that given similar materials, the push road engine would be lighter
(and smaller in all dimensions).

It would be interesting to get a cost breakdown from GM for the SB Chevy V-8
engine and compare it to the cost breakdown for the Ford modular V-8 engine.
I suspect that the Ford engine has an advantage in the emissions area, but
costs more and develops less power than the Chevy SB for similar sizes. I am
guessing with equivalent maintenance the Ford engine will last longer, but
the difference is likely to be trivial. Either engine will outlast the
useful life of the rest of the vehicle if properly maintained.

I suppose I buy into the idea that a well designed OHC engine can provide
more power for a given displacement with better fuel economy and better
emissions than a push rod engine. However, I think it is hard to argue that
push rod engines can't be very good power plants. It is my opinion that when
you combine cost, external size, weight, ease of service, power,
reliability, etc., there is no current performance engine better than a
small block Chevy. Some of the more exotic engines might provide more power
for a given displacement, but they are also likely to be far more expensive
and less reliable.

Ed

Oh please! ANY time they review a car with a pushrod engine, they have
to call it "antiquated" even if it has more power and gets better
mileage than a comparable DOHC VTEC monkey-motion-machine.

Because "crappy American cars" traditionally have had pushrod engines,
and "cool European cars" have OHC engines. :-/

Of course those same people forget that the 1930s Duesenberg SJ series was:

- a 32-valve DOHC 8 cylinder
- Supercharged
- With aluminum connecting rods
- American

 :-)