Re: alfa-digest V9 #259

[Will Owen <nashwill912@domain.elided>]

Paul Misencik asked:

"Is there some theoretical advantage to pushrod engines that I'm not getting
here?  Why do American manufacturers continually go back to the drawing
boards, create brand new engines from scratch and spend tens of millions of
dollars to create all-new pushrod engines?  With cars like the Corvette, is
it just to satisfy the purists?

"There are overhead cam engines that are torquey, cheap to build and
reliable.  Why build a 21st century passenger vehicle engine that uses
pushrods?"

The advantages aren't theoretical, they're practical. Pushrod engines can be made lighter, maintenance is in many respects easier (hence cheaper), and as long as you aren't expecting a valve to follow a radically ground cam at 7000 or so there's not much
reason for OH camshafts in your everyday cooking engine. I suspect that many of our current family-car engines have their camshafts upstairs because that's what folks expect nowadays. It's a fashion, like, say, SUVs... but pushrod engines can put out
ENOUGH horsepower, which is really all that's important on the street. And let us not forget that the original Ford Cosworths were pushrod OHV, and ran reliably at 7K and over.

We tend to think of our machinery the same way we tend to think of evolution, that it's all headed for perfection, and any return to a previous model is necessarily a step back towards Ignorance. Ain't none of it necessarily so, kids. Even the old
flathead had its advantages: the magnificent OHV narrow-angle V16 that Seaholm designed for Cadillac in the late '20s was replaced in the '30s by a wide-angle sidevalve one...which weighed considerably less, ran much more quietly, and got more horsepower
out of less displacement.

That said, I'm sure glad my Milano has its cams where they are, even though it has some pushrods, too. I just don't particularly want to do any of the adjusting, that's all...

Will Owen
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided