Them Ain't No Pushrods

Looks like a 356, but it don't sound like a 356.   I've waxed poetic about the Type 547 series 4-cam before: it has a throaty growl at middle revs and a blare higher up.  Sounds bigger than it's 1.5 to 2.0 liters.  It won a ton of class victories for Porsche from 1954 to 1964 in Spyders and the 904.  Here's some goood audio:

http://www.youtube.com/watch?v=kqV6gaEtzdE

The race engines usually ran Weber carbs (these look like Solexes with a hokey air-trumpet attachment).

The later, larger, engines had square cam covers and different Type numbers (through 692, I think).  Some had shell
bearings instead of roller cranks.  The view above shows the housing for the shaft drive to the upper camshaft.  The
cutaway view below shows the Type 547 series' signature feature of bevel gear-driven shafts, from a layshaft below
 the crank, to spin each of the four camshafts.  They all had twin-plug ignition.