On Mon, 25 Feb 2008 19:39:11 GMT, "William W Western"
wrote:

with the manual choke. Youngsters these days don't seem to get the
concept. Neither do they understand what a carburetor is and does.
Hard to imagine you would need a rich mixture to get the thing lit
in your climate. I do not miss carburetors all. snip

Ah, but you do. You see, the stratified charge engine, successfully
mass produced by Honda after Ford said it was impossible, uses a "pre
combustion" chamber near the plug, fed by an auxiliary, small "rich"
venturi, complete with separate manifold runners, running at around a
13:1 mixture, which is easily ignited under all circumstances. The
main venturi, actually the primary (it's a 3 bbl., actually) feeds the
main combustion chamber through a more conventional intake valve from
conventional manifold runners, and has a mixture of around 16:1 or
higher. Such a lean mixture cannot be successfully be "lit" by a
spark plug, but is well ignited by the wall of flame coming from the
auxiliary chamber. Thus, Honda was able to forestall installation of
catalysts on their CVCC (Controlled Vortex Combustion Chamber) until
1979 in California, and the early '80s in the rest of the US. Canada
had the conventional engine sans CVCC on these cars.

With such a light mixture, a choke must be used to keep it running
smoothly during warmup. Prior to 1978, Honda hadn't yet devised an
automated system using an electric choke element that would satisfy
all conditions, so a manual, calibrated choke was used..."one click"
for mild weather when starting cold, two for colder weather, and full
closed for very cold or long periods of sitting.

It's a fascinating engine, really, misunderstood by most, but once one
gets the gist of the design and knows the tricks and foibles, it's as
good as any other. One thing that gave the CVCC a bad rep with
careless owners were the auxiliary valve body seals for each cylinder.
The o-ring material wasn't up to the heat generated around the valve
body, and they'd shrink, causing excessive oil consumption. Fel-Pro,
some years ago, developed tougher Viton® o-ring seals that obviated
regular replacement. Ditto the stock camshaft timing belt; the OEM
belts were notoriously weak and would peel apart at 30K miles or so,
and 24K mile belt changes were recommended. Aftermarket belts last
50K or longer.

The kid just got the Accord with a new timing belt and tensioner, plus
a whole set of Fel-Pro valve body seals, so I expect he'll get quite
good service for some time to come, as long as he keeps the car
maintained well. My '75 Civic CVCC got over 180K miles on the
original engine with little problem, and I'd expect this one to get
even more. Weak spot: cracking exhaust manifolds, an expensive
problem to fix through swapping out for new, but the manifolds can be
drilled and pinned in the usual fashion, thus saving around $700.

It's still getting 29-30 MPG around town...try THAT on a new Honda! It
doesn't happen. Oh yes...the AC still works quite well as well, as
I'd just installed a new expansion valve about three years ago. Frigid
air, every time.