Jim

I only posted a bit of triva. Am sure no one on thread had ever heard
of the problem.

Your right, long stacks or a muffler would prevent the valve warping,
like on the Merlin, today either with an air or liquid cooled
engine.???

Big John

On Wed, 29 Oct 2003 14:44:44 -0600, Jim Stockton
wrote:

Big John wrote:

Del

A true story that probably could be included under shock cooling.

In the P-51/Merlin (liquid cooled) we used to pitch off the deck (50
--100 feet -- 250 mph +/-) into the landing pattern. As we pitched up
we pulled the throttle to idle and the Merlin would go 'poppety pop'
out the short stacks all the way around the pattern (wonderful sound
to listen to G)

Some one got to investigating warped exhaust valves and found that the
valve timing was such that the engine sucked a lot of outside air
(cold) into the cylinder thru the exhaust valves at idle and with the
valves being 'hot' from cruise power, the cold air being sucked by
warped them.

Solution.

They let us only pull the throttle back to 10 --12 inches on pitch. If
you went 'poppety pop' in pattaern the Ops Officer would hear and chew
A**. As we flew around the pattern at the low power setting the
valves cooled and on final we went to idle for the touchdown.

Voila, no more warped valves.

So, Liquid cooling of an aircraft engine didn't eliminate all of the
'shock' cooling problems.

Big John

On 29 Oct 2003 03:22:42 GMT, Del Rawlins
wrote:

On 28 Oct 2003 05:51 PM, Dave Hyde posted the following:
Del Rawlins wrote:

----clip----

Not quite on the same level. Where can I get a liquid cooled Lycoming
for my Bearhawk? It's a little bit of extra weight to lug around, but
worth it to me. Others don't seem as bothered by the need to baby their
engine on a descent to avoid shock cooling, or the suicidal heating
system used in most GA aircraft (where a slight undetected crack can
lead to CO poisoning).

----clip----

John
The mufflers on this conversion would probably go a long way to
eliminate the problem of valve warping as compared to the short open
stacks on the mustang.
Jim Stockton