Exhaust Valves

I am having my 0200A top end serviced for new rings, "miked" out for tolerances
and valves looked at and replaced as needed. My question is with 650 TT on the
engine can a careful visual by the certified overhaul shop satisfactorily
determine that the exhaust valves can still be reused rather than paying for
new ones ( at $125 apiece) ? I like to be safe but also reasonable about cost.
Thanks.

Larry

Only 650TT? Unless there's serious corrosion or a burnt valve,
there should be no problems with exhaust valves. Why does the engine
need work already?

Dan

wrote in message
oups.com...
Only 650TT? Unless there's serious corrosion or a burnt valve,
there should be no problems with exhaust valves. Why does the engine
need work already?

Dan


Bottom ends on those engines are usually good for 2,000 hours. The tops
start going at 500. Same for any of the small Continental engines and the
O-300. The jugs just don't last.

$500 is a good investment in exhaust valves. After 500 hours they start to
neck down. They aren't sodium-filled like Lycoming exhaust valves, but of
course they don't run as hot either.

I have seen a few of these Continental jugs last as much as 800 hours, but
they are the exception, not the rule.

Now watch and see if someone doesn't jump in here claiming a thousand hours,
and counting, on his cylinders.

OK, I'll do it. I had over a thousand (maybe 1200STOH) on the C-85 in
my old Chief. Never been majored and when I sold it, it had 2400TT.
Compressions were in the 75 and above range. Used a quart in 14-16
hours. Since the top, it had used Shell 15W-50 semi-synthetic oil. Of
course, I'm not claiming there couldn't have been worn parts (valves
etc.) but it sure ran sweet and strong.

On the other hand, I have to tear down my A-65 since I have (suspect at
this point) a burned valve from 100LL use I imagine (cross country
to/from Oshkosh last year and that was all that was available). It has
about 850 SMOH. Since I have one dead one, I will pull all 4 and put in
100 Octane valves since I don't think 80 is coming back...

Scott


jls wrote:
wrote in message
oups.com...

Only 650TT? Unless there's serious corrosion or a burnt valve,
there should be no problems with exhaust valves. Why does the engine
need work already?

Dan



Bottom ends on those engines are usually good for 2,000 hours. The tops
start going at 500. Same for any of the small Continental engines and the
O-300. The jugs just don't last.

$500 is a good investment in exhaust valves. After 500 hours they start to
neck down. They aren't sodium-filled like Lycoming exhaust valves, but of
course they don't run as hot either.

I have seen a few of these Continental jugs last as much as 800 hours, but
they are the exception, not the rule.

Now watch and see if someone doesn't jump in here claiming a thousand hours,
and counting, on his cylinders.

"Scott" wrote in message
...
OK, I'll do it. I had over a thousand (maybe 1200STOH) on the C-85 in
my old Chief. Never been majored and when I sold it, it had 2400TT.
Compressions were in the 75 and above range. Used a quart in 14-16
hours. Since the top, it had used Shell 15W-50 semi-synthetic oil. Of
course, I'm not claiming there couldn't have been worn parts (valves
etc.) but it sure ran sweet and strong.

Scott, you are a combination of special, astute, and lucky. Good for you.

On the other hand, I have to tear down my A-65 since I have (suspect at
this point) a burned valve from 100LL use I imagine (cross country
to/from Oshkosh last year and that was all that was available). It has
about 850 SMOH. Since I have one dead one, I will pull all 4 and put in
100 Octane valves since I don't think 80 is coming back...

I flew into a rural sod field on the Nolichucky River and coaxed a friendly
farmer to take me to a local Amoco station for gasoline --- So's I could
avoid that dreadful 100LL from the county airport. There weren't any
gasoline cans there but a darling waitress at the greasy spoon next door
washed out two flat and flexible 5-gallon cooking oil containers for me.
That 87 octane got me and the little A-65 home. If you're stuck with the
deplorable tankful of 100LL, MMO helps.

I had a burnt valve on a low-time A-65 once. I changed out the rocker arm
because it looked like the toe was pushing the stem eccentric in the guide.
I lapped in a new valve and it worked and has kept good compression now for
more than 200 hours.

Scott


jls wrote:
wrote in message
oups.com...

Only 650TT? Unless there's serious corrosion or a burnt valve,
there should be no problems with exhaust valves. Why does the engine
need work already?

Dan



Bottom ends on those engines are usually good for 2,000 hours. The
tops
start going at 500. Same for any of the small Continental engines and
the
O-300. The jugs just don't last.

$500 is a good investment in exhaust valves. After 500 hours they
start to
neck down. They aren't sodium-filled like Lycoming exhaust valves,
but of
course they don't run as hot either.

I have seen a few of these Continental jugs last as much as 800 hours,
but
they are the exception, not the rule.

Now watch and see if someone doesn't jump in here claiming a thousand
hours,
and counting, on his cylinders.