July 5th 05, 02:08 PM
So I'm doing dry clearance on the lifters and one pushrod is jammed up
tight against the toe of the rocker arm, even with the lifter
collapsed.
Says the A&P/IA, "You didn't collapse the lifter."
"Oh, but yes, I did."
"How?"
"Stuck a toothpick up the hole and pushed the ball off its seat to git
the oil out."
So he runs a shim between the rocker arm toe and the valve stem and
leaves it there overnight. Next day, the same--- no dry clearance, no
lash----- and you need, by the A-65 rebuild manual, at least .030" and
no more than .110" dry clearance for the hydraulic lifter to do its
proper job. But this one cylinder on the exhaust valve side has none,
not even one thousandth.
So we send off for a shorter pushrod, but Othman at Triad says those
are not available, only longer ones are.
So then I go into the O-200 manual to see what they say, which is to
change out the valve and/or hydraulic lifter and/or pushrod and/or
cylinder. Somebody suggests grinding on the rocker toe, but there's a
reason for having all that brawn there on that toe with all the high
pressures needed to force an exhaust valve open against its two springs
about 600 times a minute.
Could this exhaust valve be stretched? Get out the mikes.
Well, it's the cylinder, we finally figured. At ECI they cratered the
valve seat so deep it seats too far down into the head. So the valve
stem sticks out too far from the guide and we got no dry clearance.
Matter of geometry.
Opposite of what a friend had with his Continental. The head
rebuilder he hired, just by eyeballing the stems, ground off too much
meat from the valve stems and my quietly disgruntled friend (who
loathes complaining) had to buy longer pushrods.
This expensive but, well, unusual cylinder purchased from ECI may
explain why that exhaust valve was sticking. The friendly Airframe and
Powerplant mechanic who put that engine together is gone now so I don't
fault him. Besides, he was just a prince of a fellow who would go
overboard with his generosity to help youngsters fly when they really
couldn't afford it. He trusted the cylinders to have been done
correctly, and 3 out of 4 were, except for the cermicrome.
Moral: Always check your dry clearance before putting that engine into
service. And be careful who you deal with when you buy cylinders. If
you can buy from somebody with moral character and a conscience, that's
helpful too, especially when you need after-purchase service.
I just bought 6 new Milleniums made by Superior -- from J&J in
Pleasanton, Texas, and they are performing like real troopers. I
noticed when I was sizing the rings that as they were pushed deeper
into the cylinders the spaces got smaller. And you know what?
Superior is putting a choke on those cylinders!
If I had it to do all over again I would have bought Continental
A-series cylinders from Superior, but they were not available then.
tight against the toe of the rocker arm, even with the lifter
collapsed.
Says the A&P/IA, "You didn't collapse the lifter."
"Oh, but yes, I did."
"How?"
"Stuck a toothpick up the hole and pushed the ball off its seat to git
the oil out."
So he runs a shim between the rocker arm toe and the valve stem and
leaves it there overnight. Next day, the same--- no dry clearance, no
lash----- and you need, by the A-65 rebuild manual, at least .030" and
no more than .110" dry clearance for the hydraulic lifter to do its
proper job. But this one cylinder on the exhaust valve side has none,
not even one thousandth.
So we send off for a shorter pushrod, but Othman at Triad says those
are not available, only longer ones are.
So then I go into the O-200 manual to see what they say, which is to
change out the valve and/or hydraulic lifter and/or pushrod and/or
cylinder. Somebody suggests grinding on the rocker toe, but there's a
reason for having all that brawn there on that toe with all the high
pressures needed to force an exhaust valve open against its two springs
about 600 times a minute.
Could this exhaust valve be stretched? Get out the mikes.
Well, it's the cylinder, we finally figured. At ECI they cratered the
valve seat so deep it seats too far down into the head. So the valve
stem sticks out too far from the guide and we got no dry clearance.
Matter of geometry.
Opposite of what a friend had with his Continental. The head
rebuilder he hired, just by eyeballing the stems, ground off too much
meat from the valve stems and my quietly disgruntled friend (who
loathes complaining) had to buy longer pushrods.
This expensive but, well, unusual cylinder purchased from ECI may
explain why that exhaust valve was sticking. The friendly Airframe and
Powerplant mechanic who put that engine together is gone now so I don't
fault him. Besides, he was just a prince of a fellow who would go
overboard with his generosity to help youngsters fly when they really
couldn't afford it. He trusted the cylinders to have been done
correctly, and 3 out of 4 were, except for the cermicrome.
Moral: Always check your dry clearance before putting that engine into
service. And be careful who you deal with when you buy cylinders. If
you can buy from somebody with moral character and a conscience, that's
helpful too, especially when you need after-purchase service.
I just bought 6 new Milleniums made by Superior -- from J&J in
Pleasanton, Texas, and they are performing like real troopers. I
noticed when I was sizing the rings that as they were pushed deeper
into the cylinders the spaces got smaller. And you know what?
Superior is putting a choke on those cylinders!
If I had it to do all over again I would have bought Continental
A-series cylinders from Superior, but they were not available then.