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andy(at)suncoastjabiru.co
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 Posted: Wed May 09, 2007 6:03 am Post subject: [ Bob Haas ] : New Email List Photo Share Available! |
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Hello Lynn,
I'm (also) unaware of any particular wear issue with rocker shafts or rocker
bushings but admittedly where I'd done 'early' top-overhauls due to head
overheating or other issues I have noticed wear on the rocker shafts and
have replaced the affected ones along with the respective rocker bushings.
With the head off it's an easy and therefore inexpensive job. From memory,
I've done this with heads at 350 hours onwards, but I hasten to add not on
all heads. Some at much higher times have been OK.
In looking for a cause of higher-than-normal wear, we should consider the
following:
1. Oil feed integrity; meaning that a blockage in any part of the oil feed
line to the valve gear will compromise lubrication. If you get the usual
'teaspoon' of oil come out of the valve chamber when you take the cover off,
your lubrication is probably OK. The oil-way from the feed into the chamber
is a small slot right above each valve spring and you can check these by
sticking a piece of (e.g.) locking wire in there and checking for an
obstruction.
2. The rocker shafts are lubricated by splash from the valve chamber and
there should be (depending on serial number) an oil hole in the rocker which
you can check for obstructions. I don't have my dealer tech. info book with
me right now (you find me in UK for a week or two) so I'm going from memory
and there have been changes in rocker design, offset, gearing, etc over the
years.
Hope this helps - let me know if not.
Andy
Suncoast Sportplanes, Inc.
39248 South Ave, Zephyrhills, FL 33542
Tel: (813) 779 2324 Fax: (813) 779 2246
www.suncoastjabiru.com
--
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Wed May 09, 2007 8:58 am Post subject: [ Bob Haas ] : New Email List Photo Share Available! |
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Hi Andy-
Hope things are going well in the UK (I spoke with Dave A. at your
place yesterday).
1. I've always had the teaspoon of oil...maybe a little
less...when removing covers, but this time I got some brass
particles. That prompted the shaft removal, and subsequent bushing
wear discovery. Jim at Pacific Jab suggested drilling the hole in the
delivery tube fitting *one* decimal-size drill larger, which I did,
going from the (found).059" to .063". I've ordered brass bushings of
the oil-retention type as replacement bushings for the teflon coated
that are presently in my engine (Serial #2062). I blew through the
rubber tee fitting while I had the delivery tube removed, and all
lines to above the valves are clear.
2. My rockers had no oil hole in them until I decided that there
was a need for one, so I drilled a hole in each one, which will allow
splash oil to feed the bushing. This hole is vertical to the position
of the rocker, and will allow the oil to enter the rocker at the
point where there is no load between the shaft and the rocker arm.
Thanks for the reply Andy, and I'll keep the group posted. By the
way, did you get the pictures of my distributor shaft problem? I sent
them to you, Pete, and Jim.
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/275+ hrs
On May 9, 2007, at 10:02 AM, Andy Silvester wrote:
[quote]
<andy(at)suncoastjabiru.com>
Hello Lynn,
I'm (also) unaware of any particular wear issue with rocker shafts
or rocker
bushings but admittedly where I'd done 'early' top-overhauls due to
head
overheating or other issues I have noticed wear on the rocker
shafts and
have replaced the affected ones along with the respective rocker
bushings.
With the head off it's an easy and therefore inexpensive job. From
memory,
I've done this with heads at 350 hours onwards, but I hasten to add
not on
all heads. Some at much higher times have been OK.
In looking for a cause of higher-than-normal wear, we should
consider the
following:
1. Oil feed integrity; meaning that a blockage in any part of the
oil feed
line to the valve gear will compromise lubrication. If you get the
usual
'teaspoon' of oil come out of the valve chamber when you take the
cover off,
your lubrication is probably OK. The oil-way from the feed into the
chamber
is a small slot right above each valve spring and you can check
these by
sticking a piece of (e.g.) locking wire in there and checking for an
obstruction.
2. The rocker shafts are lubricated by splash from the valve
chamber and
there should be (depending on serial number) an oil hole in the
rocker which
you can check for obstructions. I don't have my dealer tech. info
book with
me right now (you find me in UK for a week or two) so I'm going
from memory
and there have been changes in rocker design, offset, gearing, etc
over the
years.
Hope this helps - let me know if not.
Andy
Suncoast Sportplanes, Inc.
39248 South Ave, Zephyrhills, FL 33542
Tel: (813) 779 2324 Fax: (813) 779 2246
www.suncoastjabiru.com
--
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?JabiruEngine-List |
|
_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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info(at)usjabiru.com
Guest
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| Posted: Wed May 09, 2007 11:44 am Post subject: [ Bob Haas ] : New Email List Photo Share Available! |
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Lynn,
I've been looking through past emails and do not see one from you with
photos of the rocker shaft or bushing.
Pete Krotje
Jabiru USA Sport Aircraft, LLC
--
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?JabiruEngine-List |
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Wed May 09, 2007 1:45 pm Post subject: [ Bob Haas ] : New Email List Photo Share Available! |
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I haven't sent them out yet, Pete, but I will. They will be via Kodak
EasyShare. I'll even send them to you, Andy and Jim separately, just
in case Kodak doesn't understand CC'ing.
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/275+ hrs
On May 9, 2007, at 3:44 PM, Jabiru USA wrote:
| Quote: |
<info(at)usjabiru.com>
Lynn,
I've been looking through past emails and do not see one from you with
photos of the rocker shaft or bushing.
Pete Krotje
Jabiru USA Sport Aircraft, LLC
|
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?JabiruEngine-List |
|
_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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