 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
Hopperdhh(at)aol.com
Guest
|
 Posted: Fri Jun 01, 2007 2:34 am Post subject: RV-7 engine/prop options |
 |
|
I wrote this some time ago and it never was posted. Here it is now for what its worth!
Some engine building thoughts:
I agree with Stein here -- go get an overhaul manual (and the parts catalog) and do it yourself. Send the parts out and get everything yellow tagged, install new parts where recommended, and save all the tags and receipts in a folder. After all, a Lycoming is a just a 4 cylinder version of a Briggs & Stratton. Well, it turns out that it is not quite that simple, but still there is usually only one way that the parts will fit. In a way its like building the rest of the airplane. There is help available on this list or on the Matronics engine list. Just take your time at each step and get it right. If there is any doubt, stop and get advice. The manuals are pretty thorough. One exception is that there are some bolt torques that are not called out that should be. I'm thinking here of the bolts that hold the idler shafts to the case. Using the recommended torque for that size bolt will strip the threads in the case. (How do I know that?)
The ONLY way you are going to know what is in your engine is to put it together yourself. You will find that you will have to make some compromises -- nothing is perfect. For example, I try my best to make sure the pieces in my engine are matched for balance, but they never come out exact. (I haven't yet reached the point of being able to balance connecting rods, so I must choose from what is available. I don't trust the local hot rod shops to appreciate the stresses in a 2700 RPM Lyc. Or to fully appreciate the fact that lives could be at stake if one should fail. These rods are harder to balance because they do not have extra weight at each end for balancing purposes like auto engine rods.) Here is a case where Lycoming has a pretty wide window, but the engine will run with less vibration if the rods (and pistons) are matched. In my case, I put the closest pair in the rear of the engine with hopes that balancing the prop will correct the front pair. If they are too far apart, I get more rods and choose a closer pair. This gets expensive. Economics forces some compromises. There is no way around it. There is no perfect engine. The clearances are often not exactly where you'd like them to be. There is usually a pretty wide tolerance band, but you don't want to be too close to either end of it. I wonder if all builders check the dry lifter clearance. I had to order new pushrods to get all of them in tolerance. Once you have decided that its good enough, you have to live with it. Believe me, you will care more about how well your engine is put together than anyone else who might put it together for you.
Just because someone builds airboat engines doesn't mean they don't know what they're doing. I'm sure there are some good ones out there. I think Stein was speaking in terms of probability. On the other hand just because someone has a fancy shop that builds only aircraft engines doesn't mean that they always do it right either, or that they are as particular as they ought to be. They run into compromising choices that they have to make every day. Hopefully, their experience has taught them how to make those choices. Its a matter of knowing and doing what is right -- its a matter of integrity.
After a prop strike I personally disassembled my engine (which was put together by a reputable shop) and found a few things that really disappointed me. Here are some examples:
1. Rod nuts were not a matched set. Some looked more oil stained than others. Some were different styles than the several sets that I have bought. I'm not sure if they were for an IO-360, or not. They probably were not new when the engine was overhauled. This makes me wonder about the stretch type rod bolts -- very critical parts in a 200 HP IO-360. These must be replaced at overhaul.
2. Genuine silk thread was not used to seal the case halves. Cotton (or synthetic) thread was used and it fell apart when the case was separated. I could pick up a piece of the thread and pull it apart with my fingers. If it were silk, I couldn't do that. The pattern it left showed that part of it was not on the surface of the case, but had fallen inside the engine during assembly. The engine had a pesky oil leak in that area -- this could well have been the cause.
3. The engine always vibrated more than I thought it should. Dynamically balancing the prop didn't help. This could have been due to rod weight mismatch or it could have been the prop -- no way to tell now. When I installed the engine I assembled, the vibration was noticeably better, but it is not the same prop. I took out a counterweighted IO-360 engine (-C1E6) and installed one without the counter weights (-A1A). I am now assembling the original counterweighted engine with a new crank. (Read ahead and this will make more sense.)
4. Would you believe the engine had a left turning crank in it? Yes, it did. I have mentioned this on this list before. This puts the oil holes in a less than optimum position for oiling the rod bearings when it is used in a normal turning engine. In fact, it puts them in about the worst location. Some say this will work OK, some say it will eat up the rod bearings. I only had about 160 hours on the engine and the bearings didn't look too bad, but who knows? I couldn't live with myself if I put it back it my own plane, let alone someone else's. The FAA is looking in to this one.
If you have never done this kind of work before, maybe you would be better off having someone else do it for you. Experience is a good teacher, but it can be an expensive way to learn things! I can't wholeheartedly suggest that everyone should build their own engine. It is really stressful. There is a lot to worry about -- at least it causes me a lot of worry. But after I have it done, I have pretty high confidence that it is going to serve me well. I don't have a lot of experience with aircraft engines. Most of my engine building experience was in the circle track racing business. And that was only building engines for my own car. If I didn't have that experience, I don't know if I would have the confidence to attempt an engine for my airplane. I built my race engines because I couldn't afford to buy as good of engine as I could build, so it made economic sense at the time. BTW this was quite some time ago!
Well, there's some of my thoughts on engine assembly. I'm sure not everyone will agree with what I've written, so I'll go look for my old Nomex underwear!
Best regards,
Dan Hopper
RV-7A
In a message dated 4/24/2007 12:26:57 AM Eastern Standard Time, stein(at)steinair.com writes:
| Quote: | --> RV-List message posted by: "Stein Bruch" <stein(at)steinair.com>
Why not do it yourself? It's not difficult or hard, nor requires many
special tools. Buy the overhaul manual, buy the parts and "get 'er done"!
One thing I would stay away from is several of the airboat builders - don't
know specifically names, but I've seen plenty of their "handiwork" and have
not yet been overly impressed. One such engine just cost one of my
employees BIG TIME in $$'s and pain in the rear. Engine was "new" by an
airboat builder. I have the remains on the floor of my shop. Not just
substandard, but downright scary (mismatched rods, butchered crank,
mismatched cyliners, mismatched pistons, the list goes on and on). |
See what's free at AOL.com.
[quote][b]
| | - The Matronics RV-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?RV-List |
|
|
|
| Back to top |
|
 |
bmeyette
Joined: 14 Mar 2007
Posts: 72
Location: Cornish, NH
|
| Posted: Fri Jun 01, 2007 1:44 pm Post subject: RV-7 engine/prop options |
|
|
There’s a page on my web site with lots of pics & details of how to build your own Lycoming. Be clean & be careful & should be no problem
<![if !supportEmptyParas]> <![endif]>
http://brian76.mystarband.net/SuperiorTextPics.htm
<![if !supportEmptyParas]> <![endif]>
brian
<![if !supportEmptyParas]> <![endif]>
<![if !supportEmptyParas]> <![endif]>
<![if !supportEmptyParas]> <![endif]>
--
| | - The Matronics RV-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?RV-List |
|
_________________
Brian Meyette, Cornish, NH
RV-7A QB tipup, supercharged Subaru STi engine, MT CS prop, all glass day/night/IFR panel, being built with solar and wind power
N432MM
http://brian76.mystarband.net/RV-7Ahome.htm |
|
| Back to top |
|
|
ceengland(at)bellsouth.ne
Guest
|
| Posted: Sun Jun 03, 2007 5:55 am Post subject: RV-7 engine/prop options |
|
|
Hi Dennis,
Thanks for reposting so we can read about your experience. Your
experience really isn't all that rare, & that's what drove my original
question. It seems obvious to me that integrity & competence are far
more important than an A&P ticket if you want a good engine build.
I'm not afraid of building my own but I am a bit leery of buying a core
that costs as much as a typical auto conversion & then risk having to
buy something major like a crankshaft, pushing costs into the realm of a
new clone engine.
My original question was asked in the hope of finding people who have
had experience with 'alternative' (airboat) engine builders. It's
interesting that we've seen one 1st hand report of an airboat engine
disaster and one 1st hand account of a 'traditional' build disaster. In
addition, I also got a private email from someone who had a major
problem with one of the premier build shops that may end up in
litigation because they have not been responsive. Three 1st hand
accounts is much too small a sample size; I was hoping for more
response. Perhaps those who have been willing to 'go there' don't bother
with this list. 
Thanks,
Charlie
Hopperdhh(at)aol.com wrote:
| Quote: | I wrote this some time ago and it never was posted. Here it is now for
what its worth!
Some engine building thoughts:
I agree with Stein here -- go get an overhaul manual (and the parts
catalog) and do it yourself. Send the parts out and get everything
yellow tagged, install new parts where recommended, and save all the
tags and receipts in a folder. After all, a Lycoming is a just a 4
cylinder version of a Briggs & Stratton. Well, it turns out that it is
not quite that simple, but still there is usually only one way that the
parts will fit. In a way its like building the rest of the airplane.
There is help available on this list or on the Matronics engine list.
Just take your time at each step and get it right. If there is any
doubt, stop and get advice. The manuals are pretty thorough. One
exception is that there are some bolt torques that are not called out
that should be. I'm thinking here of the bolts that hold the idler
shafts to the case. Using the recommended torque for that size bolt
will strip the threads in the case. (How do I know that?)
The ONLY way you are going to know what is in your engine is to put it
together yourself. You will find that you will have to make some
compromises -- nothing is perfect. For example, I try my best to make
sure the pieces in my engine are matched for balance, but they never
come out exact. (I haven't yet reached the point of being able to
balance connecting rods, so I must choose from what is available. I
don't trust the local hot rod shops to appreciate the stresses in a 2700
RPM Lyc. Or to fully appreciate the fact that lives could be at stake
if one should fail. These rods are harder to balance because they do
not have extra weight at each end for balancing purposes like auto
engine rods.) Here is a case where Lycoming has a pretty wide window,
but the engine will run with less vibration if the rods (and pistons)
are matched. In my case, I put the closest pair in the rear of the
engine with hopes that balancing the prop will correct the front pair.
If they are too far apart, I get more rods and choose a closer pair.
This gets expensive. Economics forces some compromises. There is no
way around it. There is no perfect engine. The clearances are often
not exactly where you'd like them to be. There is usually a pretty wide
tolerance band, but you don't want to be too close to either end of it.
I wonder if all builders check the dry lifter clearance. I had to order
new pushrods to get all of them in tolerance. Once you have decided
that its good enough, you have to live with it. Believe me, you will
care more about how well your engine is put together than anyone else
who might put it together for you.
Just because someone builds airboat engines doesn't mean they don't know
what they're doing. I'm sure there are some good ones out there. I
think Stein was speaking in terms of probability. On the other hand
just because someone has a fancy shop that builds only aircraft engines
doesn't mean that they always do it right either, or that they are as
particular as they ought to be. They run into compromising choices that
they have to make every day. Hopefully, their experience has taught
them how to make those choices. Its a matter of knowing and doing what
is right -- its a matter of integrity.
After a prop strike I personally disassembled my engine (which was put
together by a reputable shop) and found a few things that really
disappointed me. Here are some examples:
1. Rod nuts were not a matched set. Some looked more oil stained than
others. Some were different styles than the several sets that I have
bought. I'm not sure if they were for an IO-360, or not. They probably
were not new when the engine was overhauled. This makes me wonder about
the stretch type rod bolts -- very critical parts in a 200 HP IO-360.
These must be replaced at overhaul.
2. Genuine silk thread was not used to seal the case halves. Cotton
(or synthetic) thread was used and it fell apart when the case was
separated. I could pick up a piece of the thread and pull it apart with
my fingers. If it were silk, I couldn't do that. The pattern it left
showed that part of it was not on the surface of the case, but had
fallen inside the engine during assembly. The engine had a pesky oil
leak in that area -- this could well have been the cause.
3. The engine always vibrated more than I thought it should.
Dynamically balancing the prop didn't help. This could have been due to
rod weight mismatch or it could have been the prop -- no way to tell
now. When I installed the engine I assembled, the vibration was
noticeably better, but it is not the same prop. I took out a
counterweighted IO-360 engine (-C1E6) and installed one without the
counter weights (-A1A). I am now assembling the original
counterweighted engine with a new crank. (Read ahead and this will make
more sense.)
4. Would you believe the engine had a left turning crank in it? Yes,
it did. I have mentioned this on this list before. This puts the oil
holes in a less than optimum position for oiling the rod bearings when
it is used in a normal turning engine. In fact, it puts them in about
the worst location. Some say this will work OK, some say it will eat up
the rod bearings. I only had about 160 hours on the engine and the
bearings didn't look too bad, but who knows? I couldn't live with
myself if I put it back it my own plane, let alone someone else's. The
FAA is looking in to this one.
If you have never done this kind of work before, maybe you would be
better off having someone else do it for you. Experience is a good
teacher, but it can be an expensive way to learn things! I can't
wholeheartedly suggest that everyone should build their own engine. It
is really stressful. There is a lot to worry about -- at least it
causes me a lot of worry. But after I have it done, I have pretty high
confidence that it is going to serve me well. I don't have a lot of
experience with aircraft engines. Most of my engine building
experience was in the circle track racing business. And that was only
building engines for my own car. If I didn't have that experience, I
don't know if I would have the confidence to attempt an engine for my
airplane. I built my race engines because I couldn't afford to buy as
good of engine as I could build, so it made economic sense at the time.
BTW this was quite some time ago!
Well, there's some of my thoughts on engine assembly. I'm sure not
everyone will agree with what I've written, so I'll go look for my old
Nomex underwear!
Best regards,
Dan Hopper
RV-7A
In a message dated 4/24/2007 12:26:57 AM Eastern Standard Time,
stein(at)steinair.com writes:
Why not do it yourself? It's not difficult or hard, nor requires many
special tools. Buy the overhaul manual, buy the parts and "get 'er
done"!
One thing I would stay away from is several of the airboat builders
- don't
know specifically names, but I've seen plenty of their "handiwork"
and have
not yet been overly impressed. One such engine just cost one of my
employees BIG TIME in $$'s and pain in the rear. Engine was "new" by an
airboat builder. I have the remains on the floor of my shop. Not just
substandard, but downright scary (mismatched rods, butchered crank,
mismatched cyliners, mismatched pistons, the list goes on and on).
|
| | - The Matronics RV-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?RV-List |
|
|
|
| Back to top |
|
|
pitts_pilot(at)bellsouth.
Guest
|
| Posted: Sun Jun 03, 2007 12:00 pm Post subject: RV-7 engine/prop options |
|
|
Charlie England wrote:
| Quote: |
Hi Dennis,
Thanks for reposting so we can read about your experience. Your
experience really isn't all that rare, & that's what drove my original
question. It seems obvious to me that integrity & competence are far
more important than an A&P ticket if you want a good engine build.
I'm not afraid of building my own but I am a bit leery of buying a
core that costs as much as a typical auto conversion & then risk
having to buy something major like a crankshaft, pushing costs into
the realm of a new clone engine.
|
You might make that a condition of the sale. But then litigation is a
nasty way to spend your time. Maybe a non-refundable deposit may make
the difference. It's a gamble on both ends. The seller may not know
the engine (or parts) is crap.
| Quote: | My original question was asked in the hope of finding people who have
had experience with 'alternative' (airboat) engine builders.
|
I bought an airboat engine ..... that was built up from different case
halves. Sold it off as parts to another airboat engine builder. I
could have sent the case out and had it overhauled, but I didn't want to
take the chance. It wasn't a total disaster since I got all my money back.
| Quote: | It's interesting that we've seen one 1st hand report of an airboat
engine disaster and one 1st hand account of a 'traditional' build
disaster. In addition, I also got a private email from someone who had
a major problem with one of the premier build shops that may end up in
litigation because they have not been responsive. Three 1st hand
accounts is much too small a sample size; I was hoping for more
response. Perhaps those who have been willing to 'go there' don't
bother with this list.
|
If you have a way to verify it's 'history', I'd be more inclined to
purchase a core. I have (right now) an O-320 and IO-470 that I bought
to rebuild. $3500 and $4000 respectively. The accessories will be
worth most of the cost!!!.
Linn
| | - The Matronics RV-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?RV-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
