o200a Overhaul and reaming new bushings

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Rob A

Filing Flight Plan
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Rob
Hi all,

I'm rebuilding an O200 for an experimental and need some help. I've pushed new bushings into the rocker arms and small end of the connecting rods that now must be reamed to size. Problem is I can't track down the recommended reamer according to the overhaul manual. I need a 0.6095" for the rocker arms and 0.9230" for the connecting rods. What is everyone doing to ream these parts? I know I could send them away to Aircraft Specialties but I kind of wanted to do as much as I can myself. I'm not too keen on using an adjustable reamer and would think that a piloted hand reamer is the way to go but I'm not an expert though and welcome recommendations.

thanks in advance!
Rob
 
I would let a reputable shop do it. Too much can go wrong reaming parts like this, doing it by hand is really not a great way to do it.
 
PaulS said:
I would let a reputable shop do it. Too much can go wrong reaming parts like this, doing it by hand is really not a great way to do it.
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An O-200 is dirt simple. If someone is comfortable with OHing an auto engine, the O-200 is a piece of cake.
 
Greg Bockelman said:
An O-200 is dirt simple. If someone is comfortable with OHing an auto engine, the O-200 is a piece of cake.
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It cost me almost nothing to have my rocker arms and conn rods cleaned, inspected, re-bushed, and yellow-tagged. I think the proper tools needed to do this correctly will be more expensive than having someone else do it. Unless you’re going to be doing a bunch of engines.....
 
Hi everyone and thanks for all the suggestions so far, keep them coming!

Those look like great reamers suggested above. All my google searching only came up with one that was close to the size I needed so those websites are helpful! I know I could have a reamer made to size but then the cost goes way up.

Yes an O200 is a simple engine, I don't plan on rebuilding it too often but I do like to try and do everything I can even if it costs a bit more. More satisfaction I find. I did add up the price if I were to get Aircraft Specialties to do the work and they want about $95 US per connecting rod and $32 per rocker arm. This will be over $500 plus the US to Canadian dollar exchange plus shipping will be almost $750 CAN. That's a few bucks for sure to press in a bushing and run a reamer through it. Plus I've already pressed in the bushings in everything myself. I see online the Harley Davidson folks have some really nice piloted or tapered hand reamers that they use for their rocker arms. I've also found lots of reamers for the intake and exhaust ports for both Continental and Lycoming. The O200 manual has the reamers recommended (Kent-Moore 5008 for rods and Kent-Moore 7232 for the rockers) but there is just no finding these tools anywhere. I even went to the Kent-Moore website and emailed them and they couldn't help. It really makes me wonder what airplane engine shops use. Do they just buy reamers or have them made or use some other way to ream it that I'm missing? Or perhaps use adjustable ones which isn't preferred I believe. I also called an auto rebuilding shop local to me and they said they thought they could do it in a lathe. He didn't sound too convincing and I really want a proper job. Does anyone have the name of a good shop to send too besides Aircraft Specialties? Greg where did you get yours done?


By the way here are the exact sizes from the manual:
- Rocker Arm bushing bore .6097 - .6107
- Conn. Rod Bushing Bore Bushings . Dia: .9230 - .9235

I would love to start posting my progress as I build for others to view and make recommendations as I go. So far I've had the case overhauled, the cam yellow tagged, new jugs and about ready to start putting it all together once I can get over this bushing reaming hurdle.

Rob,
 
Rob A said:
I can't track down the recommended reamer
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McFarlane Aviation and Aircraft Spruce sell specialized reamers. Don't know if they have what you need but might be able to point you in the right direction. However, I think you'll be a bit surprised at their cost. That is why most send out certain work to shops. Good luck.
 
Let'sgoflying! said:
Sometimes people just want to do stuff for the enjoyment of it.
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I'm pretty sure that the FAA has rules to prevent that.

You also have to consider the fact that we are talking about piston aircraft technology, much of which is straight out of 1940's Farmall tractors.
 
Again it's an engine for an amateur class aircraft (similar to the experimental in the US) which allows me complete such work. Not a certified aircraft.
 
Let'sgoflying! said:
I had no idea the FAA had rules that governed what Canadians did.
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While in the US, you bet they do.

I know, not the point, but I’m sure he just missed that.
 
I'm not an expert but I understand that in the US you are permitted to complete such work in the experimental class. I only know this because I follow a number of US builders (Zenith and Vans) who are doing their own rebuild. This is similar to that. Canadian amateur class aircraft are easily permitted in the US.

Either way this is off topic. I hope to hear from someone who has reamed their own bushings during a rebuild.

Perhaps I will end up sending them all off to get an "expert" do the work but I would prefer to do it myself and learn. And it's cheaper, but like my father used to say, "never feel sorry for a man who owns an airplane".


thanks all,
 
Rob A said:
I did add up the price if I were to get Aircraft Specialties to do the work and they want about $95 US per connecting rod.

I've also found lots of reamers for the intake and exhaust ports for both Continental and Lycoming.

Rob,
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Perhaps the $95 includes checking the rod for straightness and correcting it if necessary?

Port reamers?? Do you mean valve guide reamers?
 
flyingbrit said:
Perhaps the $95 includes checking the rod for straightness and correcting it if necessary?

Port reamers?? Do you mean valve guide reamers?
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It is to also check straightness but I've done that already.

And yes, it's valve guide reamers not port reamers. They are readily available.
 
Capt. Geoffrey Thorpe said:
https://www.aircraft-tool.com/shop/detail.aspx?id=PRO1 for the rockers?
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I've sent them an email asking if they carry the sizes I need. I do think that a piloted or slightly tapered reamer is better rather then a purely straight one to ensure it follows the bushing hole. Also if it was available as a hand reamer that would be ideal. I know the Harley guys have such things.. It just seems that there are tons of these engines with matching parts in other engine models so there should be readily available tools.
thanks again
 
Take it to an engine shop. Those bushings are more commonly sized using a rigid honing machine. It leaves a far better finish than a reamer and keeps the bore parallel to the bushing's OD. Reamers can scratch and wander off-center and leave an hourglass shape in the bore if one isn't really sharp with it. See this short video:


That machine is more complicated than it looks. It has a foot-operated pedal that engages the clutch (the motor is running to keep the coolant flowing, and the clutch allows gentle engagement) and also raises the stone in the mandrel. There is a dial gauge on the machine that shows how much the stone wedge is moving, and once a fellow figures out the stone loss per metal removed, he can get the job done quickly. The operator is gauging the bore on another gauge that isn't shown well at all in the video, and that gauge allows extrememly accurate sizing. The mandrel will follow the bushing bore, which has been machined at the same time as the OD and so is parallel. To get inaccuracy there would require the operator to be holding the work too far away from the mandrel, cocking it.

I have way too many hours of doing that.
 
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Dan Thomas said:
Take it to an engine shop. Those bushings are more commonly sized using a rigid honing machine. It leaves a far better finish than a reamer and keeps the bore parallel to the bushing's OD. Reamers can scratch and wander off-center and leave an hourglass shape in the bore if one isn't really sharp with it. See this short video:


That machine is more complicated than it looks. It has a foot-operated pedal that engages the clutch (the motor is running to keep the coolant flowing, and the clutch allows gentle engagement) and also raises the stone in the mandrel. There is a dial gauge on the machine that shows how much the stone wedge is moving, and once a fellow figures out the stone loss per metal removed, he can get the job done quickly. The operator is gauging the bore on another gauge that isn't shown well at all in the video, and that gauge allows extrememly accurate sizing. The mandrel will follow the bushing bore, which has been machined at the same time as the OD and so is parallel. To get inaccuracy there would require the operator to be holding the work too far away from the mandrel, cocking it.

I have way too many hours of doing that.
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This, really, read the third and forth sentences a couple times. And you really should check the holes after you ream or bore them, by the time you buy what you need to do it correctly it's cheaper to pay the shop.
 
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