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12-15-2013, 09:28 AM
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Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
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Quote:
Originally Posted by az_gila
Why is the yellow type around the lower part of the cylinders only?
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Its in preparation for paint. The barrels are painted first. Then masked before assembly. Easier to put that on with the cylinders off.
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Kahuna
6A, S8 ,
Gold Hill, NC25
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12-18-2013, 02:34 PM
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Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
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Quote:
Originally Posted by Kahuna
While pulling off the exhaust, I noticed this warpiage located under the heat muff. Hidden for years. My muffs have never been off and I have had no reason to look under them. Hmmm. Whats that?
A quick call to Larry Vetterman... He has seen this before, although rarely. According to Larry, there are 2 cases where this is seen.
1. A wrapped exhaust, or ceramic coated exhaust. I have neither of these.
2. A muff exit blocked where the heat cant get away, either from a scat tube collapse or FW valve that does not dump overboard. Well I have never had either of those.
Either way, it is what it is. A tap with a punch to check wall thickness in the warpage area and Im satisfied that the warpage does not pose any risk so Im leaving it as is. Amazingly, the rest of the exhaust of completely great. I have never had a crack, support arm break, or anything of that nature in its years of service. Im cleaning it up and putting her back on.
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Decided to fix this pipe. Fixing this pipe was not difficult. Im fortunate to have friends and resources on the field here. My star smart guy is Mr. Gary Dehart, retired crew chief Hendrix Motorsports. If he cant do it, it cant be done. We set up a jig on his welding table, cut out the offending piece, & fitted in a new one. The joints are not straight by design. With 321 stainless, you also need very tight butt joints before committing rod to metal. Plus he is a perfectionists. I kept telling him we were not going to the moon here. But there is no convincing him that one day this exhaust might have to see duty on the space station or something. I love hanging out with Gary. I always am humbled and learn from the best. Thanks Gary for sharing your shop today.
During the welding process, a remote pressure argon feeder is installed into the pipe to force out air, and allow for a cleaner weld INSIDE and out.
In the end it looks like a simple straight pipe replacement.

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Kahuna
6A, S8 ,
Gold Hill, NC25
Last edited by Kahuna : 12-20-2013 at 06:04 AM.
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12-19-2013, 06:59 AM
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Join Date: Apr 2010
Location: Ridgeland, SC
Posts: 2,589
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Well its not everyone that has a neighbor like Gary Dehart, a Championship winning Crew Chief in the Cup series. I think its great that he was able and willing to help out. Yep---its cool to be able to watch and learn for masters like him!!!!!
Tom
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Tom Swearengen, TS Flightlines LLC, AS Flightlines
Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com, www.asflightlines.com
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12-19-2013, 08:05 AM
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Join Date: Feb 2006
Location: George West, TX
Posts: 567
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Quote:
Originally Posted by Kahuna
Decided to fix this pipe. Fixing this pipe was not difficult. Im fortunate to have friends and resources on the field here. My star smart guy is Mr. Gary Dehart, retired crew chief Hendrix Motorsports. If he cant do it, it cant be done. We set up a jig on his welding table, cut out the offending piece, & fitted in a new one. The joints are not straight by design. With stainless, you also need very tight butt joints before committing rod to metal. Plus he is a perfectionists. I kept telling him we were not going to the moon here. But there is no convincing him that one day this exhaust might have to see duty on the space station or something. I love hanging out with Gary. I always am humbled and learn from the best. Thanks Gary for sharing your shop today.
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His welding hood speaks volumes too. Me likee!!! 
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Deal Fair
RV-4 (N34CB)
George West, TX (8T6)
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12-19-2013, 08:39 AM
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Join Date: Feb 2005
Location: Sebring, FL
Posts: 14
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Case Dowels / Orings / Thru-Bolts
Quote:
Originally Posted by rocketbob
Actually this is an incorrect statement. The reason for the dowels are to bring those holes back up to size, not to prevent leaks. Actually adding a second path around the bushing increases the likelihood of a leak since now there are two paths for the oil to travel. They don't do that to make them stop leaking there. The o-ring counterbore mod is done to prevent leaks.
On the 540 there is an oversize thru bolt available so its just as good to ream the holes to .002 undersize for the larger thru bolt, and then you can counterbore for the o-ring.
So unless one could not ream to fit to size for an oversize thrubolt, I would not do this mod.
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I agree that the installation of the dowels is an approved repair for excessive wear at the thru bolt hole main bearing area. If the interference fit is diminished (Fretting occurs at the center mains) then thru bolts leak and a repair is required. As you suggest a basic mod is available (Lycoming) to improve leaking by only installing an oversized thru bolt and machining an o-ring groove in the case to fit around the thru bolt only. This repair is an approved fix that works for low horsepower engines but never holds up for long on higher horsepower engines.
In the past 30 years we found that with the installation of the center dowels and most important the addition of an o-ring groove around the dowel works best as a proper prevention and repair for case fretting. This improved modification results in improved leak prevention. These two Lycoming Service Instructions cover some of this information SI 1290 / SI 1123
I'm sure that opinions from engine builders may vary on this subject and no disrespect to rocket or his opinion/experience building engines..
Any questions jimmy@jbaircraftengines.com
__________________
Jimmy Brod
www.jbaircraftengines.com
Superior XP Engine sales / Custom Engine Overhaul / Redline Engines
863-655-5000 shop / 863-381-1530 cell
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12-19-2013, 09:05 AM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Not disagreeing but if it were my engine and the studs were necessary I would do both. That is, put the o-ring counterbore in along with the stud, and use a larger oring. On the high HP 540's usually at the third main where you see the most fretting/throughbolt hole wear, the others are usually fine.
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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12-27-2013, 03:28 PM
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Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
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Engine arrives
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Kahuna
6A, S8 ,
Gold Hill, NC25
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12-27-2013, 03:54 PM
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Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
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Heat mod
During my original build, I came up with the idea to pick up the fresh air for the heat muffs from the intercylinder baffles below the cylinders. I had a few things in mind with this.
1. Big engine, more heat, no change in inlet sq inches. I did not want to rob cold air off the rear baffles for heat.
2. Seemed like a good idea to pull heat from the warmer air that has already been warmed by the cylinder fins.
3. I could think of no downside.
This served me well over the years with plentiful heat even in sub zero conditions. The mod is pretty simple. Rivet a 2" flange to the intercylinder baffle and install. I could not reuse the ones from my lyco cylinders as the Titan tapered finned cylinders are a bit different. It does require some rebending of the valve cover drain lines that return oil back to the sump.
You will notice below that the cylinder wrap is safety wired to the cht probe insert on the right side of the picture. This is necessary since you cant tie the 2 wrappes together with that big 2" flange in the way. I had no problems with this in the first 2000 hours so I consider this a good working solution.
I forgot to take a picture of the final install but it looks just like my original one below.

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Kahuna
6A, S8 ,
Gold Hill, NC25
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12-27-2013, 04:12 PM
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Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
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Back in the air
After 5 days of work, plus stick in family time at xmas, my wonderful super 8 is back in the air. Everything fit back to where it was. I had one kinked oil line that Tom at TS Flightlines immediately rectified. Thanks Tom! Baffles are new. Geez I hate baffle work. Sealed up every nook and cranny with black RTV. Only issue I had on initial start was 2 plug wires reversed. I can live with that. Put 2 uneventful hours on her today. Fuel flow was a staggering 25gph.  I cant even look at it. Cool temps here kept cyl temps below 330. Thats pretty good given brand new cylinders.
This is what it looks like to break in an engine. Dizzy!
Everything works. Nothing to do now by fly it hard and fly it fast.
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Kahuna
6A, S8 ,
Gold Hill, NC25
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12-27-2013, 04:17 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Congratulations!
Mike, good job 
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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