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Franklin Leaning Techniques

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Jerrid Stottlemyre
(@tr57gwyyahoo-com)
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I'm not trying to spark the lean of rich debate here, but thought I might reach out for any tips and techniques for leaning the Franklin. I have an EGT gauge which I've been using at cruise. The CFI that gave me my checkout recommended I don't mess with the mixture for taxi and lower altitudes, but I've been getting a little bit of spark plug fouling so I started leaning all the time and for taxi. She leans almost to cut off for taxi.

 
Posted : 06/08/2020 2:40 am
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Michael
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 I lived with a 150 Franklin for 35 years in a Bellanca Cruisair. Leaning on the ground is one thing but at cruise you will burn up the valves, seats, guides, the whole works if you are aggressive with the EGT. Fouled plugs are a problem you have to live with using 100LL

 
Posted : 06/08/2020 7:39 pm
Dennis Crenshaw
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I don't have an EGT but I have always leaned to maximum rpm (easy with a digital or portable optical tach) an then enrichen about 1/2 in. with the mixture control.  A single EGT is not telling you much because you don't know if it's on the leanest cylinder.  Watch Mike Busch's you tube video on leaning simple carbureted, fixed pitch propeller engines.  https://www.youtube.com/watch?v=_VfiPuheeGw .  Lean aggressively on the ground to avoid plug fouling, and avoid prolong idling.  I always lean in the air.  If it's 100 deg. on the ramp then I'd lean even at my low local cruise altitudes of typically 2000 ft. agl.  In the wintertime the air is much more dense so you won't need to lean as much.  Anyway, that's my technique, for what it's worth.

 
Posted : 07/08/2020 1:15 am
Jerrid Stottlemyre
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@dcn6102m Great video. Very thorough. I guess the root of my question, though, is does the Franklin in particular have any personality differences (when it comes to leaning) that differs from the traditional Lycos and Connies?

Second question (Maybe off topic): My 108 has a manifold pressure gauge, which is something I've never seen on a constant pitch prop. Should I be using that for something? Does that play into the leaning game as well?

 
Posted : 07/08/2020 6:01 am
Dennis Crenshaw
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@tr57gwyyahoo-com  No differences that I am aware of.   Some engines have poorer fuel distribution than others.  I've heard the Conti O-470 typically has poor fuel distribution.   I think a lot of the Stinson old timers will tell you to lean until the engine starts to run rough, and then enrichen.  I believe that's what the owner's operating manual also recommends.  After watching Mike Busch's video again, I see where leaning to best power is still too rich, so my technique more than likely is running the engine too rich.  I can't see where an MAP gauge is of much use on a fixed pitch propeller engine.

 
Posted : 07/08/2020 5:34 pm
Michael
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A big difference is the metal in the valves, seats and guides. OEM exhaust valves for the 150 are hard to come by. I had to have new valves made. The guides are cheap cast iron. You can use the manifold pressure gauge to get peak power not the EGT. It's not worth it to lean  an old Franklin 150 very much.

 
Posted : 08/08/2020 8:28 pm
Jerrid Stottlemyre
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@ecos36gmail-com Thats a good point. Gives the manifold pressure a purpose. Is this specific to the 150? I have a 165. (Not that part availability is a good reason to burn up valves)

 
Posted : 09/08/2020 4:17 pm
Michael
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 Don't know anything about a 165. There must be a source for the exh valves. Wonder if they put 165 valves in a 150 these days.?

 
Posted : 09/08/2020 5:12 pm
Jerrid Stottlemyre
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@ecos36gmail-com Not sure. I know the engines are very close to one another (same displacement, and same in a lot of other ways). One big difference is the lifter (valve) covers are different. The 165 needed to have more clearance for the lifters (You can use a 165 cover on a 150, but not the other way around). I'm not sure if the valves are different, but they might be based on this.

 
Posted : 12/08/2020 7:22 am
lawheelock
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Posted by: @tr57gwyyahoo-com

@ecos36gmail-com Not sure. I know the engines are very close to one another (same displacement, and same in a lot of other ways). One big difference is the lifter (valve) covers are different. The 165 needed to have more clearance for the lifters (You can use a 165 cover on a 150, but not the other way around). I'm not sure if the valves are different, but they might be based on this.

165 valves are longer than 150 valves for the higher lift cam. They also have a different stem diameter.  Rocker arms are the same, but the rocker supports are higher above the head.  Both 150 and 165 are best with the non-cast iron valve guides (bronze alloy or something) that are more recently supplied as they don't rust from in-activity. The cast iron guides are more wear resistant but one has to fly the engine often and never let it sit for months or the valves will rust weld to the cast iron guides.  Bad news. 

Leaning to roughness and then enrichen some is the best technique on either engine. 150 or 165.

Sodium cooled helicopter valves are legal in the 165 as they are the same dimensions as the stock 165 valves.  They probably last longer than the stock valves when forced to use 100LL. 

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer

 
Posted : 18/08/2020 12:07 am
Jerrid Stottlemyre
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@lawheelock Thanks Larry. Did I hear that you're based out of Harlingen? What a shame I didn't get interested in the 108 sooner. I lived in Corpus Christi from Feb 2016-May 2019 and flew out/in to Harlingen weekly in a T-6B. Would've been great to shoot the shit and pick your brain about Stinson's. I now own a -2 in San Diego.

 
Posted : 18/08/2020 5:46 am
lawheelock
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Posted by: @tr57gwyyahoo-com

@lawheelock Thanks Larry. Did I hear that you're based out of Harlingen? What a shame I didn't get interested in the 108 sooner. I lived in Corpus Christi from Feb 2016-May 2019 and flew out/in to Harlingen weekly in a T-6B. Would've been great to shoot the shit and pick your brain about Stinson's. I now own a -2 in San Diego.

Jerrid,

No, not Harlingen, 20 miles north.  I own what was then Bell airfield, now Flying W Airport,  2 miles south of Raymondviloe .  Designator XS56 adjacent to and just west of Business 77 on FM 490.  I assume you are either Navy or Coast Guard?  Yes, I have been here from usually Nov to June for the last more than 20 years, but still here this year due to working on a -1 through June then the virus and now damage from Hurricane Hanna, and also some recent health problems.  I put a Lycoming O-360 in my 108 in 2012.  Climbs better, takeoff better, but no faster. I have owned and flown and maintained the 108 for more than 52 years I was a civilian engineer for the Navy back years ago and have visited the Coronodo Seal Team base in the '60s or early '70s.  Have been to many Navy bases but never Corpus. Also, flew the Stinson into Lindberg field IFR in the '80s and flew over El Centro at 10,000' and looked down on the Blue Angels practicing on that trip.

Larry, N584LW

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer

 
Posted : 18/08/2020 4:16 pm
Jerrid Stottlemyre
(@tr57gwyyahoo-com)
Posts: 25
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@lawheelock I was a Navy Primary Instructor in Corpus flying the T-6B. I bet I flew over your house a hundred times. I'm at NAS North Island now.

 
Posted : 18/08/2020 10:21 pm
Michael
(@ecos36gmail-com)
Posts: 295
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150 hp exhaust valves.  It would be cool if an engine ovhl guy could chime in. 

The exh valve stem is smaller at the retainer end! What you do is, buy an exh valve from an automotive standard parts catalog that has the correct head and stem diameter and a stem that is long enough to re- work. Then you send the valves off to a fancy machine shop that can grind down the stem end for the retainer. It's called centerless grinding. Then you need to machine a groove for the retainer. Then you need to hard coat the end! The guy who does all should be a friend.

 
Posted : 19/08/2020 12:59 am
lawheelock
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@ecos36gmail-com

Michael,

The stock 165 valves use the same retainers as the 150 valves.  But, the sodium cooled helicopter valves that fit the 165 use a different type retainer with a rotating cap so that they rotate.  The retainers for that valve setup are different than the stock, non rotating 165 valves.  True, that 165 valves have a different stem diameter than 150s but the head and stock retainers are the same.

Larry Wheelock, A&P/IAStinson 108 N584LW 180 LycTexas in Winter; Indiana in Summer

 
Posted : 19/08/2020 1:06 am
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