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02-19-2012, 08:39 PM
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Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
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Quote:
Originally Posted by Mel
I'm talking roller rocker arms.
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Who made them?
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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02-20-2012, 06:16 AM
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Join Date: Mar 2011
Location: fort worth,Texas
Posts: 22
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Lycoming Angle Valve Roller Rockers
I am currently dyno testing a roller rocker arm for angle valve lycoming engines. Will hopefully be through dyno in 30 to 60 days and be field testing. These will be aluminum with steel roller tip fully oiled. Ratio is 1.4 to one and will clear 10 to one pistons. They will require shorter pushrods (will be supplied in kit) and will be adjustable.
anticipate kit cost to be around 1800 for 4cylinder and 2500 for six cylinder.
Would appreciate feed back on interest.
Thanks
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02-20-2012, 07:04 AM
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Join Date: Mar 2005
Location: Dallas area
Posts: 10,768
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Quote:
Originally Posted by az_gila
Who made them?
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Ken Hatfield made them, but he's been out of business for quite some time.
They're made from billet aluminum with needle bearings.
__________________
Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
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02-21-2012, 07:55 AM
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Join Date: Jan 2005
Location: Round Rock, TX
Posts: 3,778
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Even running the Roller Rockers in the Lyco, we Cryo'ed all wear parts in the heads for long lasting durability. 
__________________
Reiley
Retired N622DR - Serial #V7A1467
VAF# 671
Repeat Offender / Race 007
Friend of the RV-1
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02-03-2016, 06:14 AM
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Join Date: Feb 2016
Location: Fayetteville, GA
Posts: 1
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Roller rockers
Hey RocketBob - I just had to pull a cylinder on my O-360 after 270 hours for a worn exhaust valve guide. ECI cylinders with the high chrome guides.
While you are correct (legally) that SB388C doesn't apply to ECI cylinders with high chrome guides, I find my guides wearing nevertheless.
Before I pulled the cylinder, I checked the guide with a dial bore gauge and found it worn only in the vertical axis i.e. oval shaped. Horizontally there was no measureable wear. It seems this could only have happened if the rocker was side loading the valve.
So, I'd be very much interested in roller rockers is anyone has a solution. In particular, I think steel is the way to go because of the potential for fatigue issues. Rockers go through stress cycles so fast that aluminum scares me in the long term...
For a good, simple reference on fatigue limits of aluminum vs. steel, check out this wiki -
https://en.wikipedia.org/wiki/Fatigue_limit
Anyone have a source for steel shaft type rockers for the O-360?
Thanks -
John
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02-03-2016, 07:40 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Welcome to VAF, John!
Are you sure you have enough oil flow up there? It is a tiny trade off corner with oil flow, coking on the stem, (sticking), wear, and valve rotation. It all comes down to being close to too hot. Positive valve rotators will be needed with roller tips. Good luck with the adventure.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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02-03-2016, 09:05 AM
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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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Welcome to VAF!
John, welcome aboard the good ship VAF 
__________________
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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02-03-2016, 10:43 AM
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Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
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It was my understanding from the automotive world that side loading was a product of poor geometry, not the interface method (i.e. proper geometry fixes side load regardless or roller or std interface). When I set up custom engines, I would use adjustable push rods to set the proper geometry of the valve train, then make pushrods based upon that desired length. Unfortunately this can only be done with adjustable rockers, which the Lycomings don't have.
You might be able to adjust geometry by swapping different rockers/pushrod combinations to get a desired outcome. I would expect that tolerances on rocker machining in the Lcoming's to be loose, but don't know that. I have never done geometry settings on standard rockers, so not sure on the correct measurement approach. It was easily done with sharpie marker with roller rockers.
Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
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02-03-2016, 11:00 AM
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Join Date: Sep 2014
Location: silverdale, WA
Posts: 208
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Ken Hatfield
roller rockers were troublesome, it seems. They were aluminum. If memory serves they were pulled from service due to fatigue failures. He offered some to me and I was tempted, but did not pull the trigger. Found out later that there were issues.... Mel, you may remember more about this.
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02-03-2016, 11:54 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by lr172
It was my understanding from the automotive world that side loading was a product of poor geometry, not the interface method (i.e. proper geometry fixes side load regardless or roller or std interface). When I set up custom engines, I would use adjustable push rods to set the proper geometry of the valve train, then make pushrods based upon that desired length. Unfortunately this can only be done with adjustable rockers, which the Lycomings don't have.
You might be able to adjust geometry by swapping different rockers/pushrod combinations to get a desired outcome. I would expect that tolerances on rocker machining in the Lcoming's to be loose, but don't know that. I have never done geometry settings on standard rockers, so not sure on the correct measurement approach. It was easily done with sharpie marker with roller rockers.
Larry
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Maybe more of the automotive issues were extra poor geometry, but there is no way around it, the valve moves linearly and the rocker tip moves in an arc about the pivot axis. They will slide and put a side force on the valve.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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