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exhaust bolt torque

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sarg314(at)comcast.net
Guest

Posted: Mon Jul 10, 2006 8:00 pm Post subject: exhaust bolt torque

I was going to torque down the nuts on the exhaust studs on my O-360 

when I noticed a contradiction between my torque tables and Larry 

Vetterman's instructions.  Larry says to torque the nuts to 100- 140 

in-lb.  That's the torque value for a 5/16-24 bolt, according to my 

table.  But the exhaust studs in my engine are 5/16-18.  The torque 

table says to use 80-90 in-lb for the coarse thread 5/16 bolts. 



What's the right torque value here?



Is this another situation like the engine case bolts (1/4-20) which are 

torqued at 90 - 100 in-lb (about double the value listed in the table)?



--

Tom Sargent, RV-6A

Vanremog(at)aol.com
Guest

Posted: Mon Jul 10, 2006 8:15 pm Post subject: exhaust bolt torque

In a message dated 7/10/2006 9:02:38 P.M. Pacific Daylight Time,  sarg314(at)comcast.net writes:

  	  Quote: 	
		  I    noticed a contradiction between my torque tables and Larry 

Vetterman's    instructions.  Larry says to torque the nuts to 100- 140 

in-lb.     That's the torque value for a 5/16-24 bolt, according to my  

table. 	


 

 =========================================

  

 I torqued them to 100-140 in-lb just as Larry indicates.   He's the exhaust expert as far as I'm concerned!

  

  

  

 GV (RV-6A  N1GV O-360-A1A, C/S, Flying 801hrs, Silicon Valley, CA)

lhelming(at)sigecom.net
Guest

Posted: Tue Jul 11, 2006 6:08 am Post subject: exhaust bolt torque

I torqued my O360 at 90 in-lbs.  They have not come off or loosened in over 

100 hours.  I checked them at last annual and they were all still tight. 

AND No leaks.



Maybe it should be considered to torque at the low end of Vetterman's or the 

high end of the published torque table in the manual.  I am sure Vetterman 

knows his stuff.  That is quite a spread between 100 and 140 however. 

Usually you find this type spread when a cotter pin needs to be used which 

is not the case here.  Indiana Larry



---

Hopperdhh(at)aol.com
Guest

Posted: Wed Jul 12, 2006 4:29 am Post subject: exhaust bolt torque

 

  

 Tom,

  

 I remember this coming up before, but not with the exhaust bolts.  The  torque tables for the airframe do not apply to the engine!  I personally  think that the low torque values used for the airframe have to do with clamping  aluminum and not crushing it.  The AN bolts are good for probably twice the  torque in the airframe tables.  (IMHO -- please don't hold me to that last  statement!)

  

 do not archive

  

 Dan Hopper

 RV-7A and longtime shade tree mechanic

  

  	  Quote: 	
		  >    --> RV-List message posted by: sarg314    <sarg314(at)comcast.net>

 	  Quote: 	
		  

 I was going to torque down the    nuts on the exhaust studs on my O-360 when 

 I noticed a contradiction    between my torque tables and Larry Vetterman's 

 instructions.     Larry says to torque the nuts to 100- 140 in-lb.  That's 

 the    torque value for a 5/16-24 bolt, according to my table.  But the 

    exhaust studs in my engine are 5/16-18.  The torque table says to use    

 80-90 in-lb for the coarse thread 5/16 bolts.

 What's the    right torque value here?



 --

 Tom Sargent,    RV-6A

az_gila

Joined: 17 Jun 2006
Posts: 99
Location: Tucson, AZ

Posted: Sat Jul 29, 2006 9:12 pm Post subject: Re: exhaust bolt torque

The torque values you are looking up are for airframe bolts.



The Lycoming Direct Drive Overhaul Manual has it's own set of default torque values.. and they are only for the coarse thread bolts (no fine thread bolts on the engine)



#10     49  in. lb.

1/4      96  in. lb.

5/16   204  in. lb.

3/8     360  in. lb.

7/16   600  in. lb.

1/2     900  in. lb.



They also call for lubricated threads except when otherwise specified.



Lycoming also has another set of instructions for crush type copper/asbestos gaskets - which I believe the exhaust gaskets would fall under.



In this case, for a 18 threads to the inch bolt/stud, tighten until surfaces are in contact and then tighten another 135 degrees.



This is only if the exhaust gaskets fall under the description of a "crush type" gasket 

Perhaps a A&P can help out here... I'm only an airframe mechanic...       ... but I got the Lycoming book...



gil in Tucson

rv9jim(at)juno.com
Guest

Posted: Sun Jul 30, 2006 8:27 am Post subject: exhaust bolt torque

Gil,

        I don't have the overhaul manual but I need the size of the bolts

that go into the machined boss that was origionally used for the

generator on the lycoming o-360.  This is an area that has three tapped

holes just on the generator side of the case.  It is bigger than a 1/4"

but not 5/16".   I want to support the starter cable as it leaves the

starter and heads back to the start solenoid.  With an adel clamp in that

position, it will releive strain where the start cable attaches to the

starter.

Jim Nelson

az_gila

Joined: 17 Jun 2006
Posts: 99
Location: Tucson, AZ

Posted: Sun Jul 30, 2006 8:47 am Post subject: Re: exhaust bolt torque

Jim... I don't have my parts manual here - a different book from the overhaul manual - but Lycoming only uses US coarse thread screws.



If it's not 1/4, then I bet it's a 5/16-18



Buy a cheap 5/16 bolt from the hw store and see if it threads in.   It should not be an odd size.



gil in Tucson

Hopperdhh(at)aol.com
Guest

Posted: Sun Jul 30, 2006 9:04 am Post subject: exhaust bolt torque

I'm pretty sure its a 1/4-20.  It is on my IO-360.

  

 do not archive

  

 Dan Hopper

 RV-7A



  

  In a message dated 7/30/2006 12:52:14 P.M. Eastern Daylight Time,  gilalex(at)earthlink.net writes:

  	  Quote: 	
		  -->    RV-List message posted by: "az_gila"    <gilalex(at)earthlink.net>



Jim... I don't have my parts manual here    - a different book from the overhaul manual - but Lycoming only uses US coarse    thread screws.



If it's not 1/4, then I bet it's a 5/16-18



Buy a    cheap 5/16 bolt from the hw store and see if it threads in.   It    should not be an odd size.



gil in  Tucson

bicyclop(at)pacbell.net
Guest

Posted: Sun Jul 30, 2006 10:36 am Post subject: exhaust bolt torque

Watch out for those crush type exhaust gaskets. I had one of those burn

through allowing the nuts to loosen and fall off. The pipe was found

hanging (barely) on the end of the stud. I replaced it with a solid

"blow proof" gasket. I checked the other 3 gaskets when we got home and

they all showed signs of damage and some leakage. Replaced all. 700

hours on engine at the time.



Ed Holyoke



 	  Quote: 	
		  Lycoming also has another set of instructions for crush type

copper/asbestos gaskets - which I believe the exhaust gaskets would fall
	


under.



 	  Quote: 	
		  In this case, for a 18 threads to the inch bolt/stud, tighten until

surfaces are in contact and then tighten another 135 degrees.
	




 	  Quote: 	
		  This is only if the exhaust gaskets fall under the description of a

"crush type" gasket 
	


Perhaps a A&P can help out here... I'm only an airframe mechanic...

[Wink]      ... but I got the Lycoming book...



 	  Quote: 	
		  gil in Tucson

FLYaDIVE(at)aol.com
Guest

Posted: Wed Aug 02, 2006 1:56 pm Post subject: exhaust bolt torque

In a message dated 7/30/06 2:38:01 PM Eastern Daylight Time, 

bicyclop(at)pacbell.net writes:



 	  Quote: 	
		   Watch out for those crush type exhaust gaskets. I had one of those burn

  through allowing the nuts to loosen and fall off. The pipe was found

  hanging (barely) on the end of the stud. I replaced it with a solid

  "blow proof" gasket. I checked the other 3 gaskets when we got home and

  they all showed signs of damage and some leakage. Replaced all. 700

  hours on engine at the time.

  

  Ed Holyoke

=======================
	


Ed:



You are 100% right on!



A cheep friend, purchased a set of those soft -- gaskets (guaranteed to  

blowout) and not one, but two of them were totally burnt out and missing.  The 

exhaust pipes were just barely hanging there. There was so much noise but he was 

more interested in flying than looking under the cowl.  In the process he also 

ruined two exhaust mounting studs.  So did he save any money?  I don't think 

so! ! ! 



Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada

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