header coming free

What ex gasket are you using? If it's the soft graphite ones, they squish and burn out way too easily on an ohv engine (ok on a flathead but not worth a plug nickel on a 206.) I use only the RLV copper ex gaskets - they will last AND keep the bolts tight.

Make sure that your bracing is neutral (not putting pressure on the pipe itself. Safety wire should be run from the head of one ex bolt to the head of the other (pulling clockwise so that they keep the bolt from loosening.)

Do NOT use loctite - there is no need for loctite on any engine bolt (in my opinion.) Your engine builder will thank you for not using loctite on bolt threads!

--
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cuts
www.CarlsonMotorsports.com
Celebrating 25 years of service to the karting industry
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Safety wire just makes sure you beat your threads to death by the time you know its loose as to make extra sure you need a heli coil job. If that little wire is in charge of keeping something tight we are all in trouble :)
 
I heat parts up with a torch to get lock tight to loosen up.
Doesn't the exhaust do the same thing to the lock tight on the header bolts?
 
Laugh if you want guys, but that little wire is used on every military bolt in a jet engine (especially bolts that are affected by high heat.) Titanium, Inconel, composites, it doesn't matter, it's all safety wired.

I agree that bolts should not be "held tight by the safety wire", but they sure can keep the bolts from turning.

Gary, if the bolts are safety wired correctly, the bolts can't turn enough to beat out the thread bosses -- you guys need to look at how you are safety wiring better. :)

Jimbo, Loctite has no business on any engine bolt (in my opinion) as stated above. Even red Loctite will be worthless on the exhaust side for the exact reason you gave. Loctite does do a good job of messing up the threads though when you pull it apart cold and is a pain to clean up. :)
 
I prefer to just tighten correctly the time with high temp silicone and checking periodically. To each their own though
 
The correct torque should hold it and a proper safety wire will prevent it from loosening. If torque and safety wire is right, then it sounds like you have another issue: damaged threads, warped surfaces, misalignment, improper gasket, excessive vibration or EGT, etc.
 
The majority of failures associated with header bolts, seem directly linked to improper bracing of header & muffler. Agreed above, if all is correct, failures are rare. Some guys will go right to steel threads, for the added security. I'd guess your bracing system might need some attention. Look around at the track, most racers got smarter w/ support, after suffering through the same problem you're experiencing. As for the right way to safety-wire the bolts, some people wire to appease the rule-makers, others, to insure the bolts don't back out!
 
gary10 said:
Safety wire just makes sure you beat your threads to death by the time you know its loose as to make extra sure you need a heli coil job. If that little wire is in charge of keeping something tight we are all in trouble :)
Click to expand...
A properly safety wired bolt cannot come loose, it is the best defense we have, locktite does not work in this application.
 
Kart43 said:
A properly safety wired bolt cannot come loose, it is the best defense we have, locktite does not work in this application.
Click to expand...

That's a bit optimistic. Safety wired fasteners can and do lose considerable preload (enough to cause problems in services like exhaust systems), they just don't come so loose they fall out and land in the bilges (or on the track, in this case) before someone notices. As you say, it's the best defense we have, but don't trust it to keep that joint leak tight over the long haul even when properly executed with regard to direction of fastener tightening rotation, just be happy you won't lose the bolts. Safety wire properly, but check fastener tightness often.
 
Outrider said:
That's a bit optimistic. Safety wired fasteners can and do lose considerable preload (enough to cause problems in services like exhaust systems), they just don't come so loose they fall out and land in the bilges (or on the track, in this case) before someone notices. As you say, it's the best defense we have, but don't trust it to keep that joint leak tight over the long haul even when properly executed with regard to direction of fastener tightening rotation, just be happy you won't lose the bolts. Safety wire properly, but check fastener tightness often.
Click to expand...

So the military only uses safety wire on Heli rotors so they don't lose the $249 bolts, sold to them by a congressmans company.
 
Brian
I misread your message. I just read it again.
I thought you were saying to use locktite on the ex bolts.
I apologize.

I will say that i don't like the safety wire rule. I hate doing it and see it as an obstacle to checking the bolt torque between races.
(Which you should do)
I also don't think the safety wire will keep a pipe from falling off during a race.
I think the exhaust bracing should do that.
If the rule organizations feel they need to wire the pipe on then wire the pipe on and not the bolts.
Wrap the (specified size) wire around the pipe and tie the other end to something substantial on the engine.
By the way, RLV now has a piece of metal on the muffler just to safety wire it to the pipe.
 
Kart43 said:
So the military only uses safety wire on Heli rotors so they don't lose the $249 bolts, sold to them by a congressmans company.
Click to expand...

No, the military uses safety wire as a set of suspenders to go with the belt of tightening procedures that yield high initial preloads and minimize (to the extent that it is possible to do so) fastener to fastener preload variation. High initial preload (comensurate with the joint design and fastener material choices) and minimization of fastener to fastener preload variation around a bolt circle always have been and always will be the cornerstone of mechanical joint integrity. Safety wire prevents total loss of the nut (or bolt when used on a bolt in a blind hole) - nothing more, but nothing less, and usually preventing total loss will get you home, or result in a situation which yields an obvious visual indication of impending failure (like a minor leak in a piping system joint) so that repairs can be initiated. The earliest attempts to prevent in-service loosening of a fastener most likely involved lock wires, keys and cotter pins, and these methods still find a lot of use, but these methods are not very effective at preventing large loss of preload. 2 degrees of rotation of the nut can reduce preload by over 1/4 of its total value, 6 degrees can reduce it by a bit over 40%, and both these rotations are possible (and have been recorded) in nuts and bolts that were properly safety wired. Lock wire systems aren't intended to provide tight control of nut (or bolt head) motion over the long haul, thay are, to re-emphasize, there to prevent total loss of the nut or bolt. Even if they save the nut or bolt, the loss of preload often leads to fatigue or other types of failure. It must be remembered that in bolted joints subject to cyclic loads, all that is necessary to cause low cycle fatigue failure is for the cyclic load to exceed the preload (NOT exceed the yield strength, but only exceed the preload) of the fastener, and this is a condition that often exists when fasteners lose preload in service. Are you familiar with the maintenance schedule for the fasteners on heli rotor heads? They get enough scheduled regular attention that safety wire will usually get you home even if a problem develops, or at least the maintenance schedules used on Navy and Marine Corps helicoptor rotor heads do; I can't speak for the Army or the Air Force helicoptors, but I seriously doubt that the planned maintenance schedule for them is much different.

As for $249 bolts, you can get there without even using a congressmans's company in some services if you have to order in small lots (like 6 or a dozen) to cover unanticipated repair needs. Hull integrity joints (joints that keep water out of the people tank) on a submarine are required to have a Material Identification and Control package that covers them from darn near when the ore comes out of the ground in the Mesabi range or wherever until the finished fastener is installed on the submarine, and each fastener is marked in a manner that makes it traceable back to the specific MIC Level I package that covers it's manufacture. That means a routine largish alloy steel nut that would cost $3.00 at a local industrial supply house costs a lot more to the Navy. But the price of that documentation package doesn't change much whether the supply system (or a Contractor) has to buy a dozen in a hurry or 3000 to cover anticipated needs over the next 18 months, so if you buy 3000, the per nut cost goes down to pennies apiece. Then, of course, there are the special applications that not only use MIC Level I fasteners but are made from various types of semi-unobtainium for which the bar stock is made by small producers in relatively small lots only on special order. Unfortunately, due to the materials required to meet space and weight constraints for use in certain critical services and traceability requirements like MIC Level I, $249 bolts or nuts are more common than you would imagine, even when not bought from a Congressman's company, though fortunately they aren't the norm, in either submarines or helicopters, though we probably have more on subs, just because we have a few more critical mechanical joints.
 
To never use loctite, or similar, is the worst advise I've seen on the forum for a long time.

The sole purpose of safety wire is to keep the wired bolt/nut, from falling off.
It is of no value in keeping tension/preload on the bolt assembly.

Oh, and Outrider......terrific post.....and not just for the issues you covered.
I hope (but do not expect) that some readers of this stuff, will have a little light bulb
come on, which suggests that the readers knowledge is very limited about the science
involved in most of such subjects as this, which are aired out on this forum.

It is headshakingly painful to read guys speaking as experts on subjects they know almost
nothing about.
No aspect of the work we do has escaped full analysis and vetting by
scientists.
That extends from bolt and nut material mating, to stress levels, to loc-tite.
 
One issue I have seen that has caused a problem with bolts loosing their tension is over-torquing the fastener. Something comes loos and many racers tray and solve the problem by tightening the bolt even more. WIth a 6mm bolt in aluminum threads, this is a mistake, IMO. When the head gets hot and expands, if the bolt is to tight it tears out the the threads on its own. Spec torque is 100 inch pounds which doesn't feel like much.
 
The worst advise I've seen lately is not to use over 12 ounces of oil.
I'd like to hear an explanation for that one.
Please share with us what the part number is that you use for the exhaust bolts.
 
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