should I retorque head bolts when I do my shims?

[jono]

I rebuilding a 1991 3xw 1200 Ive ordered my shims from rpm and am waiting on them to arrive .  When i bought the bike it was ride able  but the whole bike was not roadworthy so  I haven't had the pleasure of grabbing a handful of throttle yet  ,ive remounted the carbs with new o rings and refitted the airbox correctly but the shim clearances were out of spec so after riding it up and down the drive way a couple of times on the first day  ive not ridden it  and wont until my shims are set up .What I need to know is can I safely re torque the head bolts before I do my shims or do I even have to? its done close to 90000 k's it doesn't leak or show any signs having leaked .I know being a ohc  motor torgueing  the heads will have no bearing on the shim clearance  but should I check them and is it safe to do so with the motor cold ,and is there a correct way of doing this ?

Jono

[CutterBill]

Sure, it won't hurt anything. You're just checking to make sure that none of them have come loose. Engine cold...

Do NOT get some crazy idea that you need to loosen all the nuts first, then retighten. Don't do that. Just check the torque.
Bill

[RPM - Robert]

No.

The FJ is common for rusting the head nuts on the studs and thus you will not get a proper torque.

Fred experienced this exact thing on his recent head replacement. Look at this post and you can see two studs missing from the engine. That's because they unscrewed from the block instead of having the nut come off. two new studs and nuts later and he was ready to go back together. http://www.fjowners.com/index.php?topic=19170.msg194707#msg194707

Plus, you really do not want to disturb the fiber base gasket and create leak.

[Ted Schefelbein]

No.

The FJ is common for rusting the head nuts on the studs and thus you will not get a proper torque.

Fred experienced this exact thing on his recent head replacement. Look at this post and you can see two studs missing from the engine. That's because they unscrewed from the block instead of having the nut come off. two new studs and nuts later and he was ready to go back together. http://www.fjowners.com/index.php?topic=19170.msg194707#msg194707

Plus, you really do not want to disturb the fiber base gasket and create leak.

That is why we are here. Thanks!

Ted

[CutterBill]

The FJ is common for rusting the head nuts on the studs and thus you will not get a proper torque...

So what's the downside of checking the torque?

If the nut is rusted to the stud, there will be no rotation of the nut. Net effect: no harm done.
If the nut is by some chance loose, it will be tightened to the proper torque. Net effect: potential problem averted.

No one said anything about disturbing the base gasket. That's why I specifically mentioned to NOT loosen the nuts. So what's the downside to just checking for loose nuts?

If you are a conscientious rider, you routinely check lots of important bolts and nuts for tightness. You check spark plugs, axle bolts, brake rotor bolts, frame bolts, exhaust pipe nuts, shifter bolts... on and on. But somehow head nuts are some magical, mystical nut that should only be torqued once in the life of the engine and then never checked again? Nonsense. I would much rather find a loose head nut, or any other bolt/nut, in the shop, rather than 1000 miles from home.
Bill

[jono]

Thanks guys
I can see that if i tighten the nuts and they are frozen to the studs the movement of the stud could disturb the base gasket .And it doesn't leak at the moment so I will carefully check the nuts for looseness and be careful not to disturb anything,  hopefully every thing is tight .
this forum is so helpful I saw it online before i bought my bike and the fact it existed and the fact engine parts are still available thru outlets like RPM helped me decide to buy the bike
jono

[racerrad8]

The FJ is common for rusting the head nuts on the studs and thus you will not get a proper torque...

So what's the downside of checking the torque?

If the nut is rusted to the stud, there will be no rotation of the nut. Net effect: no harm done.
If the nut is by some chance loose, it will be tightened to the proper torque. Net effect: potential problem averted.

No one said anything about disturbing the base gasket. That's why I specifically mentioned to NOT loosen the nuts. So what's the downside to just checking for loose nuts?

If you are a conscientious rider, you routinely check lots of important bolts and nuts for tightness. You check spark plugs, axle bolts, brake rotor bolts, frame bolts, exhaust pipe nuts, shifter bolts... on and on. But somehow head nuts are some magical, mystical nut that should only be torqued once in the life of the engine and then never checked again? Nonsense. I would much rather find a loose head nut, or any other bolt/nut, in the shop, rather than 1000 miles from home.
Bill

Bill, don't get all wound up.

A couple of questions for you?
  1) How do you recommend "checking" the torque?
  2) When was they last time you checked the head nut/bolt tightness on your (insert your street car here)?


Robert passed along what he has been taught when working on FJ because I do not recommend re-torquing head nuts. That answer was based on Jono's question.

A couple of things I have observed with the FJ lump that can result in problems since you asked.

First, The studs are bottomed in the case and if the head nut is stuck on the stud, they you are just loading the case threads to excess and risk pulling the threads.

Secondly, since the stud is designed to be and is "stretched" and under tension when torqued, then you cannot truly "re-torque" the head nuts without loosening the nut. Because if you don't, in order to get them to "tighten" more you get that "snap" and that is much more torque than 25 ft lbs. (pulled threads or pinched base gasket)

Finally, if the user's torque is not calibrated properly and it is set to 25 ft lbs, but actually is 30 ft lbs, then it will over tighten the nut and pinch the base gasket out and create a leak. Or the opposite, too loose and lets the head & cylinder float and cause a leak.

But, if he just wants to put a socket on them to see if they are loose, then have at it. But if he finds one loose, there is usually a problem associated with that loose nut. (Pulled case threads, broken stud, bad base gasket)
If it is loose, then the nut needs to be removed, the threads cleaned and lubed, including the washer surface, and then properly torqued.

The only time I recommend a re-torquing of the head studs is on a complete rebuild during the break-in process. After that initial re-torque I do not recommend touching the head nuts again.

I guess I must not be a conscientious rider because I have never checked the head torque on any FJ motorcycle I have ever owned or a Chevrolet, Dodge or VW.

Randy - RPM

[jono]

the main reason I inquired about re torqueing the head was this vid on u tube " https://www.youtube.com/watch?v=zCa556ObEi8"  maybe I should of used the term " check the torque" instead of "re torque" the head  I now have very good idea on what to do and what not to

thanks

[Ted Schefelbein]

I was looking at those bolts after I got the valve cover off, thinking I should check them, but, they look like they have been in the same place a long time. Steel bolts in aluminum parts will lead to galvanic corrosion, and after this many years, I am going to lean in to leaving them as they are. I'll deal with snapped bolts and pulled threads when it is time for a rebuild.
Hopefully, a good ways off from today.

Ted

[racerrad8]

Jono,

That is in reference to the FJ engine used in the race car application. Back in the beginning when I started with this race car in 1994, if you did not stay in the top of the head nuts, you could have a head gasket chirping after just one night of racing. It became common practice to "re-torque" the head on the race car for several reason that are different from the motorcycle. But we would usually have to pull the head half way through the season to replace the gasket and fix at least one stripped case stud.

1) Heat.
    In the car, the engine is mounted sideways and the engine is being poorly air cooled and overheats. The heads get hot enough to displace the aluminum under the tension of the head nuts. The stay sealed when hot, but they are loose when the head cools down. So, people like to keep re-torquing them and that continues the cycle of aluminum displacement and eventual head gasket failure, broken studs or pulled case threads.
2) Structural member.
    In the race car, the engine is the structure member of the front frame section of the car. The engine is twisted and pulled in axis' that do not exist on the FJ frame. The rear lower motor mount lugs break off just from normal driving around the track. The cylinder heads crack and the exhaust side at the cam chain kick-out between #2 & #3 cylinders (excessive heat and flex)

There have been many attempts to mitigate the issues this engine sees in the race car application. From stronger studs, case thread insert slugs, bigger & different profile head washers under the nuts, to guys welding slugs between the fins of the head to eliminate the aluminum displacement. While something might work, it usually reveals the next weakest link and the search continues, for more than 25 years now. Engine builders all over the country and the world for that matter have a unique take on how to resolve this issue. Some are somewhat successful and others, like myself have developed procedures that are very successful.

The one thing we do not do, even on our race car engines is "re-torque" of head nuts. With the use of better cooling techniques, materials and procedures we have been very successful in keeping the head properly torqued and the need of re-torquing them has all but been eliminated.

One the note of "re-torquing". The best procedure is to check the torque value (tightness) when loosening the nuts. You must have a torque wrench that can read for loosening or left-hand threads to do this. You can then verify if the nuts are properly torqued when they are being loosened.

Again, I do not recommend this on the FJ because of the common issue of the rusted nut onto the stud as you will be turning the stud in the case. No matter what happens in that scenario, you are going to have more work to do for something that was most likely properly torqued to begin with.

Randy - RPM

   

[jono]

thanks Randy

the head nuts seem quite badly corroded just looking at them so I'm gonna go the same way as Ted and leave well alone

I'm glad I asked I think I might have saved my self a whole lot of unnecessary work 

thanks again guys
jono

[ribbert]

I agree with Randy, leave them alone.

I can tell you as sure as the sun coming up in the morning, performing unnecessary tasks on a vehicle is asking for trouble.

In this case you would only be doing them one at a time but you would still be advised to understand how to use the wrench and static vs dynamic friction.

There is also a risk of damage to other components from unnecessary handling such as fuel tank, paint, fairings, hose fittings, threads etc.
One of our members very carefully placed his mint black FJ fuel tank up side down on rags with the greatest of care while he accessed the top of the motor. Seeping fuel totally ruined the paint. Another one snapped off the petcock sliding it onto the bench, put a part on the floor then drop kick it into the next suburb and so on. Don't kid yourself you wouldn't do anything stupid, we've all done stupid.

Noel

[jono]

I appreciate the advice noel just to let you guys know what I' m up to. The first picks are when i bought the bike that's all there was' there were no other spares no old parts just the bike in the pictures the guy I got it from  dropped it then put it back together like this, then sold it to me so i am going over the whole bike and rebuilding what ever needs putting right  I started with measuring the shims and ordering them from RPM. I'm waiting on them now but plenty to do in the mean time I've fixed the front head light frame wiring loom and have got the control looms tidied up and rerouted correctly.  
Ive re mounted the carbs with new o rings ,Ive stripped and cleaned the front brake calipers and am waiting on the rebuild kits to arrive from the states I've got new pads and good used rotors coming from Canada my next job is to sort out the wiring loom on the main frame as you can see its a mess this bike was an ABS model but the previous owner removed the ABS , he did it properly as the bike starts and every thing works ,lights,indicators  eceiterer  but the wiring is crap crimps and cut wires every were that's my next job at hand ,Ive got new air scoops for the fairing  and rear side covers coming as well .I've fitted new stainless megaphone mufflers that are  ready to weld an then they bolt straight on ,once i do my shims and get the pipes fitted Im going to start it up see how it goes which I'm thinking will be pretty good then I'm going the partially strip her down again and fix up the paneling choose a paint color scheme fix the front fairing up  at this stage I'm probably going to give the motor and frame a good clean and keep them black this is definitely not a full rebuild so I'm not taking the motor out of the frame  or anything like that ,i bought it to ride and that's what I'm gonna do

Jono

[aviationfred]

As Robert mentioned, when I removed the head for replacement 2 of the head acorn nuts had seized onto the cylinder studs. This may not seem to be that big of a deal, unless it is you trying to get it off. It was a very anxious and dreadful experience. The studs just didnt screw right out of the block. It took a tremendous amount of torque and the studs would move with a very loud SNAP, then repeat again. Every time it would snap I was sure the stud had sheared. Thank goodness my friend Roger was there with me, telling me to have patience and go slow.

I already have 600 miles on the new head. At 1000 miles I will be doing a valve adjustment check and torque check of the head nuts. Once done, the head nuts will be left alone.


Fred

[jono]

I'm glad I asked when I saw the clip on u tube I actually ordered a new torque wrench online but the more I thought about it the more I thought about it not being a good idea .My
initial worry was should I torque the head cold or wait till I can start the motor and torque it when its warm but what you guys have taught me is something I would never have thought of.
The  thought of studs snapped of in blocks is scary especially now for me now, when I was younger and buld uo a couple of motors I had access to a couple of very good workshops ,this time round its just me an my garage

Jono