Topic: Tighten Cylinder Head Screws First Then Torque Head Nuts?

[Wingnut74]

I have read old threads that conflict on this so I am not clear, do you tighten the smaller cylinder head screws first because they are really just for alignment and intial seating? This is what I thought initially, but then I saw a post by Hondaman saying that these help prevent leaks - seems like if that were their primary purpose then they would go on second so that their inferior compression force was tacked on at the end and not first only to be overwhelmed by the studs at a way higher compression force? any guidance appreciated

[Jerry Rxman Griffin aka MuthaF'er]

My take: If you tighten them FIRST at ~8lb then you have to re-torque after you tighten down the main nuts to ~18lb. Dowels are meant for alignment. Perhaps just to initially seat and hold the head in place to torque the 16 nuts.   

[hotdog]

I was taught that any smaller bolts get always get torqued after the main cylinder studs/bolts. So as not to load up the threads in the alloy and risk them pulling out.

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[evanphi]

Small ones in hand tight to align everything, then torque the big nuts in sequence, then torque the small ones.

FWIW, my bike didn't have them installed when I tore my top end down last winter... I put them in.

[MCRider]

I was taught that any smaller bolts get always get torqued after the main cylinder studs/bolts. So as not to load up the threads in the alloy and risk them pulling out.

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That's my opinion also. Tighten snug. While I think the 4 6mm bolts are superfluous after the 16 nuts are tight, I would defer to HondaMan to go ahead and leave them in, tight to 8 ftlbs, to prevent leaks. Can't hurt.

Upon a disassembly (hope you don't have to) , I suggest removing them first. If you remove the 16 head nuts first, the head will relax into the 6mm bolts making them so tight you'll never get them out, as many have come to realize.

[MoMo]

rule of thumb is tighten from the inside out in a criss- cross pattern, loosen from the outside in with the criss-cross pattern

[Wingnut74]

OK Many Thanks! Going to to screws first, torque head nuts, then torque screws. Head is going on tonight - I know my NOS head gasket is supposed to be big enough for 1mm overbore, but holes are irregular and looks close! Think I might be saved by the fact that the piston crown looks to be about .030"? smaller diameter than the bore. Pretty sure its down to .0008" lower down on piston.

[grcamna2]

Torque them down in that 'X' pattern style evenly and it should keep your head gasket from deforming.

[Jerry Rxman Griffin aka MuthaF'er]

Is your head gasket for a F2/F3 with the oval chambers?

[Wingnut74]

Nope. It was for my K4 from Western Hills Honda, also where I got 3 of my NOS +1mm pistons, cha-CHING!

[70CB750]

Torque chart:

[calj737]

It is also recommended to let the motor sit 24 hours after torquing, then release the bolts, and re-torque to insure proper stretch of the studs and compression of the gasket. Much easier to do with the motor out. And follow the advice of MoMo about releasing the nuts. Torque in stages of 1/2 torque value, then 3/4, then full value always following the full sequence. Guaranteed results.

[Wingnut74]

Done as recommended. Feared the dreaded plink of a broken stud but all went well. Stud holes REALLY needed a good thread chasing session with some Alumatap, which is good stuff for tapping aluminum. Very glad I did that so you know your torque is not just fighting bad threads. thanks!

[Wingnut74]

I forgot to mention for the benefit of anyone who is on the fence about the need for re-torquing head nuts, (though I was not a doubter after reading enough posts), that when I went to back off the nuts, some were already not as tight as the day before very noticeably, and more interestingly when I re-tightened to the same torque, it took me to about 10 degrees further than the day before, so I think it actually did something.

[grcamna2]

It is also recommended to let the motor sit 24 hours after torquing, then release the bolts, and re-torque to insure proper stretch of the studs and compression of the gasket. Much easier to do with the motor out. And follow the advice of MoMo about releasing the nuts. Torque in stages of 1/2 torque value, then 3/4, then full value always following the full sequence. Guaranteed results.

That's very good advice

[ChopSticks]

Torque chart:

Are those torque settings with consideration of anti-seize? or should you set it 30% lower to 10.15 - 12.67 ft-lbs?

[70CB750]

The manual does not say, I expect to be dry values.

The only manual ever I found lubed torque values was a Novak transmission rebuild guide.

[MRieck]

 I recommend motor oil on the stud threads

[grcamna2]

I recommend motor oil on the stud threads

With motor oil on the cap nuts would you recommend using the factory torque specs ?

[MRieck]

I recommend motor oil on the stud threads

With motor oil on the cap nuts would you recommend using the factory torque specs ?

Yes. Are you worried about driving the oil up the nut and causing hydraulic lock? You don't have to drench....just lube it a bit.
That pic is an F2 head and that is the only one that using the copper sealing washers and acorn nuts. Those studs can handle more torque too. I put oil on the top of the washer too.

[scottly]

I usually repeat the final torque sequence several times; as the gasket compresses evenly, the nuts turn a little more each time. I never tried waiting 24 hours..

[Retro Rocket]

You guys just love torquing about your nuts.....

[ChopSticks]

I usually repeat the final torque sequence several times; as the gasket compresses evenly, the nuts turn a little more each time. I never tried waiting 24 hours..

Do you repeat torque with the same torque? or more? for example wouldn't torquing a bolt at 10lbsft then retorquing it with the same 10lbsft actually be torquing it more than 10lbft?

[mystic_1]

No, you torque them to 10 ft-lb, then over time they relax a little and they're not longer at 10 ft-lb, so you torque them BACK to 10 ft-lb.

mystic_!

[calj737]

Chopsticks - Part of torquing the bolt/nut against the stud is to allow the stud to stretch. If it stretches any, the nut is no longer torqued to its original value. Once the stud is stretched, if you release the nut, then return it to its original value, its compressing the head/gasket at the designed strength; theres no need it increase the torque simply because the stud is stretched.

Some folks torque, cycle the motor with a few running cycles, then re-torque. This is easier to do on a 5xx motor than a 750, hence encouraging the OP to wait 24 hours then cycle the torque/release/re-torque program. Now, they're good and his studs are stretched and his gasket compressed. Time to install and fire it up!