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72 CB350
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Discussion Starter · #1 ·
Finally have the valve installed and finishing the engine.I researched and I am unable to find the torque for the 8 CB350K4 SUPER SPORT 1972 USA BOLT, CYLINDER STUD.

Does anyone know the torque spec?

THX
 

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Best to check the factory manual, but I think the cylinder studs should be a bit under 20Nm, tighten in a circular pattern from the middle (best as in manual) and best do it in steps (tighten to 10Nm, then 15Nm, then ~18Nm final torque). A few days and heat cycles, then I'd untighten and retighten (18Nm is not a lot of torque, the gasket compresses and the nuts sit into the head with a few cycles... best retighten to make it hold consistently). Very important to thoroughly clean the threads and then lubricate the threads and the nut with engine oil very well! Without oil, the clamping force will be ~30-40% lower!
 

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72 CB350
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Discussion Starter · #6 ·
I am setting the timing and have the LT mark aligned, the line on the sprocket parallel to the cam case and the post at the 12 o'clock position. I suspended the cam with wire to keep the chain taut and after I install the two bolts in the cam gear the line on the sprocket is a little off parallel, see attached picture. When I rotated the engine in was in a CCW direction.

Is this within spec or does it have to be perfectly parallel?

I did this 3 times and ended up in the same position.

THX
 

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Not good enough. Needs to be parallel
One tooth on the crank moves it twice as far as one tooth on the cam gear. It is fussy.
Torque the cam gear nuts, I use red loctite as well, then work the parts into position.
Once you have it parallel then move the crank so that the pin on the cam shaft is at the 5 0'clock position. Have all the adjusters backed off. This position allows the cam supports to be slipped into place. Do not force them.
I put lube onto the adjuster shafts and the bottom of the cam supports to aid in assembly.
 

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72 CB350
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Discussion Starter · #9 ·
I PLACED THE ENGINE/CHAIN PERPENDICULAR AND THAT KEPT THE CHAIN TENSION EVEN ON BOTH SIDES SINCE THE CAM BEING SUSPENDED ON BOTH ENDS AND PROBLEM SOLVED!
ANYONE ELSE EVER DO THIS?
 

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Honda SL350K1
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Best to check the factory manual, but I think the cylinder studs should be a bit under 20Nm, tighten in a circular pattern from the middle (best as in manual) and best do it in steps (tighten to 10Nm, then 15Nm, then ~18Nm final torque). A few days and heat cycles, then I'd untighten and retighten (18Nm is not a lot of torque, the gasket compresses and the nuts sit into the head with a few cycles... best retighten to make it hold consistently). Very important to thoroughly clean the threads and then lubricate the threads and the nut with engine oil very well! Without oil, the clamping force will be ~30-40% lower!
Hi to all,
Very interested in the last sentence here (about lubricating the head studs) - I thought that Honda required (unless specifically specified) that when torquing nuts / bolts that the threads be dry. I agree that lubricated threads will apply significantly greater clamping force when torqued to the same spec as dry threads.
Can I ask (pikl) where the lubricated threads process is specified please.
Cheers
Mike
 

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I thought that Honda required (unless specifically specified) that when torquing nuts / bolts that the threads be dry
CB350 manual only specifies the torque. However, they forgot to note it. CB350 head stud uses an M8x1.25 fastener. At 180kg cm, that's around 17Nm. The standard max torque for M8x1.25 for 8.8 grade screws is 25Nm (this value is on the "safe" side and rounded downwards and it gives repeatable results) for dry threads - 255kg cm. Force increase with using 15w30 engine oil is around 30-40% (graphite would be even a bit more). 30% off of 25Nm is 17.5Nm or right around 180kg cm!

Of course, 8.8 grade are generic screws used on motorcycles, the cylinder studs are undoubtedly 10.9 or even 12.9 grade, that means the specified head torque on the CB350 with oiled threads is very far on the safe side.

The CB360 does specify oiled threads under notes. It has nearly twice the tightening torque on M10 fasteners - around 30Nm. The safe max torque standard for M10 is 50Nm. So that's exactly a 40% reduction off of that. BTW the M6 bolt is really tightened to the limit though - the factory one which is probably high tension (10.9 or 12.9).

Font Brand Auto part Monochrome photography Rectangle


CB450 also does not specify lubricated threads, but has the identical torque specification as the CB360 - 3 kg m.

Dry torque value is a vague recommendation, it is never exact. Cylinder head studs are always lubricated, I assume Honda forgot to include it in the manual because the torque values seem to be appropriate for lubed threads.

 

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72 CB350
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Discussion Starter · #12 ·
Major F'up.🤬 I did not mark where the rocker arms were originally. I labeled everything else. Any suggestions? It looks like one is bigger than the others.

As always thanks for any help.
 

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