Cam bearing cap bolts, prone to breakage?

[Bill S]

Hello, first time post here. I'm helping a friend set valves on a 1979 CBX. Since we had to swap all 24 shims we decided to remove the left side cams completely and loosen all right side bearing caps (and prop up the right cams) so all 24 shims could be swapped/replaced while leaving the crankshaft in one position. We assume the cam bearing caps had never been removed before, and when loosening the bolts most took LOTS of force to break loose and made a loud crack sound. The shim swapping went smoothly, but two of the cam cap bolts broke when reinstalling. They broke at just the "finger tight" stage of tightening. So we decided all the bolts are suspect and have ordered NOS replacements.

So my questions are:

-Are these bolts prone to breaking?

-From the loud "crack" sound they made when loosening it seems the threads were partially seized in the head, so is there a recommended way to break them loose before removing, like smacking with a brass drift and hammer?

-Is this a known problem, and are aftermarket bolts available? (We already have NOS originals on the way, but are just curious what options are out there.)

We will be using anti-seize compound on the new bolts when reassembling.

Thanks in advance for any advice.

-Bill

[Jeff Bennetts]

Hello Bill, yes it's a known problem and a member of the CB1100F forum sells replacement bolt kits, can't recall his forum name but he is a small parts vendor who sells CBX and CB1100F stuff, someone will come along here and help me out with his contact info.

40 yrs of steel bolts in a aluminum head will do that, it wouldn't hurt to chase each the bolt holes with a flat tipped tap and blow all the white dust and corrosion out, I'd skip the never seize and just apply some light oil to the bolts, a little dab will do you.

Good luck and have fun with the CBX!

[steve murdoch icoa #5322]

Contact Gene at genesound@usa.net for info on the bolts.
I think he still selling the viton valve seals as well.

[Larry Zimmer]

Be careful with the torque of these bolts. The cylinder heads are known to have some porosity in them. If it is in the area of the cam bolt threads, stripping is a possibility. Time Serts are not cheap. BUT, they do work. If you oil the bolts, I would suggest staying at the mid-torque spec; or even just a nudge below mid-point. Just one guy's experience.

[Bill S]

Thanks to all for your replies. Since we did manage to find NOS original bolts we will use them. I agree on aiming for a mid point on the torque spec especially when threading into an aluminum head. My practice is to always apply anti-seize compound to all threads, then torque to the midpoint or less depending upon feel.

-Bill

[daves79x]

Anti-seize is not recommended here,or any other internal engine bolts. Just do as Honda says and lightly oil the threads.

Dave

[hondaman160mph]

Anti-seize is not recommended here,or any other internal engine bolts. Just do as Honda says and lightly oil the threads.

Dave

Why is that Dave? I thought anytime a steel bolt went into aluminum a little anti-seize was a good idea

[twowings]

Most anti-seize compounds have metallic particles and other solids used as fillers. I wouldn't want to use them internally as these components can be washed into the oil and that would ruin your engine shortly. My employer had an assembler that decided to use Never Seize on hydraulic pump shaft splines rather than Moly paste and it was incredible how rapidly they failed. I checked the ingredient list and one of the fillers in thsi particular product was ground calcium carbonate (limestone).

[Jeff Bennetts]

Most anti-seize compounds have metallic particles and other solids used as fillers. I wouldn't want to use them internally as these components can be washed into the oil and that would ruin your engine shortly. My employer had an assembler that decided to use Never Seize on hydraulic pump shaft splines rather than Moly paste and it was incredible how rapidly they failed. I checked the ingredient list and one of the fillers in thsi particular product was ground calcium carbonate (limestone).

And as far as this application goes, Honda developed the torque tables used on your CBX with light oil being applied to the bolts, not anti, never or any other seize!

[daves79x]

What they said.

Dave

[Bill S]

Everyone, thanks for the comments. Point taken about anti-seize, I'll use only oil. The NOS cam cap bolts are on order but we could not find a full set so will have to reuse quite a few of the originals. But I'll stress test them by torquing to spec in a fixture before installing back in the head. I'll post back when it's all done.

-Bill

[Rick Pope]

Why stress test? Nowadays, many fasteners, especially in engines, are single use. So you only get one shot. Why waste it testing?

Tightening a fastener, stretches it. Depending on the material and loading, it may relax back to original, or not. Install them and forget it.

[Larry Zimmer]

Not to belabor this one; but, thought I would mention that the torque spec for these bolts is for a 10.9 class bolt, which they are. The significance is that this is a max range for this size bolt! And, that is for lightly oiled. Particularly, if you are not using a low range torque wrench, or doing the 'just tighten' thing, be a bit careful.

[Bill S]

Why stress test? Nowadays, many fasteners, especially in engines, are single use. So you only get one shot. Why waste it testing?

Tightening a fastener, stretches it. Depending on the material and loading, it may relax back to original, or not. Install them and forget it.

Could not find complete set of new bolts so need to reuse some old ones. Two originals broke when reinstalling before they were even finger tight. Luckily the broken ends came out without drilling. No way am I going to risk breaking off any more in the head. Hence the simple torque test, only on the used bolts, to the low end of the range.

-Bill

[herdygerdy]

May be a dumb question (but I am asking it with the greatest respect), but if you - and many others - have had failures with OEM bolts and yet there is a much better, tried and true solution out there (ie; genesound's bolts that are widely used with great success and no known issues) then why on Earth would you stay with the OEM bolts? Seems like you are setting yourself up for a very expensive fail down the track...
My two South Pacific pesos worth.