cam cap bolts

[kneedown]

Hi guys

Won't bore you with long story, doing valve clearences and checked the cam cap bolts and three of them are cracked, I know it was done before and I am thinking way overtightened (not by me).

Anyway I will replace all of them and was wondring if there was any harm in using stainless steel bolts instead of the original ones. As long as they are the same size and pitch. Any thoughts or experience of this.

If tourqed correctly I cannot see what difference it would make.

Thanks guys

[misscrabstick]

Here's some proper bad news for you, cam caps are line bored with the cylinder head during manufacture, they are a matched set with the head, one does not replace them on their own.

Those from another engine will not quite line up with the other half of the cam bearing surface leading to the camshaft being pinched and binding with possible subsequent overheating and seizure.

[kneedown]

Hi I am fully aware of this and was asking about the bolts not the can caps, three of the bolts which secure the can caps were cracked not the caps themselves, as such I wanted to replace them with stainless bolts.

Thanks

[misscrabstick]

OOhhh ,ok sorry, how is the bolt cracked? shearing I understand, stripped thread I understand but cracked?

Only issue I could think of with stainless would be expansion related and possible slackening or something.

[kneedown]

Don't know the how just looked all of them over before reassemble and noticed the cracks. Was thinking.of the stretch also but can't see it being an issue with such short bolts (40 mm ) maybe for head bolts but don't know for cam cover bolts

[Kickstart]

Hi

1 cracking would be a surprise. 3 is very strange. Unless something fairly extreme has happened to the engine.

Other potential issue is spalling.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[kneedown]

Hi Keith

What's spelling? Would you say not to use stainless bolts then

Thanks

[Raffles]

Are you able to provide pictures to clarify exactly what you are talking about?
BTW you spelled 'spalling' incorrectly in your above post.
____________________
A good loser will always be a loser.

[kneedown]

The bolts are a very light metal and I belive they were overtightened by the last person who had a play with the engine and the stresses of doing them up/undoing etc has caused them to crack.

No real issue with the bike only opened to do clearances. Was going to use stainless because of availability and cost. Would you advise against it.

[kneedown]

All I really need to know is can the standard bolts be replaced with stainless bolts of the same size and pitch without causing any damage.

Thanks

[Kickstart]

[Major Doss]

Is there a number stamped into the bolt head? Use that as tensile reference, but it is also more likely mild steel rather than S/S.
Why not get OEM? Peace of mind for a tenner? If it were my camshaft I were looking after, etc...
Well done for you spannering and spotting btw.
____________________
Antisocial phucker.

[stinkwheel]

Stainless is going to be weaker, more expensive and more brittle than mild steel.

Corrosion is not going to be an issue inside the rocker cover.

As such, there is absolutely no good reason to use stainless for that application. Mild steel is stronger, cheaper and less likely to fracture.

There is also the question of how tight you need to do them up. The torque rating specified is for that exact grade of steel bolt. You risk either over or under-stretching the bolt if you use a different grade which could result in it either snapping or working loose.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Fizzer Thou]

I used some stainless Allen bolts on my Honda 750 cam caps once.As soon as the engine started two of the heads sheared off as the tensile strength was not the same as the original bolts.

Good thing that they did not go when being red lined

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Honda%20750/My750014.jpg
____________________
Just talk bikes.What else is there?

Always have a 'Plan B'

[bladerunner]

As said above...get oem replacements for peace of mind. No advantage of fitting ST/ST bolts in an oil filled environment and the std bolts will match the recommended torque figures.....just not worth the risk of it killing an engine.
____________________
Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[kneedown]

All good points and duly noted. Will bite the bullet and order OEM gonna replace them all to be safe.
Thanks for replys guys and gals

[YBR Ric]

kneedown, how tight do the bolts need to be on your engine?

I've just done my Triumph shims and the cap bolts only require 10Nm, just over 7Lb-Ft in old money.

[Vincent]

Using odd bolts could throw the torque settings off so you do well using the original ones.
Any chance you can post a pic of the damaged bolts? I'm a bit confused about "cracked" bolts too
____________________
Space Is Deep