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Cracked cam box

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I have just stripped my 1936 inter engine and found a small crack in the cambox. It goes through the narrow bit at the bottom of the bevel cover and the top bevel housing. The crack goes right through but nothing has moved and the rest of the cambox seems to be in reasonably good condition.

I have read quite a lot about the camboxs being a weak point on these engines, and I'm worried that getting it welded could cause more problems when the rest of the box heats up and cools down. I know a welder that can warm the hole thing up in an oven, weld it and then cool it down very slowly to minimise the risk but I'm still concerned.

As nothing else has moved, is just leaving it a better option? I have the bevel housing bolted up to one side and the cover bolted up to the other with screws at either end of the cracked section, so it should be well supported.

Has anyone experienced anything like this before? And if so what would you suggest?

Thanks

Andy

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Hi Andy

Suggest you log on to George Cohen's Web site on www.norton.co.uk and go into 'Expert advice & hints and tips', scroll down to Tip 21 - Inter' Cambox repairs, where all will be revealed.

Best of luck!

regards

Derek Ambler

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Sounds different to the problem George Cohen describes. Maybe a photo would help? If it is at the bottom, is it because it is heavily restrained (you describe it as 'well supported')? If so, the action of 'supporting' it by tighteneing everything up might have broken it - and it will therefore probably break again. If it is not a bearing housing, 'leave well alone' might be the best option. Just inspect regularly to make sure you catch it if the crack tries to grow longer and enter a critical area. There are lots of big structures out in the big world that have lots of cracks that engineers are monitoring because the cure might be worse than the disease - or the cost simply is not worth it because it is bound to crack again.

I imagine the oil leak from the crack (if there is one) is lost in the general oilyness of the typical Inter...?

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I wouldn't have thought that it would be too difficult a job to weld this, if it is where I think it is, especially if it is done in the manner mentioned - heating the whole housing up first. It doesn't strike me as being too highly stressed just there. Ian Bennett might be able to give you some advice, George Cohen too as well as Stu Rogers.

Ian Bennetts website:

http://www.doddington-kent.org.uk/Web_directory/Bennett_cnc/norton_parts.html

Regards.

Ian.

 


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