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Author Topic: Lister camshaft  (Read 2704 times)

ajaffa1

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Lister camshaft
« on: January 02, 2018, 12:19:08 AM »
Hi Guys, I have read a great deal about camshaft inaccuracy on imported Indian clone engines.
 I have sent a lot of camshafts for regrind over the years and these guys know what they are doing. Armed with the correct geometry and some oversized lobes a camshaft could be assembled and sent to the machine shop for accurate grinding. The camshaft could then be dissembled and the lobes hardened and tempered or case hardened before reassembly.
Any thoughts? Could Gary or someone source oversized lobes?
Bob

dieselgman

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Re: Lister camshaft
« Reply #1 on: January 02, 2018, 12:44:12 AM »
We can get standard lobes that can then be adjusted to a higher accuracy with a little careful measurement. Hardening of the lobes is a good idea as long as the tappets are also dealt with in similar manner.

dieselgman
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38ac

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Re: Lister camshaft
« Reply #2 on: January 02, 2018, 11:51:27 AM »
Worn or otherwise off spec camshafts are corrected in two ways. Which is used depends on how far off spec  the profile is.  For smaller corrections they reduce the base circle which allows the entire lobe to be ground yet retain the correct profile. Larger corrections  require welding if the the lobe material allows for that. Your cam grinder should know these things.  On a CS cam you have another choice as  machinist worthy of the name could bang out Lister CS lobe blanks, it's pretty basic machining.  My experience is the Indian cam lobes themselves are fine but they bend the shafts when installing them, or the positioning holes are off or in one case they had the intake and exhaust lobes switched on the shaft .   The bulk of the time straightening the bent shaft puts things in order timing wise.
John Ferguson put a lot of effort and $ into a custom cam project that was close to ready to go into production  but that project died when he left for central America. Not sure what happened to what was left  of that work but would save a lot of money for anyone willing to pick or up and run with it.
 
« Last Edit: January 02, 2018, 02:20:23 PM by 38ac »
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ajaffa1

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Re: Lister camshaft
« Reply #3 on: January 03, 2018, 11:05:40 AM »
Thanks guys, stripped the camshaft today. Shaft is bent and badly worn. 25 thou wear at the injector pump end, 6 thou at the other end. Add to this probably half as much again in wear in the bushes. Inlet and exhaust cam lobes look ok, a quick measure with a vernier calliper gives 314 thou lift on the inlet and 412 thou on the exhaust. The injector pump/oil pump lobe is history(poor lubrication and water ingress).

New bushes are readily available, a replacement shaft is not. I could go down the route followed by Dieselspanner and turn down the ends of the shaft and then make custom bushes or I could make a new shaft. I am tempted to make a new shaft, 7/8" ground silver steel is available from the UK and the holes are all in line so there would be no need for indexing.
I have no idea as to what the original shaft was made of, probably some sort of Sheffield steel, would silver steel hardened and tempered be a good replacement or would it be too brittle and break.

38ac

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Re: Lister camshaft
« Reply #4 on: January 03, 2018, 01:39:14 PM »
The original shafts were not made of anything special. The shaft material was what we call 1018 in the states.  In my world it is easier to build up a new cam instead of trying to fix very many issues. Although I use the milling machine all you really need is  a decent quality drill press and vise, the ability to get the holes in the correct position and in a straight line. and the correct tapered reamer and pins ( I think #6 but I would have to look) When building one I go with something a bit better such as 1144 StressProof but it is not necessary
If you have the desire I can help you with ideas for getting the holes in line using only a drill press and vise. The reamer and pins should be available in the UK, here I use McMaster Carr.
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ajaffa1

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Re: Lister camshaft
« Reply #5 on: January 04, 2018, 10:47:26 AM »
Thanks 38ac, I have a drill press and other assorted tools. What I don`t have is a vernier height gauge. If you know how to mark this out accurately without one I am all ears. I could perhaps use the original shaft as a template and drill though it into the new shaft.
I don`t live in the UK, I am a Brit living in Australia but I buy most of my engineering supplies from either the UK or USA. The reason for this is that if I place an order with an Australian business it takes months to arrive as they keep no stock and have to order it from Europe or the USA. It is always quicker and often cheaper to order it directly from the source. Postal charges are often the killer. I don`t understand how stuff from Hong Kong or China is usually cheaper and has free postage.
I will contact my local steel stock supplier with regards to ordering the new shaft steel, as always I will have to wait for delivery and pay too much, I will contact you when it arrives.

Thanks Dieselgman, I am building a spread sheet of all the parts I will be needing and you are no1 on my mailing list, primarily because of my previous good service experience.
Bob