Lister CS (genuine not Indian) cylinder head machining limit

[Anubis]

(I make the distinction between Genuine and Indian because there might be a difference)

I am needing to refurb by old CS cylinder head. Unfortunately at some time in the past, I suspect there has been a persistant head gasket leak which has allowed water into the combustion chamber resulting in erosion/pitting of the head, particularly around the mouth of the combustion port extending up to the edge of the cylinder gasket ring (IYSWIM). Skimming 40 thou would improve it a lot, 80 thou might just clean it up altogether BUT what is likely to be the safe machining limit?

If anybody has any practical experience to share I would be most gratefull.

[dieselgman]

20 thou maybe no problem at all... but 40 to 80? That is a bit drastic as far as changing the valve geometry. The head probably will have enough thickness in most cases but you will have to adjust everything for proper piston "bump height" (clearance to the head) and also valve clearance. At 40 to 80 thou you would most likely have to sink the valves in their seats a bit and shim the springs an equal amount. Another option might be building up the damaged section and machining back to standard thickness. Higher-end machine shops sometimes have facility for this kind of repair. I would suggest a bit of clay to set things up again as far as clearances go... Replacement Indian heads that do match originals pretty close are readily available.

dieselgman

[Amarbir[India]]

20 thou maybe no problem at all... but 40 to 80? That is a bit drastic as far as changing the valve geometry. The head probably will have enough thickness in most cases but you will have to adjust everything for proper piston "bump height" (clearance to the head) and also valve clearance. At 40 to 80 thou you would most likely have to sink the valves in their seats a bit and shim the springs an equal amount. Another option might be building up the damaged section and machining back to standard thickness. Higher-end machine shops sometimes have facility for this kind of repair. I would suggest a bit of clay to set things up again as far as clearances go... Replacement Indian heads that do match originals pretty close are readily available.

dieselgman

Boss ,
     A Question Have You ever Come Across Any Indian Manufacturer Who Makes Near Perfect CS Type Head ? . BTW Anubis Can You Not arrange a head for the lister cs .should not be expensive .

[dieselgman]

I'm not sure I understand your post Amarbir.

Of course the Indian replacement head would likely be inferior to a Dursley original in casting... this does not mean they do not match or cannot be "doctored" to be a close replacement if availability and cost were significant factors. Original heads? Where do you think that would be available? Perhaps taken from another old engine would be an option we did not mention yet...

dieselgman

[listerdiesel]

Water corrosion of the head face is very common round the cylinder diameter, but that's not going to cause any problems, so leave it as it is.

If the gasket face is corroded then that is another matter.

Peter

[lendusaquid]

Grind your valves in for a good fit and then measure how far down they are from the surface. You will probably find them further down than the specs advise they should be after many years of work. In which case after measuring you will know how much you can skim of the head.

[rleonard]

See this thread;

http://listerengine.com/smf/index.php?topic=2990.0

[contaucreek]

I had my head resurfaced after a crack repair. You need to ensure proper valve recession as other have stated, going by memory .055-.100 thou....verify that though. Your bump height will not change one little bit regardless of how much you take off but if you dont adress the valve depth or forget to back off the valve lash and readjust then you are gonna have a crash brother !!!

[38ac]

All good information here. One thing that needs mentioned when addressing valve clearance is that you also need to make sure your OK with the valve lifter  or decompressor turned under the lifter.  In my experiance, it is more critical critical on the higher RPM engines than the 650 RPM versions but my experiance it admittably limited  @ two of the higher putput versions.  My 24/2 Powerline was sent out with both exhaust vlaves hitting the pistons HARD with the lifters engaged.

[contaucreek]

  My 24/2 Powerline was sent out with both exhaust vlaves hitting the pistons HARD with the lifters engaged.

Indian engines are assembled that way to ensure they didn't forget to install the con rods