Tuesday, 18 June 2013

Build Lubricant

One of the things I need to do in order to proceed with engine build is decide on what build lubricant to use. There are a number of things we ought to consider:
  • Different parts of the engine see different service parameters – e.g., the pistons & rings service temperature is very different to that of the main bearings
  • Loading is very different in different parts of the engine – e.g. the cams and tappets experience load through a sliding interface; the cam bearings load is experienced through rolling ball bearings with a much higher point load
  • Build lubricant ought to be selected according to the length of time between build and initial running – the lubricant needs to stay in place prior to star-up
  • Build lubricant ought to be selected according to the ambient conditions 
Casting around various personal & web sources, I came up with the following principles:
  • Pistons and rings need a special lubricant to avoid the lubricant clogging the honing marks on the cylinder walls and carbon deposits in the ring grooves. Something that burns away quickly is appropriate, like Two stroke oil or WD40
  • Consider pre-lubricating the engine prior to lighting up. This gets most of the crap from break in out because it has not had time to settle and is still suspended in the oil. 
  • Do not forget to pre-lube both ends of the pushrods too
  • Everything must be CLEAN or nothing will work properly. 
So, condensing all that experience down:
  • Engine oil for valve rockers, guides & stems 
  • WD40 for cylinders & rings 
  • Engine oil for crankshaft main & big end bearings 
  • Lithium grease for cams, tappets & pushrods 
  • Turn the engine over on a power drill prior to start up.  
  • Oil and filter are changed immediately after 20 minute initial run while engine is hot

No comments:

Post a comment