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Does the team think?

Gentlemen,

A consensus of opinion from the learned is required.

I am building a half scale 'economy' (Hercules, Jaeger, Sparta etc, etc) open crank. The engine has the conventional drip feed oiler arrangement feeding oil through the liner to the piston. The little end bearing/gudgen pin is oiled via a small hole through the little end of the con rod and its bearing.

Now the opinions required bit: do I provide a hole in the piston skirt to allow oil through the skirt to the little end or do I do as the drawings say and not provide the oil path? I've seen engines with and without oiling holes through the piston skirts but have no experience of the common practice on engines of this type (pulling my Amanco or Fairbanks apart to find out is a last resort you understand).

My take on the matter is to be safer than sorrier and drill the oil path, does anyone know why this is not a good idea?

What does the team think?

Mark

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Reply to
Mark_Howard
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All I can say is that my Bradford O/C has a feed hole in the piston as does my small unknown O/C. On the latter, the hole doesn't line up with the little end and has short swan neck shaped piece of tube to bridge the gap.

nickh=== Posted with Qusnetsoft NewsReader 2.2.0.8

Reply to
nickh

I would say that, if the bottom of the skirt goes far enough up the bore to be past the hole where the oil comes in, there is no need for the feed hole and the oil will find its way to the little end. If the skirt is long and doesn't uncover the hole, a mating hole (possibly with a feed groove as per a bearing, or even a countersink style chamfer) in the piston would help. You could always put a separate feed pipe to the little end that protrudes from the skirt so you can give it a shot with the oil can before starting?

Regards

Dan

Reply to
Dan Howden

n> All I can say is that my Bradford O/C has a feed hole in the piston as n> does my small unknown O/C. On the latter, the hole doesn't line up with n> the little end and has short swan neck shaped piece of tube to bridge n> the gap.

Just nipped out to check I'm not talking c**p - no chance! The 'swan neck' is actually nearly straight and is probably there to ensure that any oil making its way through the hole actualy drips on the little end rather than running round the inside of the piston. The Bradford has a boss inside the piston which serves the same purpose.

n> nickh=== Posted with Qusnetsoft NewsReader 2.2.0.8

nickh=== Posted with Qusnetsoft NewsReader 2.2.0.8

Reply to
nickh

Thanks Chaps,

Actually, the piston does travel far enough to expose the oil drip so the oil will probably get inside the skirt and up to the little end but I have doubts as to its effectiveness due to the shape of the piston interior.

I think I will go with Nick's suggestion that a hole in the skirt and a tube feed to the bearing is a fairly common arrangement and therefore will feed the piston to my drilling machine at the earliest opportunity.

Thanks again.

Mark

Reply to
Mark_Howard

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