Small end clearance

Hi Yuri,

The only info I can find on gudgeon pin to small end bush clearance is in "Tuning for Speed" by P E Irving. He suggests a minimum clearance of .001 inch (for racing engines), and specifically for Norton, a maximum of .005 inch.

If you fit a new small end bush to the con-rod it will compress, so the final adjustment of the clearance has to be done after installing the bush. This can be done with a 3 leg hone, or possibly an adjustable reamer.Remove only a little material each time and keep checking the fit of the pin. You want it to slide easily into the bush, but with barely detectable side to side movement.

Be careful - you can easily remove material but you cannot put it back!

Hope this helps

Ian McD