HOME and how to join Forum Open Area General Scott topics Gugeon pin removal Re: Con Rods

Roger Moss

Hi Mike. The original design of Alfred Scott was gradually stretched so that the line of the big end is usually not on the centreline, but a bit wider.
Long stroke rods, if you look at them carefully, are not milled symetrically, but are a bit off centre. The idea was that the centre beam section should not rub against the flange of the crank, so they tried to leave a bit more clearence one side (The inside) There is not a big difference and as long as your rods are not rubbing on the crank as you turn the engine over, it actually does not matter which way they are installed.
If you wanted to turn the rod, you must undo the crankpin screw, remove the outer roller plate, take out all the rollers (A small magnet is helpful).
You must then rotate the flywheel so the rod is at the top of it’s stroke.
If you look down the crankcase mouth (naturally you have the barrel off) you will see two cutouts on the outer side. This is like a “Lay by” parking place for the rod. Hold the rod in these cutouts and again rotate the flywheel to take the crankpin past the “parked” rod. You can now remove the rod. Please note that it was once a traditional practice to replace a rod little end bush, ream it in position and then bend the rod between three pieces of aluminium in a vice to get eyeable alignment with the big end. Twist was dealt with by twisting the rod beam. Unfortunately, this practice rarely resulted in good enough accuracy and often engines would not survive more than 1000 miles. I mention this, as there are rods in use that have been bent so the maximum clearence might not be on the side with the dot.
The obvoius and best test, is to place the rod big end on a flat surface with the little end hangine over the edge. Now look how much space there is under the centre of the rod beam. Now turn it over and check the space under the other side of the beam. Build your engine with the side with largest clearence towards the flywheel. The gudgeon pin is always fitted with the big end to the outside, as this prevents it sliding out into the inlet ports. I hope this helps. Kind Regards Roger Moss