Mamod upgrade cylinder and upgrade piston kit
Posted: Fri Aug 26, 2011 8:42 pm
As many of you will know mamod cylinders are not the best bits of engineering so most are usualy upgraded. There are two options, the full upgraded cylinders or the piston upgrade kit which only changes the vital parts. Below is review and comparison of both items of both items.
Starting with the upgrade piston kit. The kit contains new front and rear ends for the cylinders, the rear one having an adjustable gland machined onto it, new rods with the O ring piston and stronger trunion springs.
Fitting of the kit is relatively simple, though getting the O ring into the cylinder needs care. The big ends need to be removed from the old piston rods and fitted to the new ones making sure that the gland nut and its O ring are on first. As for the stiff springs i have left them off as I found it clamped the cylinder to the port face and severly limited performance. Running in takes about 4 or 5 runs untill you can run the loco on the track.
Next are the full upgrade cylinders which are a direct replacement for the originals.
On my cylinders I has to do some cleaning of the ports as there was still swarf from the machining in the holes. The second thing i did was take the stiff springs out and replace them with the softer ones. the reason I did this is because even after lapping the mating faces were still quite rough and the stiff springs nealry locked the cylinders solid. Running in didn't take long for the actual O ring in the cylinder but has taken a long time for the faces to stop leaking. With the soft springs in the engine is useable while running in takes place and after they are bedded in the stiff springs can be put in to get the full power from the cylinders. As for which to buy I cant come to a firm choice as each seem to work equaly well and both make the engine more efficient once run in fully. Ive put a couple of comparison pictures below. If you made it this far thanks for reading.
Starting with the upgrade piston kit. The kit contains new front and rear ends for the cylinders, the rear one having an adjustable gland machined onto it, new rods with the O ring piston and stronger trunion springs.
Fitting of the kit is relatively simple, though getting the O ring into the cylinder needs care. The big ends need to be removed from the old piston rods and fitted to the new ones making sure that the gland nut and its O ring are on first. As for the stiff springs i have left them off as I found it clamped the cylinder to the port face and severly limited performance. Running in takes about 4 or 5 runs untill you can run the loco on the track.
Next are the full upgrade cylinders which are a direct replacement for the originals.
On my cylinders I has to do some cleaning of the ports as there was still swarf from the machining in the holes. The second thing i did was take the stiff springs out and replace them with the softer ones. the reason I did this is because even after lapping the mating faces were still quite rough and the stiff springs nealry locked the cylinders solid. Running in didn't take long for the actual O ring in the cylinder but has taken a long time for the faces to stop leaking. With the soft springs in the engine is useable while running in takes place and after they are bedded in the stiff springs can be put in to get the full power from the cylinders. As for which to buy I cant come to a firm choice as each seem to work equaly well and both make the engine more efficient once run in fully. Ive put a couple of comparison pictures below. If you made it this far thanks for reading.
