Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Found my first major issue today, thought i would see how i got on with the cylinder jacket and liner. 

I would like to make this a water cooled hopper type engine rather than air cooled, there is some pictures online of a lovely job someone has done on one of these engines with hopper cooling and it is very inspiring, plus after the M90 i realise these things get hot if you work them.  I don't have a real plan so drifted into machining the jacket and liner.  The plans step the liner about halfway down so the liner is trapped between the cooling jacket and crankcase, i decided to reduce the length of the step but keep the same way of retaining the liner, with the jacket holding the liner in place at the rear and a 3mm lip to hold the front of the liner allowing me to hollow out the centre section of the jacket for the water cooling.

Machining the liner went well



As did the jacket



Got a perfect fit of the liner in the jacket, more by luck than good jugement 

It was then i noticed the problem, the inside of the liner is 'supposed' to be finished as supplied, but running my finger around the inside revealed a raised flat spot where the tube was welded dagnabbit!  Another mod i had planned was to use piston rings and and aluminium piston rather than the rather odd and heavy looking affair outlined in the plans, to do this i ordered a pair of the 25mm rings that Bengs offer, and this is my problem, the bore is already 25mm so i have no room to clean up the ridge in the bore.  I don't think a hone will remove the ridge before oversizing the bore, so i either have to order another liner from Bengs and hope it is better or make a liner from scratch, any advice here would be gratefully received 

This picture does not show it too well, but you can just see the weld undercut on the right



Ade