Finished my Stuart Turner #1. Bought the castings second hand in 1996, They were initially bought in the late '60s or early '70s, and when I got them they had been through 2 or 3 (or more) owners. Everything was there except the rings were broken. Finally got around to starting it on 5 Oct. last year.
Have run it on air for around an hour to run it in and it now will run down to 12-13 psi. The rings are producing quit a bit of friction in the bore. I noticed that at the slowest speed it runs quite unevenly. After a bit of head scratching and watching it was apparent that it was slowing down over TDC the once about 30 deg beyond it would speed up down and over BDC only to slow down again approaching TDC.
So as an experiment I removed the rings and the piston rod packing and found it turns over extremely freely (the piston has about 2-3 thou clearance in the bore). When turned over slowly by hand and the piston gets to about 20-30 deg after TDC it rotates by it's own weight down to BDC, slightly beyond then back to BDC. So it would appear that the slow speed unevenness is due to the fact that there is no counterbalances on the crank to compensate for the reciprocating mass of the piston, rod, crosshead and con rod. Might look at fitting some in the manner of the ST#5 as an experiment.
John
Edited By John Purdy on 16/08/2019 19:32:52
Edited By John Purdy on 16/08/2019 19:36:11
Edited By John Purdy on 16/08/2019 19:41:39