Building the twin cylinder 7BIM engine.

No, even when I was running it on one cylinder at a time, both sets of pistons and valves were connected to the axle and flywheel with their eccentrics and cranks so the amount of friction is still the same.

I think I am losing much more air than I first thought. Tomorrow I will try sealing all the pipe work with either plumbers tape or Loctite 567.

Well all the pipes and joins have been sealed with Loctite 567 and I used plumbing tape on the tube union but it has not made much difference : the engine still only runs on for 5 revolutions after turning off the compressor whereas before it would run on for over 15 revolutions. I guess it is what it is ! But I am surprised that adding the manifold, lubricator and globe valve has resulted in such a loss of pressure in the system. Now I can see why many people prefer to solder the pipe work.

Note that a similar thing has happened with the single cylinder 3BIM engine : before all the piping was added it would run for over 20 revolutions after turning off the compressor but now it only runs on for 7 revolutions.

Edited By Brian John on 17/10/2014 04:58:22

Edited By Brian John on 17/10/2014 04:59:35

Try it without the exhaust pipes fitted.

I have and it makes no difference.

UPDATE : I have given the smaller 3BIM engine a full 48 hours for all the sealant to harden and there is now a real improvement. It will run on for about 14 revolutions now. There is no oil leaking from around the pipework ; only oil leaking from the exhaust pipe so enough oil must be getting through to lubricate the cylinder and piston. The only air I can detect leaking from anywhere is a small amount from the bottom of the displacement lubricator. I suspect that this is normal function because there is no oil leaking from there hence nothing more to be done.

I will give the larger 7BIM another 24 hours and try it again.

Is it possible that some sealant partly blocked the airways and has now blown through.

Neil

7BIM update : I have checked the cranks on the 7BIM engine and they did not look like they were set exactly 90 degrees to each. After a slight adjustment the engine will run on for 12 revolutions. This is a big improvement. I may have to check the valve timings too. What was not crucial when running the cylinders independently is very important once the two cylinders are connected via the manifold.

3BIM engine ; I have altered the valve timings slightly and this single cylinder engine will now run on for over 20 revolutions. That is very good. There is still a slight amount of binding at BDC. Sometimes it is there and sometimes it is not so I am a bit puzzled. I might have to fiddle a bit more with this.

Brian, re the binding at BDC is there perhaps a little moisture in the cylinder, either oil or water, that might explain why it's not always there.

Ian S C

Edited By Ian S C on 21/10/2014 11:56:54

That could be ; I will look into it.

1. But isn't there supposed to be steam oil in the cylinder ?

2. The 7BIM twin cylinder engine only drops steam oil from the exhaust farthest from the displacement lubricator. I would have thought steam oil should be exhausting from both cylinders. I am puzzled why there is no oil coming from the exhaust on the cylinder closest to the lubricator. It does run nicely though .

Edited By Brian John on 22/10/2014 05:39:47

1. Only a smear you don't want it building up and causing a hydralic lock. Infact as you are running on air you really don't need steam oil as at room temp its a bit thick and sticky try changing to a lighter weight oil and it should run even smoother

2. Suggests one cylinder is working more than the other and the valve timing may be different between the two. If anything the more direct route is to teh cyl nearest the lubricator so you would have expected more oil there is anywhere

Edited By JasonB on 22/10/2014 08:45:33

2. Not long after posting that question I noticed some oil drops under the other exhaust pipe so everything must be working fine now.

With the oiler off centre, initially you would get uneven oiling, but once the oil is through both sides it will be OK. Sewing machine oil is quite good. 3 in 1 oil is similar to WD 40 in that it tends to gum up the works.

Ian S C