Resurrecting a Stuart 10V Engine

[Twizseven]

Chris,

Thanks for quick reply.
Definitely getting air out of the exhaust port, and I'm 99% certain (but will check tomorrow) that when the slide valve was in the middle position that air flow from the exhaust port ceased.  I know all the actual ports within the cylinder are clear, but will check that the gaskets have not done anything silly.  Will drop the top cover of in the morning and check that air comes out of the top port as it goes past TDC.

You commented about the port opening after TDC and BDC.  At the moment when the cylinder is at TDC or BDC the ports are just open about 1/2mm.  Have I got them opening too soon.

Will do the checks in morning.

Thanks again.

Colin

[crueby]

Yes, that is too soon. If the ports start opening before the end of the stroke, it will have a tendancy to push the piston back before the crank makes it around the end. If running very fast, it can get past that, but you would not be able to run slowly that way.


If the slider is not quite long enough, then the position of the eccentric gets to be very touchy to keep the port openings after the ends of the stroke. I had that on my most recent build, and wound up remaking the sliders a little longer, but in my case the eccentrics were not adjustable like yours are, so you should be okay.

[Jasonb]

I've never been a fan of the adjust until you see the port being uncovered method.

As a starting point I set the highest point on the eccentric to be 90deg plus 30deg in advance of the crank pin. and engines all seem to go first time. So provided your eccentric has been tapped with the grub screw lined up with the maximum throw put the engine at TDC and a key in the screw and rotate the eccentric until the key is at 4 o'clock or 8 o'clock depending on the direction of travel you want.

If you can't get the valve to sit centrally and half a turn of the rod is too much then cut 1/4turn more thread onto the end that screws into the fork so

Lastly make sure the valve is vertical not horizontal as I've seen that done a few times the longer 1/2" edge should be vertical. And make sure it is not sticking on the nut and failing to seat properly. Drop of oil into the valve chest before running also helps.

[pgp001]

Colin

Are you sure you havn't got any leakage behind the now port block insert ?
If the block does not make a perfect seal on its back face you might be getting some pressure losses in there.

Phil

[Twizseven]

Success.   

It needed a few changes.  I was happy that the seal of the new port block was okay although I take Phils's point it could possibly have been a problem.  When I put the JBWeld it I had ensured that it was forming a complete ring round each port.  As per Chris's suggestion I took the top cover off to be able to check getting air and the slide valve working okay.  Getting air quite happily whilst piston at TDC and stopped once piston down towards BDC.  As soon as the lower port opened I was getting just as much air as from the top port but in this case it was coming round the piston.  I knew it was a bit loose but not quite that bad.  Tried a 3/4" reamer in the bore and it fell through.  Tried a telescopic bore gauge and had a bore of 19.332mm and not only that it tapered from one end to the other.  The piston was extremely loose. The only way I could fix the bore was a 23/32" - 25/32" adjustable reamer.  Eventually ended up with parallel bore at 19.43mm.  New piston turned, lapped briefly to ensure reasonable fit and clear a slight high spot in centre of the bore and then fitted. 

When I re-assembled the engine I checked the slide valve and by rotating 180 degrees I had an equal opening of top and bottom ports.  Then went with Jason and Chris's comments regarding opening of the ports.  Put to TDC and rotated eccentric so that port did not start to open till piston over TDC.  Finished re-assembling and put some air in.  It started immediately.  After 5 minutes stopped it and disconnected the air and squirted a bit of oil down the inlet.  Started it back up. Now after about an hour with stopping it every 15 minutes of so for oil I have got it running very slowly on about 4psi.  Really pleased.

Out of interest how do you normally add oil when running on air.

I can now start to make the reversing gear.

Thanks for your help guys.

Colin



[youtube1]https://youtu.be/kfpepeXiKTo[/youtube1]

[crueby]

Excellent!!   

[AOG]

Out of interest how do you normally add oil when running on air.

I use a dedicated air hose with an in line dryer/air tool lubricator. It works really well.

Tony

[Twizseven]

Tony,

I did wonder about that.  In fact my air supply at the present comes out via a pressure control/dryer and an oiler.  That hose is then going to another regulator/dryer/oiler (but in this case no oil as I think the internal oil pipe is broken)  then via a foot operated air switch up to the engine.  Currently the air switch is clamped on via a pair of mole grips.  The engine is running away in the workshop, running itself in, whilst I am in the warm office.  I will try and find some info on the oiler to work out what is missing/broken.  It may just need a pick up pipe to work.

Colin

[AOG]

On mine there is a little adjustment screw that you set to regulate the amount of oil going through. The lower the pressure in the line more to have to open the screw in order to get it to feed.

Tony

[Twizseven]

Had it running for at least hour and half, loosened up amazingly.  Just done a run with pressure control turned to zero and air valve on manifold half shut.  It was running really slowly.

[youtube1]https://youtu.be/4fBWskn7l2g[/youtube1]

Colin

[scc]

That's running nicely      Terry

[Twizseven]

Terry,

Thank you. Just stopped it for the evening.  I am amazed at how easily it spins now compared to when I first started it up couple of hours ago
Colin

[Kim]

Congratulations!  That's really running well! Glad to see you got it all sorted and it running so beautifully 
Kim

[Admiral_dk]

You must be very pleased with the result - especially after your tribulations with it - and nice to see that it payed off