Hallam Engine

Hi, just a few thoughts. while I was turning up some cylindical squares.

First try reducing the oil ratio down to 10%-12%, it seems to have an excess of oil or fuel dripping out of the exhaust, that could be put down to a bad air to fuel ratio,

Second idea, is that in the early years small manufacturers had to cut costs some how,

Getting the machineist to make there own needles was expensive, so was buying box's of sewing needles, but there was a big supply of gramaphone needles, unfortunately most makers had different shaped profiles and tapers,So if a hobby model engine maker took one off there own record player, it was a hit an miss affair, The other problem was that 50 years ago, small drills were not the same strength and quality that we have now, and if the home machinist had a worn or badly sharpened drill, if drilled from the needle side of the tube, bell mouthing could occur, As an example put a washer over a morse taper, pull it back, say 20mm and see what the air gap is, then put it in another morse taper, pull it back the same amount, and you will see a much bigger air gap. coupled with a miss matched needle, you now have a hard to tune engine.

So, make a selection of needles of varying tapers, clean up the needle seat, and see how that goes.( MEN has articles on makeing needles and tubes), You need a combination that will allow the coarse needle adjusting screw on your engine to work properly, ie, at least two to three turns of the screw,to get from from low revs to nearly full rev.

I saw an article on making needles, useing the right diameter piano wire, just by fixing one end solid, using pliers or a rod, on the free end and then  heating the the section to be tapered,with a gas burner pulling and stretching the wire to get the right taper, then cutting out the section you needed.

Hope this is some help.

John Holloway

Stirring me grey matter from 50 or so years ago when points and coil was the standard car ignition I seem to remember that this increase in voltage can cause an ignition coil to fail internally and stop it generating a spark. I believe that this can also be applied to the spark plug itself where the actual spark then doesn't go across the plug tip but arcs over elsewhere in the body of the plug. Another possibility is that the capacitor might be failing of have a poor electrical contact with the earth of the coil, again a faulty capacitor can cause a loss of spark.

Edited By Martin W on 10/03/2010 16:26:22