Yesterday I went for a test ride after installing a "original" timed breather AND removing all the other attempts I had made at breathers.
Before I installed the timed breather pinion I modified it as recommended by PEI in MPH 252 [thanks for that tip, David]. I also modified a spare banjo I had to improve the flow rate through it. Using kneadable epoxy I fitted a short length of 1/2" OD copper pipe over it and once all was set I then drilled out the outlet tube of the banjo. opening it up by a good 50%. I attached a length of 1/2" bore hose to the banjo, running it up under the seat then down into a catch can (actually an empty clear plastic drink bottle).
For the record, the slot in the breather spindle is facing DOWN in my motor; Using a series if files I opened up the slot in the breather bush to a full 3/8" wide , made sure it had a knife edge in both edges then blended the two edges of the flat into the circular portion with a generous radius, finally I fired up my bench polisher and brought the breather bush to a mirror finish. I installed the breather pinion assembly using a timing disk and a length of hose connected to the breather outlet (for me to blow through) so I could determine exactly where the breather was opening and closing - I ignored the marks on the pinion itself. I set the breather timing as follows: Opens at 22 degrees ATDC and closes at 3 degrees BBDC.
I started the motor and let it idle for 10 minutes before I set off - all that I observed in the catch can at this time was a bit of condensation on its inside walls.
After a 70 mile run at varying speeds of up to 72 MPH, that also included some long stops waiting at traffic lights with the motor idling , and at least two (intentional) motor stops then restarts I returned home and checked the catch can. It contained no more than 20cc of milky looking oil. On checking the oil tank, the level seemed to be the same as it was before I set out. This was amazing , as prior to this, a run of this length would have needed me to add more than a 1/2 pint of oil to restore the level in the oil tank.
This morning the oil in the catch can was still milky so I assume it is an emulsion of oil and engine condensate, this is important to note for it means that the oil from the catch can is contaminated with god knows what should NOT be returned to the oil tank.
Those of you who have followed this thread may well wonder why I bothered with an alternative breather. When I got my Comet a prior owner had made a number of "changes" to it, in part I think, in an attempt to bring it up to "D" specifications. One rear brake had been removed, both wheels had been rebuilt - the front with a 19" rim and the rear with a 18" rim, all parts of the timed breather had been removed, the magneto had been removed, the original generator had been removed, and replaced with a strange unit that incorporated a set of points allowing a Kettering ignition to be bodged up, , an "elephant trunk" style of breather had been installed behind the front cowl using the opening where the magneto should have been - the list just goes on and on. Over my 2 years of ownership I have been working on getting all back as it should have been though I have left the wheels alone as they allow me to use modern tires - (Michelin Pilot Active tires are great!).
Sorting the breathing was about the last item on my list of things to resolve. To all who have persevered with me on this journey, providing guidance, comment and assistance, I thank you.
Martyn
