COV WTF??

[richardhula]

Maybe we have an answer! Looks as if it may be an internal COV part from an air start system on a JP2 or JP3
Have a look at these links: the third link shows a JP2 with air start valve in the lower right which is plumbed into one of the COVs.
I wonder if one could use this to start a single cylinder engine?
Cheers,
Hugh

http://www.ebay.co.uk/itm/GENUINE-LISTER-JP-JK-JS-ENGINE-2-3-4CYL-AIRSTART-C-0-AUXILARY-PLUG-011-03306-/251228735725?pt=UK_BOI_FarmingEquipment_RL&hash=item3a7e6648ed

http://www.ebay.co.uk/itm/GENUINE-LISTER-JP-JK-JS-ENG-2-3-cyl-AIR-START-VALVE-ASSY-573-10940/251279039315?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D24931%26meid%3Dbfe4a5d519544177851de4805ad8a5f1%26pid%3D100005%26prg%3D10513%26rk%3D1%26rkt%3D6%26sd%3D251229037498&rt=nc

http://www.oocities.org/tonniduekpics/

Well spotted - seems like an answer - see below on parts diagram for air start valves on JPM particularly part #24. Air start procedure is to open this COV only leaving other(s) closed.

[Blue]

I ran a JP 2 for years and it had the convex face. When screwed in it would seal against a face and when screwed out the back side would seal against another face to stop exhaust fumes leaking up the threaded shaft. It was a hand start unit. Worked well.

                                                                                                             Blue

[Hugh Conway]

I ran a JP 2 for years and it had the convex face. When screwed in it would seal against a face and when screwed out the back side would seal against another face to stop exhaust fumes leaking up the threaded shaft. It was a hand start unit. Worked well.

                                                                                                             Blue

Thanks for that, Blue. So it was a real Lister part, just one we are mostly not familiar with. I may have to just try that rather than use a standard COV.

Because:

I have tried to remove the "main plug".......the concave part that fits into head.......no joy. Used the wooden plug method, but it would not come free. Even though a bit of oil squirted  caused the engine to fire. Repeated this a few times, but the plug would not free up.

I put a bit of clay into the Main plug stuck in the head and also into a normal main plug that came with a new COV. Molded to shape, the dimensions are easily seen to be different. The new, normal main plug is about 1/4" shallower than the unusual one in the original photos. Looks as if the main plug part is specific to the type of COV.

Any one have some alternative ideas for removing a reluctant main plug?

All suggestions welcome!
Cheers,
Hugh

[mygoggie]

Here is a comparison of COVs
I am having a bit of confusion here. Two different looking COVs.
One (red handle) came out of my Dursley 6/1 Startomatic.
The other (unpainted) is an Indian replacement.
The Indian COV looks like the ones in both the original and Indian parts lists. The other, I have not seen one like it. The business end is concave on the Indian and in parts manuals, but the other is convex with the valve seat recessed way inside.
Has anyone seen one like the painted convex unit? It is unlike the other and unlike the ones shown in parts manuals. They both fit into the Dursley engine, but I will bet only one will work.

Any ideas/ input will be appreciated.
Cheers,
Hugh

I would like to know the outcome of this problem, as I had the same astonishing discovery when I pulled the COVs on my 12/2. The one COV is convex and the other is concave.

[Hugh Conway]

Tried all the suggestions to remove the "main plug" without success. The recommended wooden plug method, drilling and threading to use a bolt as puller, heating. All did not work, the plug was stuck tight.
Eventually I pulled the head, took it to a machine shop and had it carefully cut out. Made a couple of cuts and collapsed the plug. It was apparently just really stuck with accumulated carbon.
The proper main plug and COV fit right in. Re-installed the head and fired it up.
Cheers,
Hugh