28-11-2020, 10:31 PM
John,
I tried your cutting ignition at high speed after a good distance so engine quite hot, although not running particularly hot in general.
Plug three always appears a very dry matte black, I dismissed oil as I would expect that to be somewhat wetter looking.
I have swapped plugs around but it is always No. 3 that is like this.
Oil consumption is very little, about 1/8" down on dip stick after about 500 miles since rebuild, rebore, new pistons rings (correct way up) etc..
Cylinder pressures are all about 100psi.
The mixture may be rich, so maybe the question is, why are the others showing weak mixture.
I have checked all joints so no air leaks.
I believe I had been running slightly too advanced, I fitted a manual control so I could check this and was able to find a good position so the engine runs quieter now, but not too retarded.
The Ignition is something I am checking but there does not appear to be any misfiring, performance is good, although I am not an experienced A7 owner. I do not recall this happening when I had the Zenith Carb fitted but had less reason to check then.
Thank you for the replies.
Roger
I tried your cutting ignition at high speed after a good distance so engine quite hot, although not running particularly hot in general.
Plug three always appears a very dry matte black, I dismissed oil as I would expect that to be somewhat wetter looking.
I have swapped plugs around but it is always No. 3 that is like this.
Oil consumption is very little, about 1/8" down on dip stick after about 500 miles since rebuild, rebore, new pistons rings (correct way up) etc..
Cylinder pressures are all about 100psi.
The mixture may be rich, so maybe the question is, why are the others showing weak mixture.
I have checked all joints so no air leaks.
I believe I had been running slightly too advanced, I fitted a manual control so I could check this and was able to find a good position so the engine runs quieter now, but not too retarded.
The Ignition is something I am checking but there does not appear to be any misfiring, performance is good, although I am not an experienced A7 owner. I do not recall this happening when I had the Zenith Carb fitted but had less reason to check then.
Thank you for the replies.
Roger
Location:- Haverfordwest, Pembrokeshire.