Engine set up dellortos running rich

[NYK]

I’m running up my engine since a complete rebuild the carbs also have been stripped cleaned and assembled with new seals gasket accelerator pump diaphragm. I have a 4 tube manometer on the carbs and they are reasonably well balanced. Was using colourtune plug to set the idle mixture but have reverted to observing colour of plug to get an initial starting point.
Basically No. 1 and 3 are running very rich, plugs coming out black/sooty. I started with the idle mixture screws at 2½ turns unscrewed from fully closed and by now they must be 4-5 turns open but still No. 1 and 3 are coming out sooty.
Any ideas?

[steponit]

Get yourself a Gunson colourtune, so simple to use. You can see what you are doing with it.
Just adjust for blue.
Regards
Steve

[NYK]

Get yourself a Gunson colourtune, so simple to use. You can see what you are doing with it.
Just adjust for blue.
Regards
Steve

Yes I have one and was using it but clearly 1&3 are miles out (too rich) that I’m not in the region where the colourtune plug would be useful.
The point I was trying to make is that the two cylinders running rich have their mixture screws a long way “out” from where the book suggests the setting should be, much further unscrewed than 2&4. So I’m wondering what else might be causing this very rich running on those two cylinders. Unless it is normal to have to really back off the idle adjusters.

[mbell]

Isn't screw out = richer? (it is on webbers)

If they are rich at 2.5 turns out you should be screwing them in not out. Screwing it out just makes it richer.

[NYK]

Isn't screw out = richer? (it is on webbers)

If they are rich at 2.5 turns out you should be screwing them in not out. Screwing it out just makes it richer.

Your dead right! Having re-read the tuning guide I found, clockwise weakens. Shame I didn’t read it properly in the first place and I could have saved half a day wasted!
Thanks

[elans3]

Agreed as above, in to weaken, out to richen. Also, don't get hung up on each screw having to be exactly the same amount of turns out. Once the engine is warm (at least until the thermostat has opened), set the idle speed at around 900 - 1000 rpm. then screw each air screw individually in or out until you achieve the highest idle speed. Return the idle speed to 900-1000 rpm. Repeat on each of the other screws until you achieve the highest idle speed on those, each time afterwards returning the idle speed to the 900-1000.
Once you've done all 4, repeat to satisfy yourself that you've achieved the highest idle speed on each one.
Re-set the idle speed to 900-1000rpm and you're done. you will find that the airscrews will not all be exactly the same amount of turns out, but should be within a quarter of a turn.
Obviously this operation will only be accurate provided that your ignition timing & valve timing, is spot-on, and that you have no other issues like air leaks into the inlet manifold, & that the carbs are balanced perfectly before you begin.

[NYK]

Thanks, we have round two tomorrow then. Still at least I didn’t get the timing 180 degrees out.

[alan.barker]

If you do another check for mixture on tickover with the Colourtune you need just starting to go a little yellow.
If you adjust for blue only you will find it too weak and will hesitate when you start to accelerate.
Alan

[NYK]

If you do another check for mixture on tickover with the Colourtune you need just starting to go a little yellow.
If you adjust for blue only you will find it too weak and will hesitate when you start to accelerate.
Alan

Thanks Alan

[billmoore42]

I have found that my 67 Elan with Webers tends to foul the plugs if idling for extended periods. Always a good idea to start a carb tune with a fresh set of spark plugs for best results.