Rich mixture? Elan+2

[Mrozik]

Hi All

I was wondering if the members could suggest other possibilities that could cause the following problem.

Since rebuilding the engine including new pistons and an overhaul or replacement of just about every component although the engine starts fine and initially runs well for 10 -20 miles. It then starts to run on 3 or less cylinders! When first started after the rebuild the engine smoked (black) quite badly and back fired but after some carb adjustments, this has since improved...

After the problem appears, removing the plugs show that they have all become quite sooted but cleaning them restores the the engine to running on 4 cylinders again.

To my mind the problem is surely a carburation one but I don't understand why it should so bad?

The Weber carbs were serviced - no jets were changed.
I intend to check the float levels but I was wondering whether new jets might also be required now that the engine is "new"?

The mechanical petrol pump was serviced - could the pressure be too high now?

A new distributor. HT leads and coil were fitted and they seem to work well - however as meanwhile I've converted the old distributor to electronic ignition, I was wondering whether fitting this, thus strengthening the spark, might solve or improve matters?

I have check the cylinder compressions and they are all between 165 and 170 psi so mechanically fine!

Is there anything else I should check?

Thanks in advance

[EPA]

Sometimes the cold start device(choke) isn't completely closed which can have this effect. Try pushing them both closed and ensure that the cable adjustment is not holding them open.
Ed