Misfire on 73 Bonnie

As for the carbs - which side was the one you sent back ? left by chance !! (could you not have received two duff one's from the start)

 

Could be over fueling ? sticking carb float or wrongly adjusted,
just throwing out a few ideas, I'm sure others on here will help more when they see your post

 

Have you set the float levels

 

Factory says 2 n 4 thou but 3 inlet and 5 ex work better Floats should be 5mm down from top of bowl

 

What ignition system do you have, old points system?...old Lucas E.I.?...or Boyer. or Pazon E.I.?
If old points system, it could be a faulty capacitor or the right side points are shorting to earth or cable going O.C. (sometimes the flexi cable that fixes to moving point breaks down with fatigue).
If you have old Lucas E.I. the control units have a habit of "drifting"
With a Boyer or Pazon fitted timing will be correct on both cylinders, as it works on "lost spark" principle, and of course there are no capacitors.
With the points system you have possible slight variations in timing due to points gap and points positioning.
If you do have points and capacitors, the first thing I would do is swap the capacitors to see if it transfers the fault to other bore, as you did with carbs.
Graham

 

"Wassell" could be your problem. They supply pattern parts.
Always get your carbs direct from Amal or from Surrey Cycles.
Valve clearances should be 2 and 4 thou.

 

Also look up the Amal website. It tells you how to set the float height correctly by moving the brass float needle seat in the float bowl. 5mm is too low.

 

The reason I am suspecting ignition as opposed to carbs is, I had the same symptoms on a 1980 T140E with Lucas E.I.
It turned out to be "drifting" on the timing and also had a faulty capacitor.
Fitted Pazon E.I. and dual outlet coil, and it now runs as smooth as a smooth thing all the time

 

But...also agree it could be float levels or float level cut off needle/seat leaking....which would account for it running better when you turn fuel off for a while.

 

Just make sure that after you have fitted the clutch you turn the engine over and adjust the springs so as the clutch unit is not wobbly, remove cable from bar end and then slacken off lock nut, screw in adjuster rod until plate lifts, back off a little and tighten nut.