Saving Old Seagulls

Silver Century Gull with the twin-jet Amal carb. Everything is fine after full clean from tank to jets. The jets are positioned correctly (short closer to block intake as per Amal diagram). Jets cleaned again and filters checked. Motor starts OK and runs great but one small tweak required I think. Up to half or 3/4 throttle all good , but once the throttle is opened fully there is not much difference in revs or exhaust note , and revs tend to waver slightly up and down between full and 3/4 throttle or so. It feels almost as if it is "starving" for fuel at high throttle setting. When you reduce throttle from full throttle back to 3/4 the revs tend to settle back nicely and wavering stops. All fuel components have been cleaned 4 times and everything looks OK. I am starting to wonder if is electrical ? but highly unlikely. I havent changed the plug yet , but will do so anyway. Also just wondering , the fuel hole in the bottom of the float chamber arm - should this hole in the arm - ideally line up with the holes/s in the banjo bolt in the float chamber.? Or this there sufficient clearance by design for the fuel to wrap around inside the arm cavity supply.? I cant see how this would ever be possible to match these up anyway ..

If you remove the choke? Maybe it's a sign of the engine running with more fuel than it needs. After all it's not good running it on full throttle all the time.

Do you mean remove / unscrew the choke hood ? Usually constant running between 3/4 and full throttle has never been a problem ... always purred along nicely ..

The banjo bolt is as it should be and it doesn't sound like you have a fuel problem, more likely your getting to the maximum speed of the motor at 3/4 throttle, have a look and see if your points are set correctly.
Are you running it in a tank or an a boat?

rabbit wrote:Do you mean remove / unscrew the choke hood ? Usually constant running between 3/4 and full throttle has never been a problem ... always purred along nicely ..

Yeap, remove the hood. Running in a tank may be a matter as Keith spotted.

I should have updated my previous posts about my uneven running in a tank ...answers and replies to my earlier posts were exactly correct thanks to all. Yes - cavitating in a tank amongst other things was the problem. Now that I have the motor on the boat , all is well - apart from the issue encountered here with 3/4 to full throttle variance. I will clean and check the points as well then thanks.
Any other suggestions welcome.