Hot Rods Stromberg 97 tuning ( AGAIN)

Hi all Hambers
I'm struggling tuning my carburetors on my flathead, I'm using the O2 sensor, I have perfect idle mixture ( 13.8 to 14), and also very good at wide open ( 12) . BUT, when cruising I'm way too rich ( 9), plugs are fooling after 200 miles...

I have try change the main jets, it is better but I'm loosing power at wide open and get a bit lean...

Can someone assist me ? should I play with power valves ? how to play with the middle circuit ?

thanks for your help

 

have you talked to Clive at Stromberg? He is usually very helpful.

 

Clive is indeed helpful, unfortunately no answer on this...

 

How many carbs are we talking about and are you using progressive linkage? I was having a very similar issue on mine a while back. I cured it by adding progressive linkage and dialing down the fuel pressure to 2.5 pounds.

 

PM sent Pierre

 

It is a stroked 284 flathead with Shneider 270F ( 395 lift) , scot blower with 2 big 97. direct linkage