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RWD - SU Guru needed. B20 Lean Stumble

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SU Guru needed. B20 Lean Stumble 120-130

SU Guru needed - Lean acceleration.

B-20 w. Hatachi SU's ( Japanese copy of the Euro SU's)
I've been through all of the tuning guides but am missing some link..
I have a WBO2 installed and am getting...

Idle @ 850 rpm 11.7:1 to 12.2:1 AFR
Cruise @ 40 mph 14.5:1 to 16:1 AFR
Hard acceleration 10:1 to 11.8:1 AFR

So far so good. But...
Slow acceleration or going up a hill, leans out and pegs the WBO2 above 17:1 AFR
and exhibits serious lean stumble.
I've tried several different weights of oil in the dash pots, everything from no oil at all, ATF, 20 wt, 30 wt and 20 wt mixed w. 90 wt gear oil. The heavier oil works better, but doesn't cure the problem.
I've also tried richer (HG) needles but still get the same result. Though the richer needles seem to give more power before it all goes to crap around 3500 to 4000 rpm.

I've checked for leaks (carb. shafts, manifold and everywhere else)
Confirmed the timing (12 degrees BTDC)
Adjusted the float levels
Good compression (165,165,160,165)
The carbs. are well balanced, clean & the needles drop as they should

The various information on tuning seems to say as long as your idle mixture is good, then the rest will just sort of fall into place.
Certainly not my experience.
So, where am I going so wrong?
Any and all suggestions welcome.

Thanks
-TR

 





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New 1 SU Guru needed. B20 Lean Stumble [120-130]
posted by  TR Conn  on Tue Mar 6 01:19 CST 2018 >

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