Gurus, I need some help with my Webers. I have a matched pair of 151s
with the following configuration: 55F8 idle jets, 1 1/2 to 1 3/4 turns
on the idle mixture screws, idles nicely at 1K RPM with ~ 1/2 turn on
the idle speed screw. Accelerator pump jets are 40s, the pump exhaust
valve hole soldered shut (the ball valve still works). Main jets ranged
from 150 to 120, with various combinations of air bleeds from 150 to
190. The plastic float levels have been set to 14.5 and 22mm, to reduce
fuel in the well. The problem is that above ~2K RPM the AFR drops to
high 10, low 11, so of course the engine runs like crap. One more bit
of info: fully closed the throttle plates are mid-way in the first
progression hole. One Weber parts distributor said that was correct for
151s, another said that the carbs must be binding because the
progression holes should be clear at fully closed throttle. Hmmm. The
throttles have no binding that I can feel (linkage disconnected).
I took a set of main jets and filled the fuel hole with JB Weld,
thinking I'd start really small and work up. As a baseline test I made
a run with the hole still closed and the AFR was still ~11.5. Ah ha!
That tells me that it's not the main circuit which is the problem but
rather the accelerator pump circuit. I noticed that at 2100-2200 RPM a
ball of fuel forms on the jet, then drops into the venturi; that seems
wrong to me, but I've not found any info in a myriad of Weber books on
what might be wrong in the accelerator circuit .
Falling back on my Army career, I'm tempted to implement my mantra that
"there's no problem that judicially placed high explosive can't solve".
Before I start shopping for C4, anyone have any ideas? Any and all
advice gratefully accepted.
Tnx!
jim
--
Jim Hassall
Blacksburg VA
'63 TR4 in autox preparation
99% finished, 90% to go
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