This may only address part of your symptoms, but I thought I'd pass it
along (only applies if you have replaced the original jets with
Grose-Jets):
Several years ago, after some extensive work, my 66 B was exhibiting a
miss at cruise, at almost exactly 60mph in 4th, and at 35-40mph in 3rd.
Tried several things, but what fixed it was replacing the original floats
(with the adjustable brass arm) with the type with a solid nylon arm
(built-in), that you adjust with washer shims. It seems the resonant
frequency of the brass arms coincided with the engine vibration at that
RPM, and the floats were bouncing up and down rapidly, essentially
dribbling the Grose-Jets like miniature basketballs! Thus causing
intermittent fuel starvation. Don't think it happens with regular jets,
but...? Anyway, it's a funny story, and I swear it's true (I have
witnesses).
>-----Original Message-----
>From: Eric Kutzli [mailto:ekutzli@netins.net]
>Sent: Monday, March 08, 1999 10:03 PM
>To: mgs@autox.team.net
>Subject: Lean at cruise
>
>
>Hello everyone,
> 1974 B... at cruising speed ( between about 50 and 60) The engine seems
>to miss on light throttle going up hills... One day just as a test I pulled
>the choke out to richen up the mixture and the miss dissapeared... Idle is
>a little lumpy, and seems hard to get idle mixture from running too rich...
>engine was rebuilt 2,000 mi ago, but carbs were not... I have tried the old
>spray em with something and see if the idle changes but can't seem to find
>the problem... Idle is too rich and cruise is too lean...
--
Max Heim
'66 MGB
runs great, looks scabrous
mountain View CA
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