The engine: '75 MGB 1800cc with 9.5:1, 289/.405 cam, DCOE-type (SK)
40mm sideraught, LCB headers. Has performed wonderfully for the last
~9 months and ~10k miles (since last rebuild which incorporated
a beautiful ported & polished head from the UK along with aircraft
quality head studs == no more blown headgaskets)
The problem: uneven running/misfiring/loading under acceleration
(accentuated under *heavy* acceleration) accompanied with some
coughing back through carb while crusing. Problem hits primarily above
3000 RPM. The misfiring feels like fuel starvation. Plugs look
on the whiter side of tan. Plugs/exhaust smell fine, no hint of
over rich mixture or that "hot" smell of a lean one.
I'm out of ideas. This started after fueling up on a less than 1/8
tank full. On leaving the station I noticed a bloke with a big
dipstick checking the fuel level in their tanks.
What I've done: changed plugs, points, rotor, cap, fuel filter (the
filter in it had only a few hundred miles on it), oil and oil filter.
Points gap, float level, accelerator kick circuit, etc have been checked.
The fuel filter I pulled looked fine.
I'm considering this is a case of the convservation of MG problems,
as I did some wheel bearing work and put in autocross brake pads,
making braking nicer and tracking down some minor vibration I've
had. MG problems are not created nor destroyed, only changed in
form...
It is rather frustrating as this is my daily driver and I can think
of nothing else to check.
I wish I had everything together to put the fuel injected 3.9 in
the old beast.
Thanks,
-Keith Wheeler
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