IML: 440 Surging

["Eric" <gearhead@xxxxxxxxxxxxxxxx>]

My '72 440 had a similar trouble that was solved with a new timing chain and 
sprockets. If your timing mark skips, it's well worth the trouble to do now 
before the nylon cam sprocket fails altogether. Also, the phenolic spacer 
under the carb was riddled with cracks that I could see only once it was 
fully off of the intake manifold. This is a common source of vacuum leaks in 
cars so equipped.

Eric
Portland, Oregon
_________________________________________________________________
The mighty 71 four-door (440) refuses to bend to
repair attempts.  The shop and I have spent a lot of
time on this, but no soap.  The mechanic I'm using is
an older guy who is quite familiar with old
carburetted cars.  Though clearly not a brilliant
diagnostician, he's solved a number of other problems
on the car.
    The symptoms:  From a standing start or from
coasting at 0 to about 5 mph, flooring the accelerator
results in "backfire" popping out the top of the carb,
stalling or almost stalling.  A slower, more gradual
acceleration does not show this problem.  Also,  car
surges or bucks intermittently on hard acceleration
from a stop under a load, as in accelerating up a
normal freeway onramp leading to an elevated road.
  In the last month or so, new plugs, spark plug
wires and electronic distributor (mopar performance)
have all been fitted.  Scopes both in shop and onboard
show normal electrical performance.   Timing is
perhaps 5 or 8 degrees retarded.  Aside from this
problem, runs fine on 87 octane regular.  I also
frequently run 91 octane premium.
   Carb (Carter, not a thermoquad)  was just rebuilt,
with a new accelerator pump done twice, with no
improvement.  The shop found a service bulletin in an
old 69-72 Mitchells  book which described a similar
problem and gave a solution of re-boring some holes in
the carb and changing some of the metering needles.
Carb shop did this per the service bulletin, to no
effect.  Mufflers and resonators are new.
    Has anyone solved a problem like this?   Do I
have to buy a modern carb?



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