[Mgs] MGA sputtering engine

[The Roxter]

Robert J. Guinness wrote:
> As usual, I am mystified by my MGA.  On a recent trip, it began to 
> sputter and die.  I could start it again, and go a short distance by 
> pumping the gas pedal in unison with its dieing sputters.  Now the car 
> will only intermittently start.  If I rev the engine and hold the gas 
> pedal constant, the engine will run rough for a few seconds and then 
> the revs will drop steadily until it dies.
>
> I changed the spark plugs which were black and went to a hotter plug 
> (Autolite 63 gapped to .35).  I re-timed the engine (twice).  I had 
> replaced the points,and rotor about a month ago.  The car ran great 
> when I installed the new points so I know I installed them correctly.  
> The condenser is from last Spring.  I had reported to the list 
> recently that the cam block on the points on this car had worn  in 
> just a few months so that they hardly opened.  Barney Gaylor suggested 
> testing the coil to see if it was a ballister type, which it was not.  
> I replaced the ground wire on the distributor about a year and  a half 
> ago and inspection shows it is in good condition. 
> I had problems last year with a reconditioned head that the machine 
> shop had failed to lap the bronze guides.  The problem seemed to work 
> itself out.
>
> I am getting gas.  And my rudimentary spark plug tested from HF says 
> the plugs are sparking.  Compression shows all four cylinders within 5 
> lbs of each other (@125)
>
> This is a 1963 MGB 3-main engine with the original MGA carbs.
>
> For what its worth, the "rear seal" on the engine has began to leak 
> about 4 months ago.  I attributed this to a really nackered U-joint 
> messing up drive shaft.
>
> How should I go about diagnosing and repairing this problem.  Could it 
> be the condenser?  The camshaft?  Valves?  Bearings (rear seal leak)?  
> Vengeful gods? 
Some things to look for:

Failing coil

Failing flex ground wire in distributor (goes to plate)

Failing needle valve in float chamber(s) (too rich)

-The Roxter
--