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MG MGA - Motor stumbles

60 MGA -
Drove the A over 200 miles last month and she ran perfecly. Restarted yesterday at first pull, idle is perfect but when I roll on the throttle the motor stumbles and backfires.

- needles not sticking
- oil in the dash pots
- checked for contamination in the fuel bowls
- carbs are matched and sound the same
- cap and rotor look perfect
- checked plugs and wires
- distributor is tight so it hasn't moved
- tightened carb to manifold

Have yet to put a timing light on it. Next on my list.

Any other thoughts?

Thanks all - Skip in CA
k brown

Skip

You say the carbs are matched. Is this a check you have done since your trip? I had not dissimilar symptons recently and I discovered that one of the throttle rod couplings had come loose, so only one carb was working above idle.

Steve
Steve Gyles

If one of the flex clamps on the throttle shaft between the carburetors comes loose, the throttlw cable works on the rear carb only. If you were tuning it recently you may have left a throttle shaft clamp a little loose. Go pull the throttle cable and see if the front carb opens along with the rear one. It's a little embarasing, but an esy fix.

The car will start and idle fine, and pulls reasonably well at low engine speed, just a little low on torque. But when you get on the throttle to make some revs it looses a lot of torque above 2500-3000 rpm. At higher speed it feels and sounds like running on two sylinders, as the rear two get a full gulp but the front tws starve with a closed throttle. The only air getting to the front two is what sneaks through the balance pipe on the manifold, and then you're running four cylinders on one carburetor.
Barney Gaylord

Did you replace the fuel filter?
Tom

I was having a similar problem a few months back and thought I tried everything. Carbs adjusted, mounted, checked for leaks, etc. It only gave me a problem when I tried to drive it under load. I took the carbs apart and noticed that one of the cork jet gaskets was dry and split. They were not that old and the car was run regularly. Maybe just a fluke. A new set of oil-soaked gaskets and it was like a new car.

I hate to admit it, but I have left one of the flex clamps loose before an an old MGB about 15 years ago. That's one of the first things I check now!
Tommy

This thread was discussed between 24/06/2006 and 26/06/2006

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