On 29 Dec 2005 Patrick Mulholland wrote:
>"When engine is idling (1,000 RPM) and I depress the clutch, engine starts to labor and the revs dramatically reduce (even if neutral gear is selected) and eventually engine will stall unless I give it more fuel or release the clutch."

Pressing the clutch pedal applies end load on the crankshaft. This load is taken between the release bearing and the center thrust washers on the crankshaft, both of which exhibit a small amount of friction. A small slow down in engine speed is normal.

When stronger clutch springs were used for the MGA MK-II (and superceded for all replacement parts), tune-up instructions in the workshop manual were changed to include having a helper hold the clutch pedal depressed while setting the idle speed.

If the engine is in good tune, a small load at idle speed will slow the idle slightly and increase torque to compensate for the load. If the engine is slightly our of tune, especially if running a little lean, a slight slow down in idle speed will reduce torque, and the engine will die.

The cure is a tune up to get the fuel mixture and ignition timing right. If the problem persists, do a compression check. An engine with very low compression can be quite sensitive to small loads at idle speed. Also set the idle speed with clutch depressed. Then releasing the clutch pedal causes a slight increase in idle speed.