Ignition - MG MGB TOURER GHN5 Handbook

IGNITION
Ignition t i m i n g
D i s t r i b u t o r
Fig. 7
The ignition timing is set dynamically to give optimum engine performance with
efficient engine emission control. Electronic test equipment must be used to check
the ignition timing setting and the automatic advance (see 'GENERAL DATA').
Checking and adjustment to the ignition timing setting should be carried out by
a Distributor or Dealer.
The dynamic ignition timing must be checked after cleaning, re-setting, o r
renewing of the distributor contacts.
Cleaning contacts. Inspect the contact points (1) and, if burned, clean with fine
emery cloth o r fine carborundum stone. Wipe the contacts clean with a fuel-
moistened cloth. Renew pitted or worn points.
Lubrication. Very lightly smear the pivot post (2) and around the cam (3) with
grease. Add a few drops of oil through the hole (4) in the contact breaker plate to
lubricate the centrifugal weights and around the screw
(5)
in the centre of the
cam spindle (do not remove this screw as clearance is provided for oil to pass).
Avoid over-lubricating. Carefully wipe away all surplus lubricant and see that the
contact breaker points are perfectly clean and dry.
Contact breaker gap. Turn the crankshaft until the points are fully open. Check
the contact gap (1) with a feeler gauge (see 'GENERAL DATA'); the gauge
should be a sliding fit in the gap.
If the gap varies appreciably from the gauge thickness, slacken the contact plate
securing screw (6) and adjust the gap by inserting a screwdriver in the notched
hole (7) at the end of the plate and turning clockwise t o decrease and anti-
clockwise t o increase the gap. Tighten the securing screw. Turn the crankshaft
and recheck the gap. Refit the rotor, wipe the inside of the distributor cover
clean and refit.
Contact set renewing. Removing. Remove the nut (g), lift the top insulating bush
and both leads from the stud. Remove the securing screw (6) with its spring and
plain washers, and lift off the one-piece contact set. If removal of the moving
contact only is required, leave the securing screw (6) in position.