This tutorial is also available in French
➔
Contact points tuning on Austin Mini
Vehicle ➔ Mini 1000 am1991 automatic gearbox
Difficulty ➔ Medium
Time ➔ 3 hours
Summary
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In the past, the distributor was commonly called delco (and the distributor cap Delco cap). Simply because Delco was one of the main manufacturers of distributors.
The contact breaker was also called contact points.
Adjusting the contact breaker requires turning the crankshaft with great precision. On a Mini with an automatic gearbox, the method of turning one of the front wheels does not work. The correct method is to remove the small rubber cap located above the torque converter bell to allow access to the starter ring gear. Then simply lever the ring gear teeth with a flathead screwdriver and turn the crankshaft. It's tedious but it works.
During the various manipulations, always turn the crankshaft in the direction of engine rotation. This allows to compensate for play.
To ensure good ignition of the air/fuel mixture, the spark plug must fire slightly before the piston reaches its top dead center. Thus, the air/fuel mixture can burn before the piston starts its descent. This is called ignition advance. On our 1991 Mini, the ignition advance must be set to 8°.
There is a second rubber cap (larger than the previous one) on the converter bell of Minis with automatic gearboxes. This cap allows access to the torque converter markings. These markings allow positioning piston #1 a few degrees before top dead center with great precision.
In this tutorial, we have detailed 2 methods for adjusting the ignition advance:
• The static adjustment (indicator light): method adapted to a first adjustment following, for example, the removal of the distributor or for people who do not have a stroboscopic lamp.
• The dynamic adjustment (stroboscopic lamp): the simplest and most precise method.
• The static adjustment (indicator light): method adapted to a first adjustment following, for example, the removal of the distributor or for people who do not have a stroboscopic lamp.
• The dynamic adjustment (stroboscopic lamp): the simplest and most precise method.
An indicator light is simply a 12V bulb mounted on a socket powered by 2 electrical wires. Crocodile clips attached to the end of these wires facilitate connection.
Required Tools
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Remove the distributor cap
Op 01
Remove the grille (➔ see the tutorial ''Removing the grille'' Op 01 to 04).
Op 02
Locate where the distributor is.
Op 03
Verify that the spark plug high voltage cables are well identified.
Otherwise, write the corresponding spark plug number on each of the 4 cables.
The spark plugs are generally numbered from 1 to 4 starting from the spark plug closest to the radiator (1st photo).
The identification of the high voltage cables will make things easier during reassembly.
Op 04
Remove the 4 spark plugs (➔ see the tutorial ''Changing the spark plugs'' Op 01 and 02).
Leave the high voltage cables connected to the distributor cap.
Op 05
Disconnect the high voltage cable at the coil. Pull by hand.
Op 06
Remove the 2 fixing clips of the distributor cap. Pull by hand or use a flathead screwdriver.
Op 07
Remove the distributor cap (with the 5 high voltage cables). Pull by hand.
Adjust the maximum opening of the contact breaker
Op 08
Locate where the small rubber cap of the torque converter bell is.
Op 09
Remove the small rubber cap from the torque converter bell. Use the small flathead screwdriver.
We see the teeth of the starter ring gear appearing. This is what will allow us to turn the crankshaft.
Op 10
Introduce the large flathead screwdriver into the hole of the converter bell.
Verify that the crankshaft turns when levering on the teeth of the starter ring gear.
Op 11
Remove the distributor rotor. Pull by hand.
Op 12
Locate where the contact breaker is.
Op 13
Turn the crankshaft to position the contact breaker open to the maximum. Use the flathead screwdriver.
We can see on the 2nd photo:
• The cam is positioned at its maximum extension (red arrow).
• The contact breaker is well separated (green arrow).
• The cam is positioned at its maximum extension (red arrow).
• The contact breaker is well separated (green arrow).
Op 14
Verify that the gap of the contact breaker is between 0.35 and 0.40 mm. Use the thickness gauges of 0.35 mm and 0.40 mm.
If the 0.35 gauge goes in and if the 0.40 gauge does not go in: the contact breaker is well adjusted
(➔ go to Op 18).
If the 0.35 gauge does not go in or if the 0.40 gauge goes in: it will be necessary to adjust the contact breaker. Go to the next Op.
Op 15
Loosen very slightly the fixing screw of the contact breaker support plate. Use the flathead screwdriver.
Op 16
Correct the angular position of the contact breaker support plate to obtain the correct screw gap (between 0.35 and 0.40 mm):
•
Either push with your fingers (1st photo).
•
Or lever with a screwdriver between the V-shape and the small protuberance (2nd photo).
•
To increase the contact breaker gap: rotate the plate clockwise (green arrow)
• To decrease the contact breaker gap: rotate the plate counterclockwise (red arrow).
• To decrease the contact breaker gap: rotate the plate counterclockwise (red arrow).
Op 17
Retighten the fixing screw of the contact breaker support plate. Use the flathead screwdriver.
Once the screw is tightened, do not hesitate to make a final check of the contact breaker gap. The plate may have moved slightly when tightening the screw. You never know.
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Adjust the ignition advance statically
Op 18
Disconnect the connector and the hose of the windscreen washer pump. Pull by hand.
Remove the windscreen washer bottle. Pull by hand upwards.
Removing the windscreen washer bottle will make it easier for us to access the converter bell.
Place a drain pan under the Mini vertically to the windscreen washer bottle because the liquid will flow when the hose is disconnected.
Op 19
Locate where the 2nd rubber cap of the torque converter bell is (the largest).
Op 20
Remove this 2nd rubber cap. Use the flathead screwdriver.
We can finally see the torque converter.
It is through this hole that we will look for the appearance of the torque converter markings.
Op 21
Turn the crankshaft to look for the torque converter markings. Use the flathead screwdriver.
On our Mini classics, the torque converter is frequently oxidized. Consequently, it is particularly difficult to see the markings. In addition, as the rotation of the crankshaft is really tedious, it is necessary to redouble your patience to successfully search for the markings.
The 0 mark appears when piston #1 is at its top dead center. I must admit that after several unsuccessful crankshaft turns, to facilitate my search, I watched for the arrival of piston #1 through the spark plug hole. The markings miraculously appeared at that moment.
I was so happy to find them that I immediately marked them with a marker (3rd photo).
Op 22
Turn the crankshaft to position the 8° mark in front of the torque converter bell mark. Use the flathead screwdriver.
These 8° correspond to the ignition advance that we must adjust.
Op 23
Turn on the ignition.
Do not start the starter.
Op 24
Loosen slightly the distributor fork bolt. Use the 7/16'' combination spanner.
Op 25
Connect the indicator light between the low voltage circuit and a ground.
Op 26
Rotate the distributor counterclockwise until the contact breaker is closed (green arrow).
Rotate the distributor slowly clockwise to the exact position where the indicator light comes on (red arrow).
The light comes on when the contact breaker opens.
Op 27
Tighten the distributor fork bolt. Use the 7/16'' combination spanner.
Op 28
As a safety measure, turn the crankshaft a full turn until the exact moment the indicator light comes back on.
Check that the torque converter is positioned again on the 8° mark.
If the converter is misaligned, restart the adjustment at Op 22.
Op 29
Turn off the ignition.
Reinstall the distributor cap
Op 30
Fit the distributor rotor on its axis.
To ensure the correct angular position, engage the boss of the rotor in the notch of the axis (1st photo).
Op 31
Fit the distributor cap.
To ensure the correct angular position, engage the notch of the cap on the boss of the distributor (2nd photo).
Op 32
Fit the 2 distributor cap fixing clips. Push by hand.
Op 33
Connect the high voltage cable to the coil. Push by hand.
Op 34
Reinstall the 4 spark plugs and connect their high voltage cables (➔ see the tutorial ''Changing the spark plugs'' Op 03 to 06).
It is at this moment that the identification of the high voltage cables proves very useful.
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Adjust the ignition advance dynamically
Op 35
Start the Mini and let it reach its operating temperature.
Turn off the engine.
Op 36
Disconnect the vacuum hose from the distributor. Pull by hand.
The vacuum hose must be disconnected so that the vacuum does not influence the distributor during the dynamic adjustment of the ignition advance.
Op 37
Plug the vacuum hose. Use a Ø4 mm screw.
It is preferable to plug the vacuum hose to avoid any air intake that could disrupt the carburation.
Op 38
Loosen slightly the distributor fork bolt. Use the 7/16'' combination spanner.
Op 39
Connect the power supply of the stroboscopic lamp (12V).
As the battery is in the boot, the power cables of the stroboscopic lamp are not long enough to connect to it. It is therefore necessary to find a + and a ground in the engine compartment.
Op 40
Fit the induction clamp on the wire of spark plug #1.
Respect the mounting direction of the induction clamp. The arrow engraved on the clamp must be oriented towards the spark plug (3rd photo).
Op 41
Start the engine.
Pull the choke a little to obtain a slightly accelerated engine speed (≈ 1000 rpm).
Let the engine run.
The slightly accelerated engine speed will generate a higher frequency of flashes from the stroboscopic lamp and the vision of the graduations will be clearer.
Op 42
Illuminate the torque converter with the stroboscopic lamp.
Verify that the 8° mark appears in front of the torque converter bell mark.
The stroboscopic lamp produces a flash synchronized with the spark plug spark. This stroboscopic flash gives the impression that the torque converter is stationary. We then see the graduation corresponding to the ignition advance appearing.
If the 8° mark appears: the ignition advance is well adjusted
(➔ go to Op 44).
If another graduation than 8° appears: it will be necessary to improve the adjustment of the ignition advance. Go to the next Op.
Op 43
Rotate the distributor very slightly to adjust the ignition advance to 8°.
Be careful, it's very sensitive!
•
To increase the ignition advance: rotate the distributor clockwise (red arrow)
• To decrease the ignition advance: rotate the distributor counterclockwise (green arrow).
• To decrease the ignition advance: rotate the distributor counterclockwise (green arrow).
Op 44
Turn off the ignition.
Op 45
Tighten the distributor fork bolt. Use the 7/16'' combination spanner.
Once the nut is tightened, do not hesitate to make a final check with the stroboscopic lamp. Two precautions are better than one.
Op 46
Remove the screw from the vacuum hose.
Connect the vacuum hose to the distributor. Push by hand.
Op 47
Replace the 2 rubber caps of the torque converter bell.
Op 48
Replace the windscreen washer bottle.
Connect the windscreen washer hose and connector.
Op 49
Reinstall the grille (➔ see the tutorial ''Removing the grille'' Op 05 to 06).
The End
