Tune up proceedure for Gasoline Jeep engine, setting valve gaps and distributie positioning and testing.
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Film clip to show the proceedure for setting the ignition timing.
Notes The rotor arm on the top of the distributor should be at 1 0'clock position when piston 1 is on the compression stroke. For piston number 2 it would be at 10 0'clock , for piston 3 it would be at 4 0'clock and for piston 4 at 7 0'clock, so as the engine is turned over the rotor arm also moves. This relates to a 1,3,4,2 firing order. If the piston 1 is at 1 0'clock then the high tension cable to that position should be attached to piston 1. Proceedure for Ignition Tuning Turn engine over with spanner to TDC then to 8 degrees such that piston 1 is on the compression stroke. Remove the distributor lid/cables and unbolt the distributor and remove it. In the hole, using a screwdriver ensure the groove is set at 12 o'Clock position. Set rotor arm to 11 0'clock position and insert the distributor back lowering it into position, push down and insert bolt loosely in position. Rotor arm should now be in 1 0'Clock position. Spark test With the ignition switched on, disconnect the lead from the distributor cap and place near the engine and move the distributor until a spark is seen. Then tighten the bolt that holds the distributor in place to fix it in that position. Reattach the cables to the distributor/spark plugs and start engine. With a diesel engine rather than ignition timing we check injection timing The video and subtitle illustrate the process of setting the intake and exhaust valve gaps . A film clip of a gas jeep engine showing the proceedure for checking the engine tuning. Continutiy testing of the gnition switch to identify which terminal is which. ie: Start, Accessories, Ignition, Battery. The film clip shows the layout of pistons, valves, intake and exhaust manifolds etc (From July 31st session)
Running mate Piston (1 and 4) and (2 and 3) Running Mate Event (Intake and power) (compression and exhaust) Possible Firing order 1,3,4,2 (Isuzu, Toyota, Mitsubishi)) or 1,2,4,3 (Nissan) In graphing of individual piston strokes we need to know, the firing order, running mate piston, running mate event, the rotation of the engine, (clockwise or anticlockwise) , the sequence of series of events (ie c-p, e-i) and the crank angle of the engine. For 4 cylinder 180' 4 strokes = 720' or 2 complete revolutions. Intake Stroke
The Piston is going down so the volume of the cylinder is getting larger. The Intake valve is open. A vacuum, or pressure of less than atmospheric is created in the cylinder. Atmospheric pressure forces air into the cylinder. 14.7 psi at sea level. Fuel is mixed with the air, and the cylinder is filled with the mixture of air and fuel. Compression Stroke The Piston is going up so the volume of the cylinder is getting smaller.Both valves are closed. Air/fuel mixture is trapped in the cylinder. Pressure is increasing. Mixture is compressed into approximately 1/8 it's original volume. 150 psi built up. As the mixture is compressed, it heats up. Power Stroke The Piston is going down. Volume of the cylinder is increasing. Both valves closed. Spark plug fires, causing compressed air/fuel mixture to burn. The flame front travels across the combustion chamber. The burning fuel creates tremendous pressure which forces the piston down. turning the crankshaft and producing power. This is not an explosion, but a smooth, controlled burn. Exhaust Stroke The Piston is going up, so the volume of the cylinder is getting smaller. The Piston pushes the burned exhaust gasses out past the open exhaust valve, and out through the exhaust system and into the atmosphere. Both valves are open for a short period of time at TDC. This is called "Valve Overlap" The intake stroke of the new cycle follows this exhaust stroke. Engine terms Top Dead Center (TDC) - Point of uppermost travel of the piston and crankshaft. Bottom Dead Center (BDC) - Point of lowermost travel of the piston and crankshaft. Bore - Diameter of the cylinder. Stroke - Distance the piston travels on a stroke, or the distance from TDC to BDC. The stroke is twice the distance of the throw. Throw - The distance from the center of the main journal of the crankshaft to its rod journal. The throw is one half the distance of the stroke. |
Automotive Notes
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