MG Car Repair: valve adjustment, mg engines, compression stroke

Question
I just learned about the procedure of, subtracting the valve number that is  fully depressed from the number 9,and then adjusting that value number. I have adjusted values by removing the distributor cap and rotating the engine until the points open. The intake and exhaust valves of that cylinder are then adjusted and the engine then rotated to the next point opining. This procedure is much easier for me,with no watching for valve movement and subtraction involved. Are both procedures as accurate?

Answer
Hi Albert,
Either system works on a 4 cylinder inline MG engine, So you can use what ever method you like of the two. There are other methods too. In the dealerships we used a method called the mirror method. If you just imagine a mirror in the middle of the head and rotate the crank until a valve it opened as seen by the spring being compressed. (It so happens that two are compressed at the same time)then adjust the opposite valve that is compressed. So two can be adjusted at the same time. We usually pulled all the plugs and put the car in 4th gear with the hand brake off. This allowed us to easily push the car with our leg against the front bumper and thus rotate the crankshaft. When #1 and #3 springs are compressed we could set the valves of #6 and #8 then just lean against the bumper and #5 and #2 are compressed at the same time so we set #4 and #7 etc. This method we set two valves at a time and only have to roll the car a very short amount to have all the valves adjusted in the shortest time. This works on 6 cylinder engines too.
Most street engines have a round base on their cam so any of these methods work ok. Some mechanics use a version like your points opening. They just watch the valves on #4 cylinder go into "overlap" which means both valves are slightly open the same amount. This means that #1 cylinder is at TDC of the compression stroke. (points just opened too)and they can set the intake and the exhaust valves of #1 cylinder. All 4 cylinder MG engines have #1 and #4 pistons at TDC at the same time except that one will be on the top of the compression stroke and the other cylinder will be at the top of the exhaust stroke. #2 and #3 are up at the same time too.
Howard