#1 and #4 travel up and down in the block as a pair. #2 and #3 do the same, just exactly 180* opposite of 1 and 4.
While #1 is coming up and compressing (both valves closed), #4 is exhausting (coming up with exhaust valve open, intake closed). At the same time, #3 is on its way down on it's intake stroke (intake valve open, exhaust valve closed) and #2 is on its way down actually firing after the spark (again, both valves closed).
The first gear, the drive gear on the crankshaft, has 33 teeth to it. It's half the diameter of the cam gear which has 66 teeth. Result is that the crank comes around twice for every time the cam turns. That may sound odd or mysterious, but makes sense if you remember that at TDC you will alway have two pistons up and two pistons down at their extremes, but doing different things at that very moment as described. The trick, problem . . . is, or may be, that if you had #1 at TDC on the wrong stroke when you matched up the marks between the crank and cam gears, everything on the front of the motor will look right, but you'll have the wrong valves doing the right thing at the wrong time, if that makes sense.
The good part is that if you lined up the single punch marks between the crank and cam gears correctly, the worst scenario is that you will have the cam 180* out of where it originally was, and you can fix it with the ignition timing without tearing the front back off the motor. TDC on #1 is also TDC on #4. You just need to match the spark up to the point that it will do you some good.
That will mean turning your distributor/mag/governor gear until the rotor is at #1 at the top of the #1 compression stroke.
It's good that you're using a hand crank. Much easier to check things out with than a starter motor.
It can be a bear to find, but find the TDC mark on your flywheel (Use brake cleaner and scrapers, whatever you have to to find it). That's the only place on the motor that TDC is marked. Problem is it's not marked particularly well. You can see the mark looking up through the oval shaped hole on the bottom of the torque tube, but the stamping on the flywheel is so shallow that it's often obscured and may take some scraping to find. You can get near to TDC by looking in the plug hole or putting a stiff wire or screwdriver on top of the piston through the plug hole and watching its motion, but the mark is much more reliable. (On the other point, of engine orientation, the mark on the flywheel, when you find it, will be marked TC 1-4, referring to both of those cylinders being at TDC.)
To get to TDC and know which stroke you're on on #1 . . . pull all your plugs out so the engine will turn easily. While someone turns the crank for you, stuff whichever finger fits into the plug hole on #1. On the firing stroke, the piston will be moving down with the valves closed and you should feel a strong vacuum. On exhaust that follows you shouldn't sense much pressure either way. On intake, the next stroke, again not much pressure, though you might feel a little pop in between the two strokes. On compression, you will feel enough pressure to blow your fingertip out of the hole. The end of that stroke is where you want to set things up.
Note the angle of your hand crank when you hit TDC on compression (accuracy is not critical at this point), then go back to what I described in my last post. With the valve cover off, have your helper turn the crank one-and-a-half turns (accuracy is not too critical here -- if you're that far out it will be evident) while you watch the front two valves and the back two. From that point to continuing on to two full turns, you should see both front valves closed (at top) and not moving. Of the back two, the one at the rear, the exhaust valve for #4, should be down (open) at 1-1/2 turns and rise to the top (closed) just as you get to two full turns. At that point, your cam is timed up fine.
Get your motor to that point, line up the mark on your flywheel to be exactly at TDC (If your helper should crank to where it goes past the mark on the flywheel, you can either back up using the fan to turn the other direction, or go TWO turns around and come up on it more slowly to get it on the mark.) and then set your mag up to fire on #1. If everything else is in order, that's the spot where she'll run.
There are those that would argue for just swapping wires to get your firing order in the mag back in order, but the gear ratios defy 4:1 (66 doesn't divide evenly by four), and will leave your starting spark as much as 5* out of time, which could be overcome by the crankig spees of a starter motor, but can make the differnce between starting and not with a crank..
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Today's Featured Article - A Lifetime of David Brown - by Samuel Kennedy. I was born in 1950 and reared on my family’s 100 acre farm. It was a fairly typical Northern Ireland farm where the main enterprise was dairying but some pigs, poultry and sheep were also kept. Potatoes were grown for sale and oats were grown to be used for cattle and horse feeding. Up to about 1958 the dairy cows were fed hay with some turnips and after that grass silage was the main winter feed. That same year was the last in which flax was grown on the farm. Flax provided the fibre which w
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