The #1,3 cylinders will be under pressure from the valve springs.
To keep it from lashing back I used a wrench on the crankshaft bolt
and zip-tied it to the water pipe. If you don't keep the crankshaft
in place the #1,3 cylinder will rotate since it's under load and
will turn the crankshaft, which will throw off the timing mark.
Don't ask how I know
. (Text by Windjammer)
Hope that helps!
With thanks to one of our most dedicated members of our
forum known as "Windjammer" who provided this clear picture for you.