How do I do that w/o any timing marks? I tried using the screwdriver method but it gets jammed,
Be careful...... you can cause damage doing that.
Do the 3 holes in harmonic balancer mean anything?
Not for your purpose.
I also don’t see a rear timing cover but just took a cursory look.
I want to do a leak down test on each engine as a baseline.
Since this is all you are wanting to do, there is no real need for an accurate #1 TDC Compression Stroke location.
However, if you want to know where #1 TDC C/S is located, you will need a PPS tool.
At near TDC (as close as you can estimate) make a mark on the balancer and a corresponding reference mark elsewhere.
While NOT near TDC, the PPS tool will be threaded into the #1 spark plug port.
Bring the crankshaft around around until the #1 piston gently touches the PPS. Be gentle!
Make a new mark on the balancer.
Now rotate crankshaft in the opposite direction until the #1 piston once again gently touches the PPS.
Make a another mark on the balancer.
Shoot for a 30* +/- spread.
If not near 30* +/-, increase the depth of the threaded PPS stop portion, and repeat the process.
With these two new harmonic balancer markings equally divided, you will have a center mark.
Now remove the PPS tool.
Rotate crankshaft until the "center" mark aligns with your corresponding mark, and you will be a TDC (not necessarily on the C/S).
In order to perform your cylinder leak-down test, you will begin with #1 at TDC on the C/S.
Perform your leak-down test.
You will now rotate the crankshaft 90* of which will place the #8 cylinder at TDC C/S.
Perform your leak-down test.
Continue this 90* rotation stopping at each cylinder that is next in the firing order.
thanks
Bob