Frickin' timing chain

While dwb is right,
I have a simpler way,I think;
It only works well on engines without tensioners.
I just rock the balancer back and forth; you can easily feel when the cam starts compressing a spring. Find the points,stop at the slightest resistance,estimate the degrees of rotation.
If you like you can rotate the balancer so that the TDC mark is at TDC (either piston) , and then rock-it. Now you can read the actual degrees.
But how do you know how much is too much? Well that kindof depends what the combo is and what it is being used for. A DD teener seems to run fine right up until the day the chain jumps, so I guess 8 degrees might be a limit for it.(I have seen them come in,running, with a lot more than that). A finely-tuned drag-racer might want to pull it, at 2 to 4 degrees. A 360 streetrod is probably good to about 4 to 6 degrees; and a streetrod 318 might want to swap it out a little sooner, to maintain the tune.
Timing chain stretch, retards the cam-timing, and along with it, the ignition timing. The ignition timing is easy to get back.
Four degrees of cam timing cannot usually be felt on the street. I even had trouble saying there was any change at all in advancing my 292/508 at anything but the high revs. My G-Tec Pro measured it;so a dyno would see it.
But 8 degrees will most definitely show up in your DD-teener as a fuel-mileage loss. But again, your DD-teener has a goodly amount of torque below 2400 rpm, so a small loss due to the retarded cam just means driving a little deeper into the carb.
A DD slanty tho, does not have that torque advantage, so Ima thinkin it might be quite sensitive.I remember when, after an engine rebuild, my slanty turned into a dog. I had had the engine-shop install a tiny bit bigger cam, and had bumped the compression to 9.5ish. After trying everything I could think of, I checked the cam-timing, which was spot on. But my new engine was soggier than the low-Compression,oil-burning pig, I had just pulled outta that beast. So I advanced that cam just 4 degrees and the difference was immediately apparent. But with a starter gear of 2.74Low x 2.73=7.48 the new cam was a mistake.Or the 2.73s were :( In any case, the new greater MPGs were worth it. And really that was my goal with this combo. I just thought I could get away with a wee bit more cam.In the end it took a 2800TC to wake it up the low-rpm range, to even just equal the engine I took out.After about 3000 the new cam did wake up some,and revving it up to 4500, was a different story; the little slanty was a bit livelier up there.

Long story short, install the cam where the manufacturer says to,and make sure it stays there a good long time, by using a quality chain SET.