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The wise men tell us that the key to getting rid of linkage gremlins is to get the down links (the adjustable links that run vertically) dead-on vertical. That eliminates having to guesstimate and make a bunch of angles the same because, well, vertical is vertical, right?
The problem is that that's near impossible, so you make it as close to vertical as you can and then think clean thoughts.
The guy who set mine up is a pro and he pretty much nailed it. After six years, both sides are still about as close to each other as possible. When you hear an engine with both sides in synch, you never forget it. You can tell if a car driving past is in synch or not just from that sound.
For a long time, I thought I had synch or jetting issues or some dirt in the jets between idle and about 2500 rpm.
Miraculously, that all went away when I found a distributor without spark scatter.
Before you get mired in the whole jetting and linkage thing, I'd strongly recommend checking for spark scatter with a timing light by slowly working your way up the rev range from idle. It's easier and much less painful than what lies in wait for you down that other rabbit hole.
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