1978 VB Holden Commodore this morning, really sweet little car with a 5 litre V8 / TH400 combo. It's not running right so we might chase up some plug leads and plugs and give it a tune. Somebody replaced the original points ignition with a modern electronic one and didn't bother to hook up the vacuum advance so I assume the timing is out completely -
Be sure to hook that vacuum advance up to "ported" vacuum......very slightly above the throttle body. If you don't you'll have full vacuum advance at idle (much faster than it should be) and it'll never run like it should. At idle it should run at the initial idle advance setting before top dead center. Once the throttle is opened (takes very light throttle) you'll get both centrifugal (mechanical) and vacuum advance. At higher throttle settings and wide open throttle (lower vacuum), you'll just be running only on certrifugal advance.
Many folks used to just hook the vacuum advance up to any vacuum source and think it should work fine. Vacuum advance is there mainly for economy purposes. Running without it is not a problem but, if he's after performance, he should have the distributor set up on a distributor machine (by someone that knows what they're doing) so that the advance curve (how much and how fast [RPM] it advances) is optimal for the cam timing, the type fuel and other engine specifications. Probably not too many of them around these days though.
In the "old" days (60's through about early 80's), they used to sell generic pre-set advance "curve kits" that kind of worked, but usually not optimally. They usually just brought full advance on quicker (at a lower RPM) but, in many cases it would cause pre-ignition because of being too much, too soon.