71 and older cars have factory vented caps. They are supposed to leak, so testing them is moot.
And I think he said 95 and newer cars all have a sensor to moniter tank vacuum, so if the cap were leaking it would trigger a fault code. Besides they always take the cap off while the engine is running to test it. On the newer cars this is a no-no since it can interfere with the FI and cause the fault code.
Kev, dist is a German 009 with Pertronix & German blue coil. I think its set to about 30 deg total.
I've had battery problems lately. The tiny dry sump pulley does not charge very well since the alternator/cooling fan are going about half their normal speed. I noticed with the cold it was very hard for the starter to crank it over, just like if you had a hi CR engine with lots of advance, so I knocked the timing back to about 30 total. This helped a lot. Then to also help the charging, I raised the idle speed to about 1050. With the tiny pulley and the rear tin removed, I can just barely get it up to 170-180 if I go out on the fwy. But at aircare, the temp started to climb idling that long of time. When I drove it up on the rollers it was at 195, and at the end of the test it was at 220! And that was at a time when it was almost snowing outside!