two nights ago I was breaking in a rebuilt air cooled VW with an aftermarket cam that was very specific on the break-in procedure. it called for 1500-1800 rpm for 20-30 minutes with absolutly no revving above 2000 and no idling.
as soon as it fired up we realized we had no working tach.
thinking quickly I grabbed my digital timing light, hooked it up and we had a nice accurate rpm display to keep us within the cam manufactures guidlines.
If I hadn't done this we would have likely been in the neighborhood of 2300-2600 rpm trying to play it by ear, and might have damaged the new cam and lifters.
