I've set many engines with them running. Put clothes pin on rocker arms if oil splashes a lot. First time I was 9 years old and we had a 47 Willy's pickup with a 144 cu in Ford falcon engine with solid lifters. So old the fuel pump was also a vacuum pump that made the wipers work. Later we found a Thunderbird, 81 model that was rear ended with 17,000 miles. That truck was powerful then, with 5.13 differential gears. I bought a 12v wiper kit from good ole J C Whitney catalog, boys, we was cooking with grease then. Had a under dash heater. One of them rear seats out of a bronco fit just right. Had a big chunk of family land we could hunt on. I mean thousands of acres of woods. Roads and right of ways all over, three big ponds and a large creek to fish all summer. Creek was big enough for a boat. We had run of the place.
