Flathead 1953 Buick. I don't think so. If it's a flathead then it is
not the original 1953 Buick engine. According to my 1956 Motors Manual
(19th edition) the 60 series was not introduced until 1954. The 1953
Buick engines consisted of 40, 50, and 70 series. All Buick engines
produced after 1950 had in-head valves and all of these had hydraulic
valves except for one model of the series 40 (straight 8). Look again.
Is it really a flathead? If so I bet it's a Ford V8 engine. The
ignition timing mark is located on the flywheel on all 1953 Buick
engines and the tooth with a "5" stamp (painted yellow) is the timing
mark.