g6v30/45ATC 428 RMP S/NO 726239 1971

I could not locate a definitive reference or datasheet under the identifier G6V30/45ATC matching all the details you gave (428?RPM, serial no. 726239, year ~1971). However, I can share what can reasonably be inferred, what typical parameters such an engine might have, and what further information or steps could help you identify its full specification.

Here is a possible breakdown / conjecture and guidance:

What is known / what you provided

Designation: G6V30/45ATC

Speed: 428?RPM

Serial number: 726239

Year: 1971

Fueled by diesel

Likely an industrial or marine engine (given low RPM)

“428?RPM” is very slow for typical diesel engines used in vehicles or small machinery — it suggests this is a low-speed or medium?speed diesel, likely for marine propulsion or power generation, or possibly for large stationary duty (e.g. a generator or drive for heavy machinery).

The “G6V30/45ATC” nomenclature could encode parameters such as number of cylinders (G6 = 6 cylinders?), bore × stroke (30/45?), variant “ATC”, etc. But that is speculative without a manufacturer reference.