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There have been several posts on SS discussing the slower operating speed of the M35A3 vs the M35A2, the limiting factor being the CAT 3116 engines. I personally limit my A3 to 45 mph for most driving and 2500 RPM. Others have admitted to running their CAT 3116 engines at significantly higher RPM. I now may have the final word. After a great deal of difficulty, I finally was able to talk to an engineer at Caterpillar concerning the 3116 engine. I found a lot of information on the CAT 3116 engine for marine applications and generator applications, but little for trucks and other applications. I discussed the CAT 3116 engine used in the A3 with an engineer at Caterpillar named Joe Gibbons, who it turns out was very knowledgeable about the engine and the ESP program the Army was running. I provided him with the S/N of my engine (5RMO3750) and he looked up the specifications for the engine in it's application. The engine is rated at 170 HP at 2700 RPM. This information was identical with what was on the data label affixed to my engine. I was told that although the engine would run at RPMs higher than 2700, that Caterpillar absolutely did not recommend anything higher, and that unpleasant things could happen at higher RPMs and that engine life would definitely be shortened. He also warned that the higher operating RPMs would result in a more frequent need for top-end service. The limiting factor with the CAT 3116 engine is apparently the valve train as opposed to piston speed. He recommended not running the engine continuously over 2650 RPM. He also told me that the same or similar 3116 engine used in heavy equipment was recommended to run at 2350 RPM for maximum engine life. Obviously, running an A3 and limiting the engine RPM to 2350 would slow the truck down to an unacceptable top speed. It's too bad AM General didn't use a transmission with an overdrive.
I have also heard people say that the CAT 3116 engine was not a very good engine. According to the CAT engineer, the CAT 3116 and 3126 engine series was very successful, especially in marine and generator applications with constant RPM requirements. I didn't realize it, but there are a significant number of variations of the CAT 3116 engine to the point where I would have guessed that most manufacturers would have given some of them separate model numbers.
I have also heard people say that the CAT 3116 engine was not a very good engine. According to the CAT engineer, the CAT 3116 and 3126 engine series was very successful, especially in marine and generator applications with constant RPM requirements. I didn't realize it, but there are a significant number of variations of the CAT 3116 engine to the point where I would have guessed that most manufacturers would have given some of them separate model numbers.
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We always called them a 6 pack motor. That motor was used in on a lot of stationary machinery too, like conveyors, crushers, pumps, and always running full bore. Also used in city buses.
It could be a chevy Big Block
