Engine, RPMs, and Prop

[Randy]

My newly purchased 84 C-27 with the Universal M-18 (14hp)diesel will cruise easily at 2000rpm. But, when the throttle is pushed all the way forward, the engine revs increase to about 2300rpm, but no more. Shouldn't this engine be capable of 2500-2800rpm, assuming the prop is correct?I believe that the prop is correctly sized based on the recommendation of Catalina/Universal, though now that the boat is in the water, I can't check the prop. For what it's worth, when pushing the throttle forward, it felt as though the engine was held back by lack of throttle travel, as opposed to the prop. i.e. it pulled strongly right up to 2300rpm. Also, there is minimal soot on the transom, so I'm not thinking the engine is grossly overloaded by the wrong prop.Any ideas or suggestions?

 

[Gary Jensen]

more throttle

Check your throttle first. Make sure that it is securely fixed in place and that it does not slip. If its ok, then disconnect it and see if there is more travel to be had (by hand). If there is, lubricate everything except where its fastened and re-attach it. Good luck

 

[Randy]

Throttle Stop

Upon further investigation, it appears my rpms are limited by the throttle stop on the engine. In neutral, the engine will rev strongly to 2500 rpms, but no higher. The throttle mechanism is limiting engine speed--it hits the adjustable stop mechanism. My first reaction was to simply adjust it, but in addition to the lock nut, it's wired (with rigging wire?), and appears to have not been touched since installation. Is there a reason the factory (or a mechanic) would limit the rpms to 2500? Do other Universal M-18s rev higher, or are they limited for some reason?Randy