Print Page - Proper idle speed RPM?

Title: Proper idle speed RPM?
Post by: Rich on July 20, 2018, 02:01:50 PM

The engine on my recently purchased 1988 ComPac 27 last idles at about 1,200 RPM. I'm new to navigating in and out of slips; with an engine idling forward at this RPM, I come into dock hotter than I'd like at times. This may be my inexperience, but friends who have sailed with me suggest lowering the idle RPM; one friend suggests 750.

Is there an accepted "standard" idle RPM and or is it a personal choice? What might be a suitable RPM in my situation, at least until I get more comfortable? Can I get a quick "how to" in adjusting the idle?

This is my third post in as many days, as I have many things to learn. So far have found no ComPac 27 owners in Annapolis area to befriend. Many thanks!
Rich

Title: Re: Proper idle speed RPM?
Post by: captronr on July 20, 2018, 03:27:11 PM

Welcome!

If you have a manual with your motor, it might say an idle speed and wide open speed.

Most outboards have a simple set screw that allows you to increase/decrease idle. What I think you want to avoid is setting the idle so low that the motor can DIE on you, when you most need it--getting into the slip. If an outboard, take the cover off, and watch the linkage as you open/close the throttle. Should be easy to see.

Ron

Title: Re: Proper idle speed RPM?
Post by: Rich on July 20, 2018, 03:51:29 PM

Thanks. I should have mentioned I have an inboard diesel Universal M12 engine. I think this comes standard in the ComPac 27-at least the older ones (mine is 1988).

Title: Re: Proper idle speed RPM?
Post by: jimhuber2 on July 21, 2018, 01:56:28 PM

Rich-
Between 1000 - 1200 is about right. Some have bumped it down to 900 or 950. If you come in to hot, try bumping the trans in and out of gear to slow you down. Once you see how quickly your boat slows on its own, you can play with it from there depending on the conditions. Enjoy that new boat!!

Jim

Title: Re: Proper idle speed RPM?
Post by: BobK on July 22, 2018, 10:18:00 PM

I checked my M12 today and it idles at 800 rpm.
BobK

Title: Re: Proper idle speed RPM?
Post by: Rich on July 23, 2018, 07:20:56 AM

Thanks to all for your replies. Very helpful!!

Title: Re: Proper idle speed RPM?
Post by: wes on July 23, 2018, 08:40:46 AM

I've searched both the Universal M-12 owner's manual and service manual and there is no factory spec for idle speed. They do say that max RPM is 3600, "cruising" RPM range is 2600-3300, and "fast idle" is 1500.

My engine idles just over 1000, probably close to 1100. At full throttle with my two bladed 12" prop, max RPM is right around 3200.

Here are links to the PDFs for owner's manual and service ("technical") manual:

https://www.westerbeke.com/operator's%20manual/200157_m12-m50_operator_man.pdf

https://www.westerbeke.com/technical%20manual/200155_rev2_m12-m35_technical_man.pdf

Title: Re: Proper idle speed RPM?
Post by: Rich on July 23, 2018, 09:12:19 AM

Wes, thanks for your post and especially for these manuals. I'm sure will be super helpful!!

Rich

Com-Pac Yacht Owners Association

Com-Pac Model Specific Discussions => CP-27's => Topic started by: Rich on July 20, 2018, 02:01:50 PM