Brockport Bill 1,889 #1 Posted October 9, 2021 Made progress on solving surge for new to me P220 Onan on 520 HC ---- but now that its running i have different topic question????????? What are the correct rpms at idle and top end? Also, what should the vacuum guage read for the respective idle rpms and the top end full throttle RPMs? thanks all!!!!!!!!!!!!!!!!!!!!!!!!!!!! Share this post Link to post Share on other sites
Bill D 2,220 #2 Posted October 9, 2021 Did you download the Onan manual? All the information should be there. Share this post Link to post Share on other sites
Brockport Bill 1,889 #3 Posted October 9, 2021 i have an onan manual - all i see is max speed of 3600 ----- dont see that spec for idle rpm or vacuum Share this post Link to post Share on other sites
Bill D 2,220 #4 Posted October 9, 2021 42 minutes ago, Brockport Bill said: i have an onan manual - all i see is max speed of 3600 ----- dont see that spec for idle rpm or vacuum There may not be one. With full pressure lube you don't need a specific low RPM for proper lubrication. Not sure about the vacuum reading. Share this post Link to post Share on other sites
lynnmor 7,726 #5 Posted October 9, 2021 Governed idle speed is 1400 RPM, maximum speed is 3600 RPM. The vacuum gauge is simply a function of throttle opening and doesn't follow engine speed. As the throttle plate increases its opening, the vacuum drops. 1 Share this post Link to post Share on other sites
Handy Don 13,697 #7 Posted October 9, 2021 (edited) 6 hours ago, lynnmor said: Governed idle speed is 1400 RPM, maximum speed is 3600 RPM. The vacuum gauge is simply a function of throttle opening and doesn't follow engine speed. As the throttle plate increases its opening, the vacuum drops. @Brockport Bill The service manual is below is clear and distinguishes between the idle low limit and the governed idle (and how to set them). I was able to initially get the idle low limit down to less than 600 RPM (just to see how smooth it ran at that speed and to get the jet adjusted) but then dialed it back up per the spec. Edited October 9, 2021 by Handy Don 1 Share this post Link to post Share on other sites
Brockport Bill 1,889 #8 Posted October 9, 2021 you guys put encyclopedias to shame - you're the best !!! thanks 1 Share this post Link to post Share on other sites
