High Idle
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=2169
Printed Date: November-23-2024 at 3:49am
Topic: High Idle
Posted By: Siveck
Subject: High Idle
Date Posted: July-29-2005 at 12:20pm
I finally have my boat to where it runs again after a long summer of working on it as usual. However, my idle speed will not go below 900 rpm or so. I've rebuilt the carb, made the adjustments, and have the timing set at about 12 btdc at 900 rpm. I figure that should be close at the spec is 10 btdc at 700 rpm. I hooked up a vacuum guage and I am getting 18 in Hg steady at this rpm. If I go any lower, then it surges and dies. I checked for vacuum leaks around the carb base and found none. It was running rich, but I found that the accelorator pump was slightly actuated at idle, so I adjusted that. I do have a mild cam in the boat, but 900 rpm still seems a bit high. And yes, people shake their fists in the no wake zone. I've had this boat for over a year and have never seen it idle below 900 rpm. Any ideas? Maybe the tach isn't accurate. The idle sounds fine, but the guage shows high. I am at a loss with this issue.
-------------
1975 Ski Nautique
"Small Letter Boat"
|
Replies:
Posted By: Jim_In_Houston
Date Posted: July-31-2005 at 1:14am
I know you checked for vacuum leaks but that is exactly what it sounds like. I found my vacuum leak by spraying WD40 around the carb base. The idle smoothed out instanty upon spraying and then wne back to high and rough. The carb gasket, a cheap Mr. Gasket, was leaking in a very small spot - about 1/2" long.
-------------
Happy owner of a '66 and a '68 Mustang
|
Posted By: 64 Skier
Date Posted: July-31-2005 at 5:47am
My boat is the same (cam w/incresed compression and no idea where the timing should be set)....after getting her running, we experimented with the timing (while running in the lake with and without a load) till it started smoothly and accelerated without knocking. Sorry, can't remember which way we went!
Let us know what happens and good luck.
-------------
64 Skier
66" HO VTX and 67" HO Triumph
http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC
|
Posted By: Guests
Date Posted: July-31-2005 at 5:21pm
|
Check for leaks around the intake and vacuum fittings as well as the carb.
|
Posted By: JEFF KOSTIS
Date Posted: August-01-2005 at 12:12am
Does it have a PCV valve? Defective?
-------------
MUSTANG COUNTRY
http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17
http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17
|
Posted By: Siveck
Date Posted: August-01-2005 at 2:56pm
I checked for vacuum leaks with carb cleaner on the intake around the carb and such and found none. I just changed the pcv valve and it is still the same. And still yet the same when I unhook the pcv valve and run it with the vacuum guage attached to the wedge plate port.
It runs very well, but the idle is a bit high. I guess that I will just live with it. It's not so bad that it would tear up the transmission, so I'll just let it be. Maybe my cam is supposed to make the motor behave that way. The power is definitely awsome. Thanks everyone for your input.
-------------
1975 Ski Nautique
"Small Letter Boat"
|
Posted By: stang72
Date Posted: August-03-2005 at 4:07pm
I was having high idle probs too...after going through a bunch of ajustments(carb,timing and ignition) I found a vacume leak...problem solved! I found the leak by blowing cigarett smoke arround the carb spacer...it sucked it right in at one spot.I now idle at 600 rpms and it is as smooth as a babies behind!
When mine was fast... I was told by the lake patrol to slow down...so I know what you mean!
If your idle is too fast...it will take a toll on the tranny...it should be smooth going into gear ...it would be best to find a fix!
-------------
stang
Face plants are not that funny when it's you face!
http://www.correctcraftfan.com/diaries/images/3720/photo1.jpg" rel="nofollow - The Super Air
|
Posted By: stang72
Date Posted: August-03-2005 at 4:11pm
Oh..forgot to metion...There was one other thing that we did that helped fix the prob....we retarded the timing a bit!The leak was the main offender though.
-------------
stang
Face plants are not that funny when it's you face!
http://www.correctcraftfan.com/diaries/images/3720/photo1.jpg" rel="nofollow - The Super Air
|
Posted By: Siveck
Date Posted: August-03-2005 at 5:35pm
It's actually smooth when it goes into gear. Maybe my tach isn't accurate. Oh well. It will be a mystery that I can live with.
-------------
1975 Ski Nautique
"Small Letter Boat"
|
Posted By: southwind 20
Date Posted: August-12-2005 at 2:33am
Just a thought, but setting the timing at 12 degrees instead of 10 will increase the idle speed at least on and automotive set up so you might try going back down to 10 and see what happens.
-------------
Git One ON!
|
Posted By: 79nautique
Date Posted: August-12-2005 at 11:26am
Running at 900 is about what mine likes to idle at. With the cam it needs a little more rpm at idle. A couple of suggestions for the no-wake zones, go a lot slower by going in and out of gear and I have also changed my prop to bring down the rpm's on top end bbut it also help the idle speed by having a slightly heavier load on the drive-line due to the increased pitch dropping the rpm down more.
-------------
http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
|
Posted By: Siveck
Date Posted: August-12-2005 at 12:30pm
Thanks for the tips everyone. I have been just going into and out of gear in no wake zones. I have my timing at 12 to 14 btdc because if I retard the timing to 10 btdc, then I have a misfire under acceleration. I'll just let it be at 900 rpm or so. Thanks everyone.
-------------
1975 Ski Nautique
"Small Letter Boat"
|
|