Mid RPM Miss need Help
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=6922
Printed Date: November-15-2024 at 6:39pm
Topic: Mid RPM Miss need Help
Posted By: 2_Nautiques
Subject: Mid RPM Miss need Help
Date Posted: June-02-2007 at 3:37pm
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I am having problems with my 1978 Cuddy with an OMC 350. It runs great except from about 3000 to 3400 RPM then it has a slight miss. When I open it up it goes away or if I keep it below 3000 it is gone.
It runs about 4200 WOT at 36 MPH. I use the boat on Lake Erie and very rarely run over 2800 RPM. I noticed the miss towards the end of last season. This season I made the following changes: - Removed gas tank and cleaned it out, lots of gunk from years of neglect - Installed new fuel lines from tank to fuel pump - Installed new fuel filter - Installed new Pertronics Electronic ignition - Installed new coil The cap, rotor and wires where new when I bought the boat 2 years ago. When I installed the electronic ignition, I started the motor up in the driveway and set the timing to 10 deg. I had to move the distributor quit a bit as it was too far advanced. When I moved the distributor back to 10 deg. I had to adjust the idle screw up slightly. What should I be looking at next? ------------- http://correctcraftfan.com/diaries/details.asp?ID=1160" rel="nofollow - 1988 Ski Nautique |
Replies:
Posted By: wannabeSS
Date Posted: June-02-2007 at 4:05pm
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cap/rotor/wires would be my guess ------------- 96 Camaro SS #1157 84 Ski Nautique, fat sacks, fly high pole 06 LF Fish 125 06 LF PS3 137 |
Posted By: 79nautique
Date Posted: June-03-2007 at 7:28am
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since you had a lot of gunk in the tank check the vent/check ball at the tank and make sure it's clean as well. Also check and make sure a wire isn't loose at the cap or at one of the plugs. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 2_Nautiques
Date Posted: June-03-2007 at 10:50am
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79, I tore down and cleaned all the gas tank fittings including the ckeck/antisiphon. The wires seem tight on the cap and on the plugs.
can't understand why it runs so good except in the mid RPM. It doesn't sound like a fuel problem, seems more of a miss. Inspected cap and rotor, they look like new? ------------- http://correctcraftfan.com/diaries/details.asp?ID=1160" rel="nofollow - 1988 Ski Nautique |
Posted By: 2_Nautiques
Date Posted: June-05-2007 at 8:10am
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Why did I have to increase my idle stop after adjusting the timing after I installed the electronic ignition module? I would have thought that it would be the same with points or electronic? It is a chevy 350, I set the timing to 10 deg. is this correct or should I be more advanced? ------------- http://correctcraftfan.com/diaries/details.asp?ID=1160" rel="nofollow - 1988 Ski Nautique |
Posted By: 2_Nautiques
Date Posted: June-06-2007 at 10:52am
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With no responses, guess I will try new cap and rotor, where is the best place to get a Mallory flat cap and rotor? ------------- http://correctcraftfan.com/diaries/details.asp?ID=1160" rel="nofollow - 1988 Ski Nautique |
Posted By: nuttyskier2002
Date Posted: June-06-2007 at 2:07pm
I would think that the reason you had to increase idle after installing the Pertronix is that your timing was advanced a little too far when you had your points in. Advancing timing at idle (to a certain point) will increase idle speed. 10 degrees at idle sounds pretty close for your engine. It's best though to check timing advance at 3000 RPM with a variable strobe light. The SBC likes about 34-36 at 3000 RPM. ------------- 95 Malibu Echelon w/Mercruiser 350 Magnum Skier Former boats: 88 Ski Centurion Tru Trac II 59 Chris Craft Capri (woody) |
2_Nautiques wrote: