Help! High Throttle hesitation |
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KRoundy
Platinum Member Joined: August-23-2010 Location: Lake Stevens Status: Offline Points: 1702 |
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Best of luck! If I ever need to work on my carb I'll be pulling it and taking a trip down to your house. Let us know how it does. I'm guessing that black goo removal did the trick.
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Previous: 1993 Electric Blue/Charcoal Ski Nautique
Current: 2016 Ski Nautique 200 Open Bow |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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Not a lot I can tell you about that plate except that it's the stock plate for a fair number of marine 4160's and info on it is not very easy to find. I have one on a 4160 that feeds a 351 with gt-40 heads with no problem at all. Probably looked just like this |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Kevin,
It didn't take as long as i expected, I think I could do another one pretty quickly as well if you ever need it. Ken, your correct, mine looks just like that. Thanks for all of your guidance on this. hopefully the water test goes well tomorrow! |
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KRoundy
Platinum Member Joined: August-23-2010 Location: Lake Stevens Status: Offline Points: 1702 |
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Well? Any fun video to post?
Kevin |
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Previous: 1993 Electric Blue/Charcoal Ski Nautique
Current: 2016 Ski Nautique 200 Open Bow |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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nothing yet... Main breaker failure at the boat ramp kept me from testing the carb. I have a replacement intended to arrive this afternoon in the mail... Hoping to have it installed and up for a re-test on Saturday. |
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3735 |
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Kris, I am not a carb guy but your comment on Timing caught my attention.
You mentioned timing at idle. That is a good start but the important timing to measure is what you have at 2,500 rpm up to 4,000 rpm. Watch the timing mark move as you advance your rpm. It should advance smoothly as your rpm increases and max out around 35 degrees usually between 2,500 and 3,000 rpm. The max or total timing number is the one that will give you performance or melt your engine. If your distributor allows say 40 degrees at 3,000 rpm that is very dangerous for your pistons. The only solution would be to recurve your distributor or back off the idle timing setting till your max is proper. If your timing does not advance smoothly, if it jumps or does not move at all you need to go inside the distributor and repair it. If your distributor as it is set now at 11 degrees is only at say 30 degrees at 3,000 you are leaving power on the table. You can add idle timing to move your 3,000 rpm timing up or get the distributor re curved. Others that know the 351W better can give a better idea of the exact timing curve preferred but in general this is what you need to be aware of. There are two ways to verify this. Any speed shop sells timing tape that you put on your harmonic balancer or you can measure exactly how far it is from 0 - 10 on your boat and add a new line at 20,25,30,35, The easy way is to use a Set Back Timing light that allows you to dial in how much timing you want and use your normal timing marks. These are available for $80 or so and help. I hope it purrs next time out. |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Hi Mark, I have a set back timing light, and will check the total advance. The bottom of the distributor is marked 24° @ 3000 RPM, so I used that as my guide (new DUI distributor) to achieve an assumed total timing advance of 35° (11° initial). Without the engine running well in the water, I haven't been able to check timing under load, but I would like to do that as soon as I can. Thanks for the suggestion!
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3735 |
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Timing is rpm driven, it can be verified while running on the driveway in about 2 minutes. It sounds like you should be I I good shape but verify for peace of mind with your brand new engine.
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Could this be a fuel flow issue? Something like a plugged fiuel filter or anti-siphon valve?
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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So I am happy to report that it was a great trip to the lake this morning... I was able to take 45 minutes on the ramp since I had the whole place to my self. I checked ignition timing and found that it was accurate at 3000 RPM, ( 35°) and my 11° was good as an initial timing set point I think. I also was able to work through the throttle/trans lever adjustment that I have been unhappy with. Power was good with the replaced main breaker, so I launched the boat and spent about 2 hours of run time on the lake. The throttle hesitation is definitely gone, and I varied the RPM from 1500 to ~4000 without spending too much time at any one RPM. The carb rebuild was a good suggestion, and helped a lot Thanks to KENO and the others of you that chimed in.
I liked the way the motor started better before the carb rebuild, now it takes a couple of throttle pumps at the ramp to get it to start cold, but I also noticed that the choke opens very quickly, so I may need to read up on delaying the opening a bit. Over all, I am pretty happy. I still have a little bit of a drive line vibration, but I suspect that is a prop issue. I guess I will work through solving that as well, but it will likely take a back seat to the next few hours of boating time and getting the engine broken in. |
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Jonny Quest
Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2957 |
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Nicely done. Gotta love finding and fixing a problem.
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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KRoundy
Platinum Member Joined: August-23-2010 Location: Lake Stevens Status: Offline Points: 1702 |
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Well done, Kris!
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Previous: 1993 Electric Blue/Charcoal Ski Nautique
Current: 2016 Ski Nautique 200 Open Bow |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Thanks Kevin and JQ glad it is finally coming together! |
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