replaced carb
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=4544
Printed Date: November-23-2024 at 6:08pm
Topic: replaced carb
Posted By: chughes
Subject: replaced carb
Date Posted: August-18-2006 at 12:00pm
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Just replaced carb (Holley 4 barrel) on 88 Martinique B/R. Install went easy enough but could never get the idle quite right,also when you put it in gear and give it a little juice it starts to stumble, but when you get it at 2500 rpm it sounds good. By no means am I a pro and am new to Nautiques boats. Also tested for vacuum leaks and found none. Any help would be appreciated.
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Replies:
Posted By: 79nautique
Date Posted: August-18-2006 at 12:26pm
well you need to adjust a few things you can't just bolt it on and it run right unless your extremely lucky which it sounds you wheren't.
You need to get a vaccum gauge to adjust the idle misture screw correctly to get you idle where it needs to be.
As far as the stumble that's the accelerator pump's adjustment not being quite right but you need to get teh idle mixture screw set right first before adjusting it.
First thing is to double check the cable adjustment and make sure that it is adjusted correctly. You should be able to remove the spring loaded connector attached to the throttle lever on the carb and they should line up exactly in the same spot adjust accordingly. Next move the morse control all the way down or full throttle, then check and makesure that the lower butterfly is vertical, use your finger to open the top butterfly to see the lower one. all of this is done with the engine off. Now once that's set right your ready to move on the the idle mixture screws and idle. Get a vaccum gauge and attach it to the PCV port on the spacer or the end of the hose, make sure you have a good seal with no leaks, then start adjusting the idle mixture screws on both sides of the carb they sould be move equal amounts side to side, so if you turn one in a 1/4 turn do that to the other one. Also adjust in small ingraments 1/4-1/2 turn at a time until you have the maximum reading on the gauge around 18 psi approximately. Now you can lower the idle and readjust the idle mixture screws again until it's optimized may take three or four shots at it.
Also before you do anything set the timing and make sure it's between 8-10 degrees BTDC beore messing with the carb adjustments.
Once you have all of that take it for a spin and see how it runs if you still have a stumble then you need to adjust the accel pump, there is a nut just forward of the throttle lever on the carb that is towards the base of the carb and dirrectly below the diaphram adjust that screw until the stumble is gone again small adjustments then try it out and adjust again as needed. That's a quick cliff notes version of it check out Holley's web site or the instructions that came with the carb for more detailed description and pictures to locate the items to adjust.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: 79nautique
Date Posted: August-18-2006 at 12:33pm
where are you located?
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: chughes
Date Posted: August-18-2006 at 12:38pm
Posted By: chughes
Date Posted: August-18-2006 at 12:40pm
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This boat may need more work than I am aware of, it has only been in the water 7 of the last 12 years. It had been out for 4 until this summer when we put it in.
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Posted By: 79nautique
Date Posted: August-18-2006 at 12:47pm
well change the plugs, cap, rotor, spark plug wires and set the timing then we can get that carb dialed in and you'll be in good shape.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: chughes
Date Posted: August-18-2006 at 12:52pm
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any online recommendations for procuring these items or are they just standard 351 app. parts.
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Posted By: chughes
Date Posted: August-18-2006 at 12:53pm
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Thanks for the assistance. Mas appreciated!
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Posted By: 79nautique
Date Posted: August-18-2006 at 1:08pm
the plugs should be autolite 24's the cap and rotor you should be able to get at NAPA or the autoparts store just get the model number off the distributor. The plug wires need to be marine their a little longer than automotive wires to get around the risers. You can get all of that from www.SKIDIM.com just be sure and tell them you a CCF (correcrt craft fan) member to get a 10% discount.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: chughes
Date Posted: August-18-2006 at 1:15pm
Posted By: bmiller
Date Posted: August-18-2006 at 2:44pm
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hey 79 when you adjust that accelerator pump nut is that like 1/4 turn increments or what?I have that slight stumble with the brand new 450cfm I just installed.It only happens when I give it alot of gas to get a skier up.Other than that the carb is set up pretty well.
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Posted By: GottaSki
Date Posted: August-18-2006 at 3:40pm
bmiller
Set the clearance .040 at wot. This way it doesn't bind at wot, thats the only adjustment
The linkage should then have no slop at idle, so it squirts asap.
Set your air screws in gear, not neutral.
If it still stumbles off idle, bump up the timing. 10 btdc works best for most.
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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Posted By: bmiller
Date Posted: August-18-2006 at 3:46pm
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I'll give it a try,thanks for the tip.
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