351 carb tuning

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   Well with the color of the smoke that's bad valve guide seals or rings. Basically it's burnt oil and no amount of carb tuning is going to fix it, but tune it up right first and it should help some. Just keep an eye on the oil level and limp it along until a rebuild is needed. Unless you have some extra cash laying around then you can have the heads ground and that should fix it as well.

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79nautique Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872	Post Options Post Reply Quote 79nautique Report Post Thanks(0) Quote Reply Topic: 351 carb tuning Posted: December-15-2007 at 11:53am
	Well with the color of the smoke that's bad valve guide seals or rings. Basically it's burnt oil and no amount of carb tuning is going to fix it, but tune it up right first and it should help some. Just keep an eye on the oil level and limp it along until a rebuild is needed. Unless you have some extra cash laying around then you can have the heads ground and that should fix it as well.

76'SN Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: August-20-2007 Location: United States Status: Offline Points: 60	Post Options Post Reply Quote 76'SN Report Post Thanks(0) Quote Reply Posted: December-15-2007 at 8:15am
	i knew it need a little attention as far as tune up is concerned since the person i bought it from a year or two ago ran it very seldom. they replaced the stock carb with what is on there now, which i looked up and found it was a 670 CFM. since they carb was diff i figured thats where i should start. i havent changed cap, rotor, wires, or checked initial timing. all i did was change plugs, oil and set idle because i was ready to ride when i got it and never have gotten around to anything else. and yes the smoke has a blue color to it. so im assuming start with the ignition overhaul and then the carb since im not really carb tuning inclined. thanks for the input
	hukt on fonix helpt me

79nautique Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872	Post Options Post Reply Quote 79nautique Report Post Thanks(0) Quote Reply Posted: December-15-2007 at 2:11am
	3/4 turn seems a little lean to me. But besides the carb if the plugs aren't gap right and in good shape, plus the timing and spark energy, aka bad coil then it all adds up so first a good tune up needs done then you can worry about the jets. So first things first, new plugs, cap, rotor, wires, proper idle mixture screw settings and idle rpm. once those are correct and you still have the shoot then we can look at the jets. But if the CFM of the carb is too much for the motor nothing will fix it but a new carb with a lower CFM rating.

boat dr Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: June-27-2004 Location: United States Status: Offline Points: 4245	Post Options Post Reply Quote boat dr Report Post Thanks(0) Quote Reply Posted: December-14-2007 at 11:17pm
	Chad , we dont care how you spell it is how well you listen....... If it is indeed the stock Holley it is a model 4160 with a cfm of 600. And yes the black soot on your transom could be related to the low speed or idle cicuit being to rich. A vacuum gauge gives the best results , highest reading in gear that will allow for instant starts without adding Any throttle will give you a cleaner transom. This is not hard to do but requires a little patience, 3/4 round out will give you a good starting point.........Boat dr
	boat dr 1949 Dart 1964 American Skier

nuttyskier2002 Members Profile Send Private Message Find Members Posts Add to Buddy List Gold Member Joined: September-28-2005 Location: United States Status: Offline Points: 669	Post Options Post Reply Quote nuttyskier2002 Report Post Thanks(0) Quote Reply Posted: December-14-2007 at 11:15pm
	76, how many hours are on the motor? The black deposits very well can be from burnt oil. Although the smoke coming from burnt oil (from the exhaust) is bluish white there will still be heavy black sooty buildup on the back.
	95 Malibu Echelon w/Mercruiser 350 Magnum Skier Former boats: 88 Ski Centurion Tru Trac II 59 Chris Craft Capri (woody)

76'SN Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: August-20-2007 Location: United States Status: Offline Points: 60	Post Options Post Reply Quote 76'SN Report Post Thanks(0) Quote Reply Posted: December-14-2007 at 10:56pm
	just wondering about carb adjustments for my nautique with a 351. it has a holley 670 with, what i am assuming, are stock jets. after about a day of riding, the back of the boat is covered in black exhaust deposits. and if i remember correctly on initial start-up and idling it seams so smoke somewhat. would this be carb related? i was told it could be burnt oil but just didnt sound right. i was thinking it was the carb becuase with WOT i stick around 38-40mph with a 13X13 prop. if so, should i reject or try to tweak what i have.
	hukt on fonix helpt me

351 carb tuning

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