1974 ski nautique 351 w pcm
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=39475
Printed Date: October-05-2024 at 6:29pm
Topic: 1974 ski nautique 351 w pcm
Posted By: Chris74
Subject: 1974 ski nautique 351 w pcm
Date Posted: July-25-2016 at 9:59pm
| I have had this boat for several years and have not been able to get set properly.new Mallory electronic distributer from ski dim put in.had Mallory 4160 carb rebuilt twice.new plugs,wires .have timing set to 5 degrees and still sluggish on hole shot or get a pop noise like to much fuel in carb .i turn in the air fuel screws to cut down on fuel and it only gets worst.I Tried using vacuum gauge in between pvc valve in valve cover and carb to set screws but no luck. Need advice |
Replies:
Posted By: TRBenj
Date Posted: July-25-2016 at 11:00pm
| Timing |
Posted By: Chris74
Date Posted: July-25-2016 at 11:44pm
| Sorry new to website and have 2 post on the go for same subject.didnt think first one went thru.have timing set to what mechanic told me and ski dim but reply on other post agrees its timing |
Posted By: Chris74
Date Posted: July-26-2016 at 12:05am
| Had a brain fart just realized you were the one that replied to other post |
Posted By: MrMcD
Date Posted: July-26-2016 at 12:57am
|
Map your timing curve. Start at idle and watch what it does and record the timing from idle to 4,000 RPM. Once you know what it does and when it does it you can fix it or rule it out as a possible cause. Timing is set on a mechanical advance and can be adjusted but you need to know what it does before changing it. Map idle, 1,000 RPM, 1,500 RPM, 2000 RPM, 2,500, every 500 RPM all the way to 4,000. It will stop advancing at some point between 3,000 and 4,000 n0rmally. You can do this with a set back timing light or buy a harmonic balancer tape at a speed shop or from Summit and it will allow you to read the timing all the way up beyond 40 degrees advance. Maybe your distributor has very stiff springs and it is not advancing as fast as you need or is coming in too fast. It should advance exactly the same each and every time you rev the engine and it should advance very smoothly with no stops and stutters. Takes time but the test is free. |
Posted By: TRBenj
Date Posted: July-26-2016 at 1:14am
| Testing is fine but 5deg initial is too low any way you cut it. 10-12 will almost assuredly fix the symptoms you describe. Keep it under 36 total. |
Posted By: Chris74
Date Posted: July-26-2016 at 8:29pm
| Thanks for the advise.should have joined this forum years ago.going to start with timing at 10 degrees and map it as you suggested. |
Posted By: Chris74
Date Posted: July-26-2016 at 10:33pm
| Ok.set timing to 10 degrees in drive way and with the idle screw backed out all the way I can only get it to idle down to between 700and 800 rpm |
Posted By: GottaSki
Date Posted: July-27-2016 at 10:58am
|
Something is amiss, take a close up photo of the carb on each side as it is now, maybe we can identify something. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Chris74
Date Posted: July-27-2016 at 8:51pm
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Posted By: Chris74
Date Posted: July-28-2016 at 3:36pm
    Hopefully you can see pictures of the carb. |
Posted By: backfoot100
Date Posted: July-28-2016 at 5:01pm
|
I'm getting a major headache standing on my head trying to decipher the pics but you have an automotive carb on that thing. It stands to reason that you can't get it to run right. Lack of "J" tubes might not be a complete giveaway as they might have been cut off. In Pete's lingo, a true hack job. OK, I'll give you that one. Then having externally adjustable floats could also be a retrofit that was added after the fact. For the sake of argument, I'll let you have that one also. To have both red flags on the same carb, not being able to make proper adjustments and still running terrible screams of the wrong carb. Put the proper marine carb on it and you'll be golden. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: backfoot100
Date Posted: July-28-2016 at 5:06pm
|
Then again, this might very well be one of those really funky marine carbs that KenO talked about someplace else. Get us a list number off the horn of it. That should tell us for sure. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: KENO
Date Posted: July-28-2016 at 5:11pm
Eddie It wasn't more than a week or so ago that this came up in one thread or another. Back when you used a big word like facetious  Back in 74 that is exactly what a Holley marine carb was like. No J tubes,(the tubes were cut at a slant) externally adjustable floats, and the 45 degree fuel inlet that Zach wanted to see on the QuickFuel carbs Also had the grooved, slabbed shafts that you can see from the bottom if you know where to look.. If he gets the list number off the choke horn, it'll most likely tell him it's a marine carb I'd say that's the original carb that came on the engine KenO Edit just saw your last post and we're thinking alike here, and it ain't FUNKY
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backfoot100 wrote:Posted By: backfoot100
Date Posted: July-28-2016 at 5:12pm
|
I stood up and the blood drained back from my head. Now it maybe looks like only the secondary bowl is adjustable and the primary has a plug in it. It all just looks weird to me. It's really clean though...LOL ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: KENO
Date Posted: July-28-2016 at 5:21pm
|
[QUOTE=backfoot100] I It's really clean though...LOL/QUOTE] Are you talkin' about your head, the carburetor or both? |
Posted By: Chris74
Date Posted: July-28-2016 at 8:09pm
| Sorry guys bear with me.Not much of a computer guy as you can tell by the way my pictures were posted.get that number off air horn and post |
Posted By: Chris74
Date Posted: July-28-2016 at 8:18pm
| The number is 3059 B . To bad clean doesn't make it run good.want to get it it in the water and see what the 10 degree timing is going to do.at the end of the day if I'm idling 150high and it runs good does it matter other than it bugging me because the idle screw is backed all the way out. |
Posted By: KENO
Date Posted: July-28-2016 at 8:43pm
 I think you may have looked in the wrong spot, the attached picture shows where to look. The number you found was probably on the side. |
Posted By: Chris74
Date Posted: July-28-2016 at 9:22pm
|
Ok thanks.ill check again |
Posted By: Chris74
Date Posted: July-28-2016 at 9:37pm
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Posted By: Skeeter
Date Posted: July-28-2016 at 9:59pm
| deleted |
Posted By: DrCC
Date Posted: July-28-2016 at 11:30pm
|
Exact same list as my 74 Carb looks way too clean. Did you paint the carb ??? And it looks to have been Frankenburetored at some point in it's life. |
Posted By: fanofccfan
Date Posted: July-29-2016 at 12:19am
| I noticed how clean that motor and carb look as well. Wish mine were half that clean! |
Posted By: Chris74
Date Posted: July-29-2016 at 10:25pm
| It just came from cr carb rebuilders.They have some process which he did not care to share which returns it to original colour.i think that actually sand blast it when it is all apart |