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running rich at idle 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=31870 Printed Date: October-08-2024 at 5:19pm Topic: running rich at idle Posted By: malibud Subject: running rich at idle Date Posted: October-23-2013 at 1:07pm Ok after it warms up 1985 2001 351W. it is very smokey in the back seat . like it is running rich . compression is about 140 across the board. carb has been rebuilt since then i changed the dist. a blew out the power valve (had dist backwards) . Changed the power valve to an 8 (i think) higher than stock (2) i think . Is this my problem ?. sitting in the back at idle with kids is not fun would a new carb help ? don't really want to throw 500$ at it . other than that boat runs great tops out about 45mph any ideas would be great thanks Dan Replies: Posted By: Nautiquehunter Date Posted: October-23-2013 at 1:58pm Is the carb mounted at an angle? If so the float level in the front bowl has to be lowered. Posted By: malibud Date Posted: October-23-2013 at 2:00pm no I do not think so it is stock . and i do not have any fuel dripping when running . but I could lower the front float if it would help. Posted By: phatsat67 Date Posted: October-23-2013 at 2:03pm Lots of variables. Is the timing right? Did you go by the idle mixture procedure? What is the idle rpm? The power valve everyone goes with (correct if wrong) I think is a 6.5? If the vacuum isn't right the valve could be opening but you will need a gauge to check that. The number means the vacuum level that the valve will open at. ------------- Posted By: malibud Date Posted: October-24-2013 at 11:56am went back and checked idle mixture screws turn all the way in and nothing happens all the way out and no change in vaccum . Ideas ? new metering block ? PV ? dont want to start throwing parts at it . float level is about level when turned upside down thanks Dan Posted By: phatsat67 Date Posted: October-24-2013 at 12:25pm Dan, have you checked timing? Sounds as if the thing is running on the transition circuits rather than the idle circuits. This happens if say the timing is too retarded at idle and you need to open the throttle plates so much that it starts to pull fuel from the transition circuit in the barrel. I highly doubt a vacuum leak because that tends to cause a high idle lean condition not too much fuel. When idle circuits are working properly and there is no vacuum leak present you should be able to kill the engine easily with one idle screw closed. Did you get a vacuum reading on the gauge? ------------- Posted By: malibud Date Posted: October-24-2013 at 12:47pm this on memory but timing is about 9-10 I advanced as much as possible before i got pinging on 87 gas. Vacuum is about 12. I wonder if my metering block might be bent? or power valve not right ? I can screw in the idle scres tight with no effects on the engine. I think this is causing the rich idle. Posted By: phatsat67 Date Posted: October-26-2013 at 11:35am Vacuum is wayyyyy to low. A healthy 351 at idle out of gear should be up near the 20in mark and at or above 16 or so. The normal problem with a vacuum leak is that it leans out the fuel mixture from the extra air in the system the carburetor doesn't know is there. Could be that the power valve is blown out leaking vacuum and fuel? That seems like the most logical idea at the time. Cheap and easy to replace. -------------

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