Carb question, fuel mix adj
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=1985
Printed Date: May-13-2024 at 8:02pm
Topic: Carb question, fuel mix adj
Posted By: 88skisupreme
Subject: Carb question, fuel mix adj
Date Posted: July-01-2005 at 6:21pm
| I have a little black smoke, I think I need to adujst the fuel mix. The problem is that there is silicone all over the thing you turn to adjust it and I cant remember which way is leaner and richer. Its on a 351 |
Replies:
Posted By: skyhawkflyer
Date Posted: July-02-2005 at 3:13am
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Need more info. What kind of carb? Smoke only at idle? Silicone? Is this an automotive carb or did someone put the silicone rtv on it to stop the adjustment from slipping due to vibration? ------------- |
Posted By: 88skisupreme
Date Posted: July-05-2005 at 2:18pm
| its a holley 4 barrel, the silicone is only on the outside part where the wires attach. I'm pretty sure its the orignal carb |
Posted By: skyhawkflyer
Date Posted: July-05-2005 at 3:06pm
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OK, I'll assume this is at idle. Run your boat and get it to operating temperature, take it for a 15 minute ride not just idling around. Get it warmed up good.
Then at idle screw in one of your idle jets-either left or right, until your engine begins to falter. Slowly back out the jet until it runs as smooth as possible. Do the same on the other side with the adjustment. Go back and forth between the 2 jets until you have the optimum idle rpm, you can even use your tach if you want to. Some people leave it right there, at optimum idle, and that's fine. Try it and see how it works for you. C/C says after achieving optimum idle to open both jets 1/2 turn (richer) for the 4160 series carb. This supposedly helps with idle start up. Iv'e used both adjustments and they both work, although I prefer the C/C method. I do not get any black sooty exhaust residue on the back of my boat, so it's working for me! Hope this helps. ------------- |
Posted By: David F
Date Posted: July-05-2005 at 4:03pm
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88skisupreme:
The black disk with the wires is the choke which has nothing to do with idle mixture. The idle mixture screws are very small and are located in the side of metering block at the front of the carburetor. There is one on each side. Generally, 1-1/2 turns from seated is a good starting point. IMHO, both screws should be adjusted the same. So what you do on one side should be done on the other. Once you find a good running position, try it out. If you find the engine does not fire right up once warm, then turn the screws out about a 1/4 turn...this is what JT is referring to...a lean idle mixture will make warm starts harder. To answer your question, turn to the right to lean the mixture and seat the needle valve. Obviously, to the left makes the idle mixture richer. When seating the needles, do NOT tighten them as you will damage the needles. Also, if your engine runs rich above idle, you have other problems. |
Posted By: 79nautique
Date Posted: July-05-2005 at 4:03pm
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It sounds like you are looking at the choke stat. So if it only smokes when just started then you do need to adjust the choke and lean it out a little. Just mark a spot on the housing and choke stat that are in line, loosen the three screws around the outside and rotate the stat clock wise that should lean it out some. To double check if you are going in the right direction move it a bunch in one direction and the butterfly valve on the top of the carb will get really loose (lean) or it will get tighter (rich). Now you can go back to the marks and adjust slightly until it set where you want it. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: skyhawkflyer
Date Posted: July-05-2005 at 6:07pm
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We need to get carb manuals online so we can reference instructions... I try to keep it short but it seems the topics go on and on. Especially when it comes to principles, testing, adjustemnts, description. Adjusting the choke is a whole different subject! ------------- |
Posted By: 88skisupreme
Date Posted: July-05-2005 at 9:29pm
thanks for the info guys
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