I have been adjusting the idle mixture screw on my one barrel holley on my 66 200 I6. I had a friend who is a retired mechanic adjust the idle and the mixture screw on the carb. before it did not smoke at all. Now at start up and periodically it smokes. Also when I start the car it spits a little black carbon? out of the tail pipe. Do you think its set too rich? It runs better the way it is set now. Just a little concerned about the smoke. When the car is driven a while and you turn it off for 10 minutes or so and start it back up there is a smoke cloud that comes out of the tailpipe and clears as soon as you drive. I have the timing set correctly , what is the best way to set the carb? My mechanic buddy told me to set it to get the fastest idle while adjusting the mixturs screw then adjust the likage idle to the correct RPM.
Carb idle mixture setting
- Thread starter franko66
- Start date
For the basics of fuel and idle...that is correct.franko66":3jb24e4e said:
I'm gonna say...wait and see....don't you love that kind of answer.
This sounds exactly like what mine did after Pony repaired my new vaporizer 1100. It was running rich, gushing fuel down into the cylinders...after they fixed a problem with the float, I had some initial smoking a couple times, and like yours, I had a carbon stain in the driveway. I think it had been so rich the carbon that naturally built up in the cylinders over time was broken free by the gas soaking. Within a few days it stopped smoking at start up and stopped shedding carbon.
You could be running rich, but I'd suggest giving a few days (starts&drives), and see if it continues to smoke or shed. If it goes away I'd run a fuel system cleaner (like Berrymans) in the tank. Of course you, could always lean out the mixture a little more until it starts to stumble then increase it slightly...but that sounds like what your buddy did.
If you want a more drastic method for decarbonizing the cylinders you can use water and a spray bottle and spray some mists down the carb throat while the car is running at a higer sustained idle, or do the same with a few ounces of ATF (<my preference), but this is usually reserved for engines with so much carbon build up it causes dieseling...or continued detonation even after ignition is turned off.
Good luck!
thanks for the tip, I have been running 10W30 oil and an added quart of slick 50. The oil seems too thin now that its warming up outside , I think I will go to the spec 15W40 without the slick 50. How do you do the ATF? do you pour it into the carb the same way you would mist water or do you just add it to the engine oil?
EDIT: Let me rephrase this personally I wouldn't run the ATF in your oil for any extended lenght of time, too caustic for that. I have heard of people putting a quart of ATF in during a change...running it for a short time...then replacing it with regular oil to combat major sludge/clog issues.
You can slowly pour it straight down the carb throat while keeping the idle elevated, only takes a few ounces to blow some significant carbon out...it should blow black smoke (shedding carbon) when it turns white you've gotten most the easy to remove stuff, or you can mix some in the gas tank.
Water works as well, but must be appliled in a finer mist with spray bottle. My preference is ATF cause I've done it before...and I'm paranoid about steam coupling with normal blowby in places you don't want, but others swear by it...to each his own. Or you could just use a fuel cleaning treatment like Berryman's (injector cleaner or some such). There is another fairly recent thread about additives to clean your oil system.
I'm guessing you were running rich before your buddy reset the mixture and now a leaner mix is allowing the carbon built up, to burn off.
Funny you mention the 10-30W & slick 50...last two changes I've used the Quaker State 10-30W with slick 50 in it, and I'm not sure I just won't switch back to straight 30HD, or 15-40 like you're thinking (but discussing oil viscosities can be like discussing politics
)...it'll be hot here soon in Tx.
Good luck!
You can slowly pour it straight down the carb throat while keeping the idle elevated, only takes a few ounces to blow some significant carbon out...it should blow black smoke (shedding carbon) when it turns white you've gotten most the easy to remove stuff, or you can mix some in the gas tank.
Water works as well, but must be appliled in a finer mist with spray bottle. My preference is ATF cause I've done it before...and I'm paranoid about steam coupling with normal blowby in places you don't want, but others swear by it...to each his own. Or you could just use a fuel cleaning treatment like Berryman's (injector cleaner or some such). There is another fairly recent thread about additives to clean your oil system.
I'm guessing you were running rich before your buddy reset the mixture and now a leaner mix is allowing the carbon built up, to burn off.
Funny you mention the 10-30W & slick 50...last two changes I've used the Quaker State 10-30W with slick 50 in it, and I'm not sure I just won't switch back to straight 30HD, or 15-40 like you're thinking (but discussing oil viscosities can be like discussing politics
)...it'll be hot here soon in Tx.Good luck!
Howdy Franko:
I'm guessing from your handle that you are working with a '66 engine. Is the Holley you are working with the service carb replacement for the standard OEM Autolite 1100?
What you are describing, with oil clouds on startup, is a classic sympton of bad valve seals. How many miles on this engine? The light weight oil will make it even more noticeable. Going to a standard 30 weight will help a little, but ultimately, you will need to replace the valve stem seals. It is unlikely that tuning the carb would, by itself, cause your engine to smoke more.
The ATF oil is highly detergent and a good cleaner, but not a good oil. For most cases a commercial can of upper engine cleaner, through the gas tank will do an adequate job of cleaning up most engines, with less risk of adding to engine damage. Your choice.
How about giving us more details of what you are working with? It will help us to be more specific in offering suggestions.
adios, David
I'm guessing from your handle that you are working with a '66 engine. Is the Holley you are working with the service carb replacement for the standard OEM Autolite 1100?
What you are describing, with oil clouds on startup, is a classic sympton of bad valve seals. How many miles on this engine? The light weight oil will make it even more noticeable. Going to a standard 30 weight will help a little, but ultimately, you will need to replace the valve stem seals. It is unlikely that tuning the carb would, by itself, cause your engine to smoke more.
The ATF oil is highly detergent and a good cleaner, but not a good oil. For most cases a commercial can of upper engine cleaner, through the gas tank will do an adequate job of cleaning up most engines, with less risk of adding to engine damage. Your choice.
How about giving us more details of what you are working with? It will help us to be more specific in offering suggestions.
adios, David
yes its a 66 engine, What kind of cleaner are you talking about putting in the gas tank? also, how difficult is it to replace the valve seals on this engine? can it be done easily without removing the head? Do you have to compress air into the cylinders individually with the valves closed or put the pistons all the way up with a nylon rope inserted into the cylinder walls
to hold the valve stems in place? Do the umbrella seals have a locking type of ring attached or are they just push on ? I am thinking of doing this soon, It would be great to have a little info on this.
to hold the valve stems in place? Do the umbrella seals have a locking type of ring attached or are they just push on ? I am thinking of doing this soon, It would be great to have a little info on this.
Howdy back Frank:
Is it an auto or manual trans? Is the carb an OEM Autolite or the Holley #1940 service replacement? Do you still have the stock '66 Load-o-Matic distributor? How many miles on the engine?
Yes, either air pressure or the nylon rope will do the trick with holding the valves up while replacing the seals. No, these unbrella seals do not have the locking ring to hold them in place. They just press on over the valve stem and onto the valve guide boss. The downside is a set of seals by themselves run about $20 while a whole valve job gasket set, including the seals is about $50. You will need a valve cover gasket too. This is where a Shop Manual or Chilton's repair manual come in real handy.
If you remove the valve cover you can barely see the valve seals between the coils of the valve springs. If the seals are really bad, they will be in chunks. They can leak like you're describing and still look fairly good. Another inspections is to do a plug check immediately after a hot engine start up. In other words, the seals will leak worst when the engine is hot, shut off and allowed to sit for 10 minutes. Then start up and stop the engine and pull a plug or two. Be careful! They will be hot. IF they are wet, oily you've found your culpert.
If you do the rope trick to hold the valves up, do not remove the spark plugs on the other cylinders as the pressure in some of those cylinders keeps the crank from rotating accidently. Don't ask me how I know.
There are a number of different products available for upper cylinder cleaners. They range in price considerably and all work about the same, to varing degrees. Take a look at what is on sale this week and see if something doesn't hit your fancy and your price range.
Did you get your timing figured out? A shop manual will help with timing specs, distributor and carb settings too.
Keep us posted on your progress.
Adiso, David
Is it an auto or manual trans? Is the carb an OEM Autolite or the Holley #1940 service replacement? Do you still have the stock '66 Load-o-Matic distributor? How many miles on the engine?
Yes, either air pressure or the nylon rope will do the trick with holding the valves up while replacing the seals. No, these unbrella seals do not have the locking ring to hold them in place. They just press on over the valve stem and onto the valve guide boss. The downside is a set of seals by themselves run about $20 while a whole valve job gasket set, including the seals is about $50. You will need a valve cover gasket too. This is where a Shop Manual or Chilton's repair manual come in real handy.
If you remove the valve cover you can barely see the valve seals between the coils of the valve springs. If the seals are really bad, they will be in chunks. They can leak like you're describing and still look fairly good. Another inspections is to do a plug check immediately after a hot engine start up. In other words, the seals will leak worst when the engine is hot, shut off and allowed to sit for 10 minutes. Then start up and stop the engine and pull a plug or two. Be careful! They will be hot. IF they are wet, oily you've found your culpert.
If you do the rope trick to hold the valves up, do not remove the spark plugs on the other cylinders as the pressure in some of those cylinders keeps the crank from rotating accidently. Don't ask me how I know.
There are a number of different products available for upper cylinder cleaners. They range in price considerably and all work about the same, to varing degrees. Take a look at what is on sale this week and see if something doesn't hit your fancy and your price range.
Did you get your timing figured out? A shop manual will help with timing specs, distributor and carb settings too.
Keep us posted on your progress.
Adiso, David
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