Where to set your needle value on your carburetor, when engine is running at normal temperature? I turn it in (clock wise) until the engine starts to back fire and then turn in counter clock wise about 1/4 turn. However I sometimes get a miss fire (not back fire) and am wondering if this is normal.
Personally, based on your description, I would try richening it another 1/16th to 1/8th turn and see if the occasional misfire goes away.
They're all different. With some cars you can just set it and forget it. With others you set it one way for starting, then change it when you're driving. My roadster seems to start best at 11/8 to 1¼ turns out and runs best at 11/8 when driving. The method I use to find the adjustment if I don't know it for a particular carburetor is to try starting at 1½ turns. If that works to get the car running, then I turn it in until the engine starts to run poorly, then open until the same, and then back to halfway between where it should run best. Let the engine tell you what it prefers. Once I find that center spot I open it up another 1/8. That seems to lessen the chance of fuel starvation when climbing and overheating from running too lean.
It can differ with temperature, and with altitude. Here's what I do. Cold start. Choke it and if it keeps running, I leave it alone until the engine warms up. Then adjust it. If I choke it and it starts but dies quickly, I will screw counterclockwise about 1/4 turn and try again. After it warms up, I adjust it.
This is how I adjust it when warm. Turn clockwise slowly until the engine begins to slow down, then turn counterclockwise until it starts to lope. Then I set it about half way between.
Usually an occasional misfire or constant misfire on one cylinder is caused by a missed spark. If it just runs rough it is quite often fuel adjustment and if it lopes and you get black smoke out the exhaust, it is running too rich. If it loses power it is usually too lean. If you are climbing a hill, sometimes the car will run better just a little rich but at higher altitude you need to lean it a bit. If you notice that it needs to be richer at idle but leaner at higher speed, look for a leak in the intake manifold.
My T requires the valve to be open less than one turn.
If I open it 2 turns it will not start.
Once it is running I slowly open it until the motor bogs down or runs rough and close it about a 1/4 turn.
There are a couple things that make a difference in where it is best.
The major one is the angle of the taper.
A short taper has a bigger affect per turn on the opening than a long taper.
Another is how well the taper is centered on the shaft - I have an old needle valve where the taper is off center and it is close to impossible to get the correct setting. Sometimes a slight change in position makes a big difference in how it runs and other times it makes no difference.
BTW clockwise closes the valve making it leaner and CCW makes it richer.
Sometimes a groove get worn around the needle where it seats. Screw the needle down 'till it seats and count the turns as you go. Remove the needle and inspect it with magnification. If there is a groove sand it off by holding some 200 or finer wet or dry sand paper and rotate the needle until the groove is gone. Then replace the needle. All of the posts above have given you the correct answers.
Frank, how are you doing? Haven't seen you post for a while. Hope you're doing better. Dave
This shows the problem Frank described, and how to fix it.
This subject seems to come up on a somewhat regular basis, and I am a little surprised that nobody yet has mentioned anything similar to what I do. Yes, I turn it up 1/2 turn or so for starting cold,
+ choke of course. On the road I do two things; I listen to the tone of the exhaust and adjust accordingly. Also I use the "seat of the pants" method. This also goes for the timing. You can tell when your car is running "happy". I tend to lean her out a smidgen on flat ground and richen her up a bit on hills. This has given me up to 28 mpg on a trip. Anybody else do anything similar?
I thought that's what everybody did, though I have heard guys say they never touch the needle valve mixture control, except to choke it.
I would have mentioned that I richen it up a little when starting but didn't want to confuse folks.
Since my needle has a sharp taper I only richen it about 1/8 of a turn when starting and once it is going return it to the sweet spot.
I sometimes lean it out a slight bit once I am cruising down the highway.
About 15 years ago the Landsing Mi T and model A clubs had a shared dooings at a large Ford dealer where a couple of T's gave rides and the model A people set with their car's!! When time to leave the A two women had was running very poorly and the gathering wanted everything from a set of points to a valve job!! I simply reached in and richened the mixture.The A ran better at once and i showed the women how to adjust it for the engine temp!! I do not know but do people really believe Henry built 15,000 000 plus T's and 4 1/2 million Model A's without this feature being needed??!! Bud in Wheeler,Mi.
A lot has to do with Ford sticking to the type of carburetors used on the Model T and A. While other manufactures, even in the low cost field, were using set it and leave it carbs like Strombergs and Tillotson Ford went with carbs that needed drivers fiddling with them to run the car. Part of the fun in driving T's, oh wait, I am running a Stromberg!
Depending on your carb, choking is part of the starting process. The choke is used to prime the motor. A couple of revolutions with the crank or starter is generally enough. Some carbs/engines need to primed even when hot some don't. Also some need the throttle butterfly closed and some open just a bit. Experiment till you find what works best.
Thanks again to all who took the time to answer.
ps; I have installed a new set of spark plugs from Lang's
Warren - Which plugs did you get?
Fred, I bought Champion 25, non-original style, item # 5201 from Lang's.
I've found those Champion 25 plugs are too cold and tend to foul quickly. My life as a T owner became free of fouled plugs when I began using only old used Champion X plugs. Like these:
I never bid or pay more than $5 per plug.
Ok I currently have a set of Motorcraft plugs and just ordered Autolights to see if there is a difference.
I set the gap at 032 but someone said that 027 is better.
What do people recommend ?
Fred: Mine are set at .025" >>>Easy starting & good power. Your mileage may vary