Spark lever position at idle and temperature sensitivity
 

I have two questions:
1. How far down do you put your spark lever when you're idling?

2. How sensitive is your car to temp swings day to day?

I'm trying to get that nice low classic Model A idle and avoid gear clash when putting it into first when stopped. I'll get it set nice one day. Then the next day the temp will drop or rise 10 degrees and either the idle quality will drop and it'll miss intermittently or the idle speed will be higher than it was previously

Are these really that sensitive or am I doing something wrong? I only make adjustments with the car fully warmed up and I never have to adjust the fuel screw more than 1/3 of a turn or the idle speed screw much more than 1/8 of a turn.

I generally keep my timing lever ~1/4 way down at idle. Thats where I keep it when setting my idle too. I've gone through the whole ignition system and have initial timing set to 0*, I have a marvel carburetor on it which has been gone through and cleaned as well

Re: Spark lever position at idle and temperature sensitivity
 

I normally do not move my ignition lever when idling. I set my idle speed with the ignition advanced to the normal operating position so the idle is slow then. I have to set up my idle with the hand throttle when the engine is first started and not warmed up yet. I have a 6.5:1 head.

I will retard my ignition slightly ( about 3 notches) when trying to drive slowly or up my steep driveway. I will retard it all the way and set up the hand throttle a bit if I want to do the chug-chug thing (for my own entertainment). I time my distributor 3 notches down so the fully retarded position is really firing way after top dead center.

Re: Spark lever position at idle and temperature sensitivity
 

With my 6:1 head, touring cam and electronic ignition I run the lever at 9 o'clock. Sometimes putting around town I'll run it at 10:00. For parade mode ignition down 2 and throttle 4. It will crawl along there (out of OD) but sometimes will buck if we get a little incline. Mine has a pressure radiator and 160 degree thermostat and always runs right at 160. It did get to 165 on a hot summer day when I was running 65 mph on the freeway.

Re: Spark lever position at idle and temperature sensitivity
 

9 o'clock meaning halfway down right?

Sounds like I'm setting my idle with the lever too retarded. Do either of you experience issues with temp swings drastically affecting your idle quality?

Re: Spark lever position at idle and temperature sensitivity
 

I’ve said it before, where the lever sits depends on the car and what position you set your rotor on. Ignore the 9 o’oclock, 10, etc. if you’re running hot, try advancing the lever or richening the GAV. Monitor your fuel economy, you should be getting nearly 20mpg. Less, look to advance the timing some more.

Like others mentioned, I don’t move the lever once it’s warmed nd ready to roll. Maybe on long pull at highway speeds if it knocks.

Re: Spark lever position at idle and temperature sensitivity
 

Now and then, I retard at idle to show folks how low the rpm will go but I don't make a habit of it. They like a normal idle rpm for good oiling.

Re: Spark lever position at idle and temperature sensitivity
 

With a STOCK head- When the engine is warming up at high idle, 5 (out of 10) notches from top. When running around town, 8 notches down. When on the highway, 10 notches down.

With higher compression heads, they will become more picky. The higher the compression, the more picky. I prefer the stock heads.

Re: Spark lever position at idle and temperature sensitivity
 

Last rough estimate I did, I was getting about 17mpg. But, I just got my speedometer/odometer working yesterday, so I'll be able to get an accurate MPG rating now. Thank you hitman

What is considered a "normal" idle speed?

Since I got the car I've had it set to around 700rpm fully warmed up. It just seems high to me, the gears clash putting it into 1st from a dead stop. I've read people say anywhere from 400rpm to 600rpm.

Re: Spark lever position at idle and temperature sensitivity
 

700 rpm’s are high, set it as low as you can, you can always use the hand lever to increase the idle. Clashing gears going into 1st sitting still may indicate clutch issues, push the clutch in and count one thousand two thousand three thousand and then put into 1st. Then you adjust the idle speed adjust the idle mixture

Re: Spark lever position at idle and temperature sensitivity
 

Mine at 550 rpm with spark lever in driving position and engine warmed up. As stated above, I have a 6.5 head (on my car).

The higher compression head promotes faster burning of the air/fuel mixture. As the rpm increases the burning is faster so that I rarely move my spark advance lever. I will move it one notch more retarded if lugging at lower rpm and one notch higher is cruising down a level highway.

I keep a log book with the gallons bought, mileage, and date, and a note about what I am doing at the time, such as highway travel or back roads. I also note any changes to the car like changing tires or repairs or adjustments. My mileage varies from 16 to 20 mpg depending on how I am driving the car.

Re: Spark lever position at idle and temperature sensitivity
 

how much wiggle in the throttle shaft, if worn the the throttle may not close at the same position every time

Re: Spark lever position at idle and temperature sensitivity
 

Kurt, That is a good suggestion. In addition, Bandit's throttle linkage may not allow the carburetor idle speed screw to fully control the setting. I had that happen to me and had to bend the arm on the throttle shaft that crosses in back of the block.

Re: Spark lever position at idle and temperature sensitivity
 

The throttle not closing fully every time was my first thought. I put a spring on the end of the throttle linkage arm that pulls it shut.

I set the clutch pedal to one inch free play. It doesn't take much force to get it into first, it's just a quick double clunk going into first.

Re: Spark lever position at idle and temperature sensitivity
 

I have a Fordor, completely stock with Zenith and stock head. Here's how I run mine: Advance the timing lever so when pulling a hill, you hear it just start to ping. Retard it a click or two until it doesn't ping anymore. Remember that position. As soon as you start the car pull the lever down to that position and leave it there. Set the idle speed so when the throttle lever is all the way up, the car is running as slow as it will run without dieing. Then when running the car you have control of the idle speed via the hand throttle. I keep my idle very slow, it makes all shifting much easier. After the car is warmed up, set the GAV for smoothest idle, then for cruising close it a bit until you feel it leaning out too much then open just a touch. When you are back in town or slowing down to turn/shift, open the GAV again to the position you set it for idling. The "classic" Putt Putt of a retarded engine is OK, but serves no purpose except for listening enjoyment. I never run mine on a regular basis with the timing retarded. As far as missing and idle changes at different temps, my car does not do that. I'd try swapping out the carb with a known good one, also check for warped pot metal carb body and poor gasket between carb and intake.

Re: Spark lever position at idle and temperature sensitivity
 

Also if the edges of the butterfly valve are worn near the throttle shaft it will cause the butterfly angle at the idle fuel ports to be wrong, the idle port get covered more changing the mixture with un metered air

Re: Spark lever position at idle and temperature sensitivity
 

UPDATE:

Problem located and temporarily solved. Unfortunately, I found this problem because another problem popped up. I went into the garage this morning and noticed a strong smell of gasoline. A very slow drip coming out of the mouth of the carburetor. Just enough to wet the engine pan, but there wasn't anything on the rug that I park the car over

The fuel petcock in the cab isn't quite stopping the flow of gas. I took the carb off and the fuel line had a very slow Drip coming out. There was a bunch of sediment in the bottom of the carb and I guess some had worked its way between the float needle and seat too which kept it propped open.

Took the carb apart, double checked the float height and cleaned everything out. Set my idle speed to ~600rpm with the spark lever set halfway. Idles nice and now I've got the gas line disconnected and capped off. Next step is to replace the petcock and figure out a way to clean the junk out of the bottom of my tank.

Oh well, if the car didn't have any problems then I wouldn't have anything to on my days off.