MTFCA Forum

My 1915, non starter car, starts ok when the weather isn't humid, but becomes hard to start in hot and humid weather. Any ideas?
Thanks,

Do you have the original wood in your coilbox? If so, the humidity could be causing problems there. The solution is to "bullet proof" your coilbox by installing the modern replacement for coil box wood, a non conductive material which removes the carbon track and moisture problems often found in coil boxes. These are available from the T parts vendors. In addition to replacing the wood, clean all the contacts to a shiny condition and solder all the connections. Search this Forum for past posts on this topic which describe this further.

Keith

I believe Keith has the answer. Aged or dirty insulation anywhere in the high tension portion of the ignition system can cause problems, and humid weather (or rain, or washing the car) will often aggravate the problem. In the case of the coil box, even wood that looks good can have problems, so the only sure cure is to replace it. Coil units need to be kept clean, as does the coil box, the plug wires, and spark plug internal and external insulators. Spark plug wires should not touch one another or anything else, since the insulation is likely to leak, and inductive cross-firing or leakage can occur.

Plugs need to be in good condition with "sharp" electrodes and proper gaps.

The timer needs to clean and in good shape.

I have the plastic wood in the coil box, and my wires aren't crossed, and contact are clean. I will check out the timer.

If you have been running the car and it stops and won't start, or if you stop for a short time such as getting gas or taking a potty break and then it won't start, you could have icing of the carburetor intake. This is why Henry put on the hot air tube from the exhaust manifold to the carburetor intake. Also arcing inside the coil box can be a problem. This can come from dampness in the wood causing the spark to ground through the wood instead of through the spark plug.
Norm

Along with what Norman suggested, check your spark plugs and set gap at 0.025"

Hot air pipe installed, plastic wood, spark plugs properly gaped.

Time to turn on the gas !

Wayne

I've been waiting for info to trickle out and am now prepared to offer some advice. You have not stated which type carb you have...Kingston L-4 is a very different animal than NH for one thing. L-4 is a very rich starting carb which rarely needs choking in anything but cold weather...NH sometimes wants choke regardless. When you have a car which starts hard in warm weather (I am doubting that humidity is really your problem) very often it is in response to the float level...it can be set "perfectly" and yet act very different between cold/hot conditions. I'd be inclined to run the float just a tad lower than it is and see if your warm starting gets easier with a leaner mixture (fuel lower in the jet). If this is a carb which you have to fool with rich/lean once you're driving more than 60 sec, that would reinforce my advice to you, in my mind.

I have an NH carburetor (with one of your valves). I do believe the car is running rich. Thank you for your input.

Once started in hot, humid weather, how does the engine run for the first minute or two?
Does it start easily in hot humid weather after the first start of the day?

I suspect the float level is the answer. The carburetor adj rod seems happy where it is at. The car is not easier to start when it is warm.

I adjust my NH mixture adjuster to suit conditions. It's easy enough to try a leaner setting. Allow for any slack in the linkage.

Wayne, this advice comes from the non gardening radio presenter on a talkback radio forum. If the expert can't put her finger on the sproblem, his advice is "Move house"

Allan from down under.

"Sharp" electrodes? I know that modern day plugs look like the electrodes have been sharpened with a pencil sharpener. bobt

Electrodes should have the same profile as new plugs of the type you are using.
Worn, rounded electrodes are harder to gap accurately and will require higher voltage to fire.

Worn electrodes on older plugs can be improved by carefully filing them to match the electrode profile of new plugs of the same brand and type as closely as possible. Excess filing will cause problems, and plugs will need replaced eventually.

Modern plugs with platinum electrodes may have a more pointed center electrode. This reduces the firing voltage requirement.

Older type plugs cannot be made this way because the sharper point on the electrode will wear away very rapidly and probably overheat under some operating conditions. Do not alter the original profile when filing plugs.

Bending the ground electrode must be kept to a minimum to minimize the chance of the electrode breaking off. Never bend the center electrode.

Got It! Thanks. bobt

DO NOT COME TO SW FLORIDA!

Well, it's not so very hot, but it's a very wet heat....

On initial starts, high humidity might generally be expected to affect the ignition system, while higher ambient heat might be generally expected to affect the carburetor and carburetor settings.
Both ambient temperature and ambient humidity can affect engine operation once it is started, usually before it is fully warmed up.

The carburetor float was too high, I corrected it, and the car is starting easier.