Surging?

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colonelpowers
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Surging?

Post by colonelpowers » Sun Mar 26, 2023 8:35 pm

I thought I would check in with the experts before I take to tinkering tomorrow. Not too much to my dismay at the moment all of our modern vehicles are having issues so our 26 touring has had to step up to fill the void. Today I had to run to Wytheville (about 60 miles roundtrip) to get some feed for our mules. Going there I noticed what I perceived to be a faint rhythmic surging feeling in the car. I honestly discounted it as nothing and figured that it was something related to the ancient Ward's Riverside tires which are still "good" but are pretty rock hard. Coming home and pulling hard up some pretty steep hills the surging became more noticeable. Its cycle was steady and probably every second or less. I still high geared the hills. As I got closer home and had to turn on the lights it got worse still. After I unloaded the car and went to put it away, though dark I listened carefully to the idle and couldn't detect a miss but when you give it gas it is very slow and rough to accelerate. In Wytheville I did a similar check and it seemed okay.

The old car is and with ancient, with possibly original wiring. It has a restored generator and rebuilt coils. The ignition switch does have at least one problem in that it will not make contact on the magneto side. I recharged the mag and it produces very strong voltage but when you flip the switch, nothing. One last thing of mention is that I always had a couple amps charge showing on the amp gauge. With the lights burning I had a 10 amp discharge. The timer is an old roller style that was recently oiled.

Any ideas will be app, especially since it is a point of great pride lately for me to brag that the only vehicle that I can rely on is nearly 100 years old. Am feel sure it is something simple like a fouled plug or a grounding wire.


speedytinc
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Re: Surging?

Post by speedytinc » Sun Mar 26, 2023 8:51 pm

Sounds like fuel starvation. Happens @ highest fuel demand. If your T was a pre 26, I would say so with more confidence. The normal, dealer provided needle & seat units have too small a hole for free flowing fuel. Generally not an issue on a 26 with the cowl tank.
Check the filter screen. Drain some fuel from the bowl (sediment & carb.)into a glass jar looking for trash.


TXGOAT2
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Re: Surging?

Post by TXGOAT2 » Sun Mar 26, 2023 8:52 pm

I was thinking maybe your battery was getting low, but a 2 amp charge should eliminate that. You might check the tightness of the intake/exhaust manifold assembly fasteners. A worn or gummy timer might be something to check for.
I'd also check the fuel screen/bowl and try draining the carburetor and checking for free fuel flow. Diminished fuel flow might cause a mild surge.
It's possible the points accumulated some oxidation and need a light filing, and coil box contacts along with the snugness of the coils in the box are easy to check.
A smooth, light, cyclic surge could point to a fuel issue, either too much or too little.
Is it possible your carburetor adjustment is "creeping" due to normal vibration, and going rich or lean? A lean condition would probably provoke a pop from the carburetor, but a rich condition could produce a mild, rolling surge with no pop or backfire. A choke that was not opening fully, or not staying fully open, could also cause it.


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Re: Surging?

Post by TXGOAT2 » Sun Mar 26, 2023 8:56 pm

If running the lights made it worse, it could point to a low voltage problem. Even a slight ignition system issue combined with low system voltage could produce a noticeable issue.


speedytinc
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Re: Surging?

Post by speedytinc » Sun Mar 26, 2023 9:00 pm

If the timer contacts are not smooth, the brush can bounce @ higher RPM's.


J1MGOLDEN
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Re: Surging?

Post by J1MGOLDEN » Sun Mar 26, 2023 9:10 pm

I would suspect a rebuilt carburetor would cure your surging problem, as it might be flooding or not having enough fuel storage when more is required.

Your generator should be charging about 9 amps maximum.

Your head light will require 9 to 12 Amps, depending on what bulbs you are using.

LED lights cost more, give more lights and take a lot less current.

Driving at night or when the head lights are on will always take a little more current than the generator can produce.

The difference is minor and will normally never drain the battery enough to keep the engine from starting again.


Topic author
colonelpowers
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Re: Surging?

Post by colonelpowers » Sun Mar 26, 2023 9:52 pm

A couple folks mentioned possible fuel/ carb issues which I will check tomorrow but I did forget to mention that I have a restored Kingston carb and a new sediment bowl. Also, and I know it is not the best idea, I put a temporary fuel filter in the line. It is a riding mower filter so it is a little higher flow than some. I have driven a few hundred miles with it on the car just to be sure that there wasn't any trash in the tank. Supposing that it was a fuel issue, could that problem really be magnified by the amperage drop caused by the headlights.

Someone mentioned corrosion on the points which I will also check but the coils were rebuilt recently so I would hope that wasn't the case.


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Re: Surging?

Post by TXGOAT2 » Sun Mar 26, 2023 10:03 pm

I would immediately suspect the added fuel filter. They are known to cause issues, and if your fuel system is the least bit dirty, the small filter will be quick to get restricted. If your stock fuel outlet and screen are in good shape, an additional filter should not be needed. A dirty fuel tank will be an on-going headache no matter what kind of filter you use. Another problem with small, paper type filters is that if any moisture is present, many of them will absorb the moisture into the element and that can restrict fuel flow or even stop it.


speedytinc
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Re: Surging?

Post by speedytinc » Sun Mar 26, 2023 10:28 pm

Electrical & fuel are not related. Loose the filter.

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TRDxB2
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Re: Surging?

Post by TRDxB2 » Mon Mar 27, 2023 2:37 am

Fro what you said
"One last thing of mention is that I always had a couple amps charge showing on the amp gauge. With the lights burning I had a 10 amp discharge." This somewhat expected. Ammeters aren't that accurate. Filament bulbs take about 2+ amps each - so that's 6+ more when turned on.
--
"I put a temporary fuel filter in the line. It is a riding mower filter so it is a little higher flow than some."
Likely the issue. There are several riding mower filters (some looking alike) but rated for different HP engines.
These have a simple round mesh much like what's in the sediment bulb but a finer mesh and in some cases requiring a fuel pump. Any of the cylinder types are likely requiring a fuel pump
As an example of similar ones
mower filters.png
--
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Then there's this - but what is "low pressure"?Atmospheric with gravity assist?
K&N filter.png
The past is a great place and I don't want to erase it or to regret it, but I don't want to be its prisoner either.
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TXGOAT2
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Re: Surging?

Post by TXGOAT2 » Mon Mar 27, 2023 10:54 am

I would see if the tank needs cleaned, and if it is reasonabley free of debris, a mirror can be used on a sunny day to look into the tank for evidence of rusting, dirt, or fine debris suspended in the fuel. Do not use a flashlight! Have the tank full, and shake the car to stir up fine particles, then use the mirror to reflect sunlight into the tank. If the tank is reasonably clean, the stock type screen and bowl will be entirely sufficient.

Physically small filters have a very limited capacity to collect debris or moisture without becoming restricted or outright plugged. Any added filter will add restriction.

An added filter is not necessary, nor is it a good idea on a gravity feed system, and it's an especially bad idea on a Model T with an under the seat gas tank.

Be sure that the vent in your gas cap is not plugged or restricted.

A gas tank that has water or fine rust or any other debris in it will cause you problems no matter what kind of filter or filters you use. With that said, the best filter for a dirty system is the one Ford originally used, which has a bowl to collect sediment and moisture.

The next best choice would be a tractor-type filter with a deep glass bowl, and it should be mounted in the same location as the original Ford filter/bowl unit.

A stock type filter that needs frequent cleaning indicates that the fuel tank needs cleaning.

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