Diagnosis Please!!!!!

[Professor Fate]

Asking for a friend.....

T runs smooth and strong in low range, not even a skip or hiccup....
T once shifted to high range falls on it's face, gagging and hesitating viciously.

WHY IS THIS?

Gas tank vent hole in the cap is open and clear.

[TXGOAT2]

Likely an ignition problem.

[kevinf]

Like I tell my kids start with the simple stuff first.
I like to pull the plugs and get an idea what is going on. Too rich or too lean is quickly fixed.
Next clean the timer and check all connections, at the timer and the coils and coil box.
Next I start it and spray a little starting fluid around the intake manifold and carburetor throttle shaft looking for air leaks.
I am betting as was mentioned it is an ignition issue and that may take care of it.
Good luck and keep us posted,
Kevin

[babychadwick]

If it starts to go then proceeds to "fall" could be fuel starvation. New problem or old?

[Professor Fate]

It's a New problem. First run on a new motor and trans.

[ModelTWoods]

New motor rebuild. Did you, or have you, put it through any 'break in" time ? Could be rings are a little bit tight (regardless of who assembled motor) and jacking up the rear, securely, Starting it up, and letting it get some run in" time, would loosen the motor up. Just a thought.

[TXGOAT2]

If it's a brand-new installation, almost any adjustment, connection or what-have-you could cause problems.

Get it running right, then drive it moderately at various speeds to break it in. No high speeds or hard pulls for a few hundred miles.

I'd use a 5W30 oil in a new motor in hot weather. NO heavy stuff!

PS: NEVER tell a new engine what gear it is in!

[Professor Fate]

New motor rebuild. Did you, or have you, put it through any 'break in" time ? Could be rings are a little bit tight (regardless of who assembled motor) and jacking up the rear, securely, Starting it up, and letting it get some run in" time, would loosen the motor up. Just a thought.

I agree that lack of run in time may be part or all of it. Friends car has not been run that long in the garage.
When I ran in my new motor a while ago, I would run it in intervals of 5 to 10 mins and let it cool off completely in between. It had near 90 mins of jackstand time before it went put the garage door for the 1rst time.
I don't think that's the case here.....

[Norman Kling]

Do you know whether there was any "speed" equipment in the rebuilt engine. Some of those modifications come with a " Package". You install one part without the others and it actually runs worse. It sounds like you have some high speed parts but the slow speed parts don't keep up. Some parts give you more top end speed, at a sacrifice to low speed power.
Norm

[TXGOAT2]

When the problem occurs, is the engine running on battery or magneto?

Is the tank at least half full of fresh gasoline?

Are the carburetor adjustment and spark controsl hooked up and operating?

Cylinder head and manifold assembly torque checked?

Coils tight in coil box?

[Professor Fate]

When the problem occurs, is the engine running on battery or magneto?

Is the tank at least half full of fresh gasoline?

Are the carburetor adjustment and spark controsl hooked up and operating?

Cylinder head and manifold assembly torque checked?

Coils tight in coil box?

Thanks. Passing it on

[Scott_Conger]

In this order:

• intake manifold gasket leak

• marginal spark plugs (Old Champion plugs are best to use to positively eliminate this possibility for trouble shooting purposes)

• fuel level adjusted too low in carb bowl or just plain crappy carb (I think this is the primary bane of all engine-builders when they hear their engine is running poorly under any condition and I am always surprised when I hear a builder shipping a new engine out to be married to an unknown carb...some builders insist on supplying a functioning carb with the engine and I think that's probably cheap insurance for them)

[Scott G]

Hi all! I am the friend that is being discussed.
Motor rebuild has a
-280 cam, mid range.
-High compression head.
-High volume intake.
-Original crankshaft (I was not spending another $1,700 for a scat crank. It was already very expensive.) Also not warranted.
-NH carb.
-4 new coils
-coil box rebuilt with plastic kit.
-Ignition switch cleaned and repaired.
-New plug wires from prior to rebuild.
-New plugs that had been installed before the rebuild, then cleaned and reinstalled on the rebuild
-New commutator and flapper from prior to rebuild.
- timing set as specified, 2 1/2” from bolt center to center of hole on commutator.
-fresh gas
-just cleaned the carb and checked for debris in fuel line, non.
-New cooper manifold gaskets with copper coat.
-Spark and fuel levers are attached and functioning.

When it falls flat, black smoke from exhaust, little to no throttle response.
I just started the car, it ran better, still rough, but had throttle response, and timing response. No black smoke.
The builder recommended one or two oil changes using sae30 non detergent to start, then change to 10-30, 10-40, or 15-40.
No one has said anything to me about just running in the shop for 90 minutes letting it warm up and cool down to set the rings. I will try that this week. I just need to get it near the door so I don’t asphyxiate myself. ‍
I will try to post the video that I just took of the car running.

[Scott G]

I am unable to attach a video.

[Art M]

Using SAE 30 non detergent oil just doesn't seem to make sense in a newly rebuilt engine or any engine that is not worn out.

Art Mirtes

[Arbs]

I have a recent rebuild... didn't get black smoke out of the back, but did see smoke bypassing the valves (coming from the valve cover), and some coming from the oil fill cap. The smoke has taken care of itself with run in and oil changes (5w-30 non-synth for me, with a dose of Zinc additive). Had a rough time in second as well. I've tuned alot of things to get it running as good as it does now but the #1 thing from all of the lists above was the intake manifold not seating 100%. KevinF mentioned it in your thread earlier. I switched from this gasket to this gasket and it made a big difference for me.

Good luck with your new rebuild!

[Scott_Conger]

Using SAE 30 non detergent oil just doesn't seem to make sense in a newly rebuilt engine or any engine that is not worn out.

I would do as the builder advised. This is a tried/true method that some builders have stayed with. It will hurt nothing and it will maintain your warrantee by following their advice. I am certain that they have or will soon, give advice as to what oil should subsequently be in the engine shortly after their designated break-in period or specific other conditions.

Black smoke and floundering is carburetion in nearly all cases...just because the "smoke" has ceased, if you're still being gassed out, the fuel is not being burned completely and unless it is a brand-spanking new rebuild from a known and respected source, it should be changed out immediately for one that is. You do yourself NO FAVORS dumping raw fuel into the car particularly at this stage of its break-in.

good luck

[kmatt2]

First of all , because in a later post you say that it is a newly rebuilt motor , it may just need more running time to loosen up some. Run the motor in neutral for 15 minutes at a fast idle, with out radiator cap, adding water to radiator if motor gets hot. Next take the car for a short drive, try using a little slower throttle advancement and be sure to advance spark on up shift. If problem continues first check fuel system for proper fuel flow then proceed to checking for good spark to plugs.

[Norman Kling]

One thing I have found with my own experience is the "High Volume" intake manifold is at low rpms it tends to run lean. This is like trying to blow out a candle with your mouth wide open. If you pucker your lips you get more air where you want it. So it doesn't suck in the fuel. It will run faster at high rpms but not so well at low end. I used a Holly NH carb. Might work better with a different carburetor.
Another thing to consider is the fuel in the tank. How long was the car parked before you installed the rebuilt engine? If for a long time, it would be best to drain the tank while the car is setting. The newer fuels don't last for very long before going bad. If it was a long period, drain out all the old fuel and replace with new.
Norm

[Scott G]

Thank you for the input!
It seems I might be too anxious to to drive it. I will run it in place to try to set the rings and break in a little before another drive. That’s sounding like the first step.
As I cleaned the carb today I saw spray coming out from behind the identification plaque. I was concerned that there was a hole there that should not be. A friend told me that there was a vent there. If someone wants to confirm that there is a vent hole there I would feel better.
One thing that I will mention is that I had trouble with the stipe camshaft. It seems that it had not been finished at the end where the flapper went on. I had to have the inside of the flapper hole honed to fit the end of the camshaft. I spoke with Steve Lang and he mentioned that some seconds were coming through because of a shortage of cams. Steve did not supply the cam the builder did. So I mention as an FYI, so that we all can check this on any rebuild happening and not need to do the same thing as O needed to do.

[speedytinc]

The hole under the tag is to bring in air for the mixture. Normal & required.

[TXGOAT2]

Driving the car at moderate, varying speeds and loads is the best way to break in the engine.

[TXGOAT2]

Piston ring manufacturers recommend driving the vehicle to seat rings.

You DO NOT want the engine running at any set speed or load during break-in, but DO avoid high engine speeds or sustained heavy loading.

A multigrade oil with a low first number is excellent for break in oil in a Model T.

[Steve Jelf]

I am unable to attach a video.

That's right. You have to post it on YouTube or some other video site and post a link to it here.

-New commutator and flapper from prior to rebuild.
- timing set as specified, 2 1/2” from bolt center to center of hole on commutator.

I believe setting the timing by measuring 2½" is valid only for a stock roller timer. I have never used an Anco timer, but I think you can set it this way: https://dauntlessgeezer.com/DG97.html
I don't know if this has any bearing on your problem, but it can't hurt to check.

[Scott G]

Thanks for the Dauntless Geezer post. I was looking for that one and could not find it at the time I was looking. He is a member of another group that I am in. I am sure he must be here also.
I do have an Anco Timer on my car so I will need to play with that also. It was so much easier to work on when I didn’t have a radiator on the car.
It’s good to know that the hole is a vent on the carburetor, thank you!!
So it’s looking like it may be a timing issue. I knew it had to be either fuel or spark/timing. I will see how that works. However, the car wants to start right away even as it is. I have hope at this point.

[Steve Jelf]

I am sure he must be here also.

Yes, he is me.

[Jugster]

When I've experienced that kind of problem, it's usually because of the timer. I'd say the first step is to clean it.

[babychadwick]

Try running it with the fuel shutoff almost closed and/or screwing your carb adjustment all the way closed. I'm still leaning towards carb. It sounds like too much fuel is coming in as soon as you open the throttle. It's an easy check where you don't have to "do" anything.

[Lil Teezy]

Is your battery really good? Can you run the car on magneto? If so skip this one!
I drive my car on just 6v battery, no mag, no generator which works fine but only to a point. When the battery drains to just under or is at only six volts, say after two nights of driving home from town with the lights on, it still starts, idles and runs fine at low speed but stumbles badly and steadily misfires if I let it into high and try to throttle up with the advance. It acts as if the carb is set too rich, and the exhaust smells gassy. Incomplete combustion! When I throttle back to a low rpm or idle, it purrs again as if there's no problem. It just won't pull with any power at higher rpm even already moving down the road. So sort of an ignition problem even though the coils are well tuned and the timing is set right. As soon as the charger gets it back to above six volts I'm ripping again for quite a few days. -just my limited T experience, but sounds similar... good luck and have fun!
-Chris, in Boulder

[John Codman]

The classic cause of misfiring under load is ignition. Without getting too complicated, the higher the load on the engine the hotter the spark is necessary to deal with the higher cylinder pressures. I would do what I always do in the OPs issues; Fuel, air, and spark. I usually change the order and do spark first because it is normally the easiest. I would pull the plugs and check the gap and electrode alignment; The secondary wires to the plugs are just plain wire so they should be OK, but the insulation is crude by today's standards. Be sure that there is no possibility that there is no arcing either to ground or another wire. I would put the timer fairly low on the list because it doesn't see high voltage and doesn't care about load, only RPM. There are others on this forum who are better qualified to talk about checking the coils. If I think that I have a coil issue, I just call Ron Patterson.

[Will_Vanderburg]

The 2.5 inch from generator spring bolt to timer rod connection is for a roller timer like Ford or Tiger. If you have an ANCO or New Day, they are set differently.

[Scott G]

Steve Jeff, LOL!!! He is you and you is here!!! Love it!!!

Chris, yes it sounds very similar, my battery is a week old, the buzz coils were rebuilt and set at Lang’s. I don’t think they are the problem.

Timer has been cleaned and oiled properly.

Could the old wires be an issue, possibly. I would need another wire harness set to do the net portion. Only nothing seems that bad, of course the wires are 100 + years old. A possibility.

I had to take a day off from this. Getting annoyed! I will reset the timing at this point and see what happens.
As far as break in I can only sit and idle, or drive around my backyard. So breaking in this engine at this time is a moot point. If I can get it running, I will treat it kindly, not sustained high revs, and go up and down in speed and reves. I have broken in two other engines, just not T engines.

Thank you all for the help!!!

[TXGOAT2]

I missed this:



"When it falls flat, black smoke from exhaust, little to no throttle response."


This is a clear indication of FLOODING.


You have a carburetor issue of some sort. (I assume you are not using an electric fuel pump)
The throttle, choke, and mixture adjustment controls need to be hooked up correctly and working as they should.

Running a new engine with a flooding condition is not good. It can be very hard on the new piston rings and pistons.

Flooding can also quickly soot-up spark plugs, including brand new ones.

Correct the flooding issue, clean the plugs, then go drive the car, adjusting the fuel mixture as needed.

[Scott G]

Alright, it’s 10:05pm do you know where your Model T’s are?

I have attempted to time the car as per the Dauntless Geezer directions. It is not even close to starting. Way worse. At 2 1/2” it started right up. We are at 1 3/4” now as a reference, and the flapper is at the top touching the contact for #1 cylinder.so theoretically we are in the ballpark but all we have are strikes.
So what I am thinking is to turn the commutator clockwise to 2” at this point to see if it is better. This may not be proper, however, I would turn a distributor when trying to start and engine and set it by ear. This seems like a similar situation.
Please give me any good thoughts, tips, or advise that might be helpful. Thank you!

[Norman Kling]

Be sure the spark comes AFTER top dead center with spark lever up. If it comes before, you will kick and either break your arm if hand cranking or break the starter if using the starter. It can be a few degrees off, the spark lever will take care of it, but it MUST be after top dead center when it sparks at starting speed. You can check by removing the spark plugs and looking down with a flashlight to see the top of the of the piston while cranking with the switch on battery. It should start sparking just as the piston starts to go down when you are cranking the engine. Each coil will buzz in firing order as you rotate the engine and each one should be just after the piston starts down.
Norm