Hey guys, I'm kinda stumped. I just got my G'pa's 24 Roadster. The belt broke and I replaced it...the car was running fine before. After replacing the belt, cylinders #1 & 4 are not firing.

The way I determined that these 2 were not firing was running a screwdriver from the top of the plug to the block. Those 2 had no effect, when doing that to 2&3 there was a notice left difference.

I know that the belt was close to the commutator when I routed it, I have checked all connections and they all seem to be fine.

Not sure where to go from here, I am new to all of this T stuff. Any help would be appreciated.

Thanks!!

Check the timer to see if the belt hit the wires when the belt broke. It may have knocked them off.

Dennis W.,

Try swapping the coils around to see if the problem travels with them. Also, if you crank the engine around slowly, do coils #1 & #4 even buzz?

All of the wires seem to be intact and connected well.

Jerry, I can hear all 4 coils buzzing as I cranked it.

Dennis,

I assume you mean one coil at a time?

Try the coils swap next.

Jerry, yes. As I hand cranked the engine around I could hear each one buzz

Don't be surprised when you track down the cause, and you find it has nothing to do with the fan belt. Check that your wires are in the right order. Looking at the timer from the front, starting at the 11:00 position, the order should be 1-2-4-3, going counter-clockwise. Your coils are 1-2-3-4, from left to right looking at the firewall. Spark plug wires are 1-2-3-4 front to back. When I got my 24, the previous owner, for reasons only known to him, had a couple of the timer wires backward and the corresponding spark plug wires switched as well. When I changed the plug wires, I got all kinds of kick back and back fires until I traced the connections.Verify those connections and also make sure the inside of your timer and roller or brush is clean. Roller timers like to be clean and lubed (there are plenty of threads about that) and brushes need to be clean and dry.

James, I know everything is routed correctly, the car ran great before....but I did double check. Ha.

I will check the roller timers.

Most, if not all Model T's won't even run on 2 cylinders !

I switched the coils. 1 with 2 and 3 with 4. Still runs rough, and jumping from the top of the plugs to the block, #'s 1&4 still has no change to the engine.

Even though jumping 1 and 4 to the block and is has no effect on the running....you do see spark jumping.

So the problem stays with cylinders 1 & 4 when coils are swapped. You also are getting spark energy to the plugs on 1 & 4, so coils 1 & 4 seem to be OK, but those cylinders are not firing. Take a look at plugs 1 & 4 next? Seems odd that they would both go out at once.

I have pulled, cleaned, and switched all plugs with no change.

I'd pull the plugs and lay them on the head and turn the engine over by hand and see if you can se them spark. If all four are sparking, they maybe stuck valves. Nothing to do with fan belt.

Or is car starting and when adjusting spark rod, it got bent and is shorting out on two terminals off the terminal cover?

Robert, I laid the plugs on the head. They all had spark.

It doesn't have anything to do with spark rod adjustment. It does it before rod is adjusted.

What is the easiest way to check for stuck valves?

Compression test. You can even do it with your thumb on the plug hole. Compare the pressure from the two good cylinders with the pressure from the troubled ones.

When something like this happens, I refer to an old adage; when something goes wrong, check what you did last. Like you have said, it ran well before the belt broke. Because of that, I would check again the connections to the timer and by all means check to see that the timer didn't dislodge and the roller is not firing at the correct point on the timer. Just a thought. DickC.

Val, using the thumb method the compression seems great.

Dick, the timer seems to be tight, tried moving it with my hand and no movement.

Is it possible to have a plug wire strong enough to see spark but still weak?

Yes. Seeing a spark with the plug out doesn't mean it's an adequate spark under compression. Another thing to check: are the plug wires soldered in the terminals? Many are sold unsoldered, and they work loose.

Steve is incorrect. I don't know whether a T will start on one cylinder, but I can hold down the vibrators on 3 coils and the engine will still run on one cylinder. I can do that with each cylinder after the engine is running.

I would suspect that something happened to the wires connected to the timer at the time the belt was replaced. However, it could be a co-incidence that the problem started at the same time.
Norm

Try the easy things first. Try adjusting the timing lever and air/fuel mixture some in both ways to see if the engine smooths out.

Does it run on mag? If so does it have the same problem on both bat and mag?

Jim

Thanks for all of the info guys. I am new to the car, and if nothing else, I have learned a lot with all of your suggestions.

I have noticed what appears to be a weak spot in one of the plug wires. I have a new set ordered. I think I am going to wait a couple of days until I get those and see what the result is.

I will let you know at that time if I had any luck, or beg for more help. Ha!

Thanks again for all of the info!!

Coil box maybe?
When the fan belt was changed some of the wiring going to the timer was pulled around or something?

Is it the original wiring? Whatever happened it probably was something to do when the belt was changed. Its probably something pretty simple and right in front of your eyes.

T's can be quirky at times and now its your T's turn! You'll eventually figure it out!

Jim, the problem occurs on both mag and battery.

You didn't by chance wash the car, did you? Or get it wet in the rain? I had an issue with a carbon trace in a coilbox.... car ran great, I'd wash it and it would run like crap for a couple of days. It didn't take much water to make it happen. Got the heck shocked out of me with the box one day and found it! I installed one of the Fun Projects coil box kits and the problem went away.

If you do decide to work on the box that kit is worth every penny! Coils fit better too. Take the time to really clean all connections in it, and to solder the bolts to the contact strips.

As some have mentioned the possible problem could be the coil box. To test the coil box switch the timer and spark plug wires in positions 1 and 2 and 3 and 4. In other words the number 2(or 3) position of the coil box will be firing the number 1(or 4) cylinder. If the weak cylinders are still 1 and 4 you will have pretty much eliminated electrical issues.
Jim

Laying spark plugs on top of the motor so you can watch them spark is a meaningless test which proves absolutely nothing and generally results in absolute proof of misinformation. From that point forward the hunt proceeds into tall grass.

Tall grass!

I have a tendancy to talk just to have someone to listen to, so forgive me if I'm off base. When we first got my T engine going for the first time for me, I thought it was running great and a video posted here resulted in the conclusion that we were running on two cylinders. Exhaust valves stuck on two cylinders. We removed the valve inspection covers and hand cranked the engine and my son noticed the two stuck valves. Removed head, inserted shims and hand cranked the stuck valves out, cleaned them up and put them back in and we've run great ever since. I'm no mechanic, but I don't know enough about the internal combustion engine to know if two exhaust valves stuck would show up on the thumb compression test.

If exhaust stuck open, which it woud have to be to be stuck, would that prevent compression? What if, God forbid, they are broke and stuck in the closed postion. Still get a thumb compression?

I agree with most that this certainly seems spark related, but it sounds like you've troublehooted the obvious culprets. If you think you have a bas spark plug wire and have ordered new one, what happens if you just switch that wire with another one on your car that you know works. Does the problem follow?

Robert, both valves need to be closed on the compression stroke and if either one is not fully closed compression drops.

Makes sense. Thanks. Didn't mean to hijack the thread. Hope we can track down the "missing" two cylinders.

Ok.. I pulled the timer(?) off and it looks like the contacts are worn and "melted" into each other??

I will post pics and see if you can tell what I am talking about.

With all due respect to the more knowledgeable posters, laying the spark plug on the engine and turning it over is a very helpful start to locating an ignition problem, if you are getting a spark at the correct location in the correct sequence that establishes you have the basic wiring and sequence, if not then the real trouble shooting begins!

For some reason it is not allowing me to post a pic. But you can see all 4 of the contact points and it looks like they have have been "hot" and have been drug/melted. It is hard to explain...it looks like the whole surface the roller rolls on is the same material as the contacts like it has "smeared " the contact points.

I'm sorry if my description is bad..really wish I could post a pic.

***********You need to clean your timer!************

Does not matter if it's the brush or roller type your description tells me it dirty. Cleaning the timer is part of the regular maintenance of the T. If it's the roller type clean then lube with a non graphite type grease (the red type grease works fine) or even oil thru the oil hole. If it's a brush type just clean and install dry.

I did get the timer cleaned up. I should have a chance to install it when I get home from work.

How much do I oil it? How often should it be oiled?

Dennis,

As to oil, it depends what kind of timer you're using. Some need oiling, others not. Photo?

Jerry, I can tell you it has a roller in it. I am not having much luck posting pics, but I will try when I get home.

All roller timers needs lubrication. Lots of it

Excuse the dumb question, but how are the spark plugs and coils firing, if the timing cover is all gunked up.

Out of sequence due to the gunk?

Robert, they were firing in the correct order.

Ok....The timer is all cleaned up greased and reinstalled. I did have something messed up when i put the wires on it. Got all of the wires in the right place on the timer, they are firing in the correct order now. New plugs and wires, and it still runs terrible.

I believe that I am now completely lost!

How old are the intake manifold gaskets?

Dennis, post a picture of the inside of your timer.

Stephen

Some have problems with grease in the timer - others recommends it. Can't be too hard grease or the roller wont make proper contact. So if you have problems, then wipe it out and try oil instead? Also check the spring on the roller so it pushes the roller out towards the timer case.

Well guys, problem solved!!! I can't thank you enough for your help!

I believe the timer was the issue. In the middle of trying to figure out what my problem was a buddy of mine stopped over. After the timer was cleaned and reinstalled the car still ran horrible....I was lost! Then all of the sudden I noticed the idle air screw closed! Apparently when my buddy was checking out my car he had to fiddle with something!

I can't thank you guys enough for all of your help... as far as my buddy...I will deal with him later. Ha!

Thanks again guys!

Glad you got it resolved.

Idle air screw? What kind of carb?

I'm not sure if idle air screw is the right term... it is the air control screw in the manifold.

This is why I love specialist forums. I don't have this problem and hope never to have it, but reading through this thread has given my years of anecdotal experience that money can't buy :-)

Glad to hear the problem is fixed and a 3rd party thanks to all who contributed.

Well.. the car idles fine, I just took it out for a drive and it does not seem to run well in low gear. It seems that once I get to high gear it is ok.

Sorry guys...I thought i was done begging for help at least for a little bit. Ha!

Interesting! it sounds like some kind of period accessory, can you post a picture of your manifold with the air control screw?

Mark, I am trying to add a pic, but it is telling me the file is too big.

There is a file size limit of 250K per picture on this old forum software.

You can use Paint or another photo editing software package of your choice to reduce the file size of your photo. Make a copy of your photo and reduce the size of the copy so that you still have your original, full resolution photo.

Dennis, it looks like you'll need to turn the handle on that valve 1/4 turn so it's parallel with the intake manifold. Right now it' s open and creating an air leak into the manifold.

Does the valve suck air when the engine is running?

Eric, it was closed. I had to open it like that to get it to idle right.

yes

Hmm - although there were aftermarket accessory "vacuum leaks" offered in an effort to improve mileage back in the day, the car should run fine without it.

There may be one or more passages in the carburetor blocked by rust or other debris.

As long as the car runs fine with your current setup, enjoy it, but if you ever decide to go through the carburetor and those passages get opened back up, you may find that you won't need to have that valve open any more.

The car is running very bad in low gear. It seems to be ok in high gear.

The engine is running faster (demanding more gas) in low gear.

Try to separate out the engine from other issues by running with no load on level ground at the same engine speed in both low and high gears. If it really is an engine problem, then it should run just as bad in high gear as in low gear (the car will be going faster in high gear at that engine speed, of course).

It is running bad enough that is hard to keep running just driving up and down the driveway. There is a lot of smoke from the exhaust.

I have not hard the carb off. I'm guessing that is the next direction.

Sounds like you're running too rich, hence the need to open the air valve on the intake manifold.

How far out is the mixture screw turned on the top of the carb? Count turns while turning it clockwise until it is LIGHTLY seated. Don't tighten it down too hard, or you can damage the needle on the end of the screw.

1 1/2 turns is a good starting point if your carb is working properly, but you'll have to fine tune from there.

Mark, I did open the valve back up, and double checked the mixture screw and started 1 1/2 turns out.

It does seem to be better, but still not quite right. I am sure it probably isn't adjusted to the sweet spot, and I'm sure that I am part of the problem also. Being new to the car, and to T's in general, I am sure that I am not driving it right as far as where the fuel and spark lever are while driving.

Dennis,

In short, that valve does not belong there, although lots of T's seem to have them. It is not a factory item and should be closed at all times.

1-1/2 turns is an estimate. You probably will end up needing less than that when everything is o.k. Looks like you need to clean the carburetor. Something is running very rich and you're applying the Band-Aid of that "air valve" to compensate. That will never be a workable solution.

Check for proper fuel flow. Some of the sediment bulbs were found to have the handle and hole not in line so when you think it's open it's only partly open creating a carb that is starved for fuel. Have you cleaned the screen in the bulb? Do you have an additional filter in line? In line filters create many fuel flow problems and aren't necessary.

Thus my earlier question regarding how old the intake gaskets were, before you mentioned the valve on the manifold (which doesn't belong there). All of your trouble sounded more like carbonation than electrical, to me. As others have said, close that thing and get your carb adjusted/fixed. And while you're at it, save yourself future grief and replace the intake/exhaust gaskets with a quality product (don't use the purely paper version). Cylinder 1 or 4, or both, not firing well is classic vacuum leak at intake.

Dennis W.,

To expand on what Scott said, you probably have a vacuum leak causing 1 & 4 to miss. Those run a bit leaner anyway, so they're the first affected by a vacuum leak. To compensate, the carb gets adjusted richer than normal, but now 2 & 3 get flooded. The air valve becomes the "fine tuning" to balance the two, but as I said, it's not a solution.

Anyway, do what Scott Conger suggests.

Use this kind of manifold gaskets:





AND DON'T GET DISCOURAGED!!!

Thanks for all of the advice, Gentlemen! Before i saw your posts about the manifold gasket, I pulled the carb off.

What should I be looking for in the carb?

I did previously spray some WD40 around the manifold.... would that have indicated a leak?

Be sure to clean and gap your plugs. Probably not your problem but for me at least 1 & 4 seem to foul the easiest if you start the car and let it idle without getting up to operating temperature.

There does appear to be a groove in the tip of the needle.

A vacuum leak may indeed be the problem. (It wouldn't hurt to use a little hi-temp RTV when you install those manifold gaskets.) But the grooved spray needle sure doesn't help. Fortunately, that's easily fixed:

https://www.youtube.com/watch?v=uTiStUTU9IE

Awesome info Steve. Thank you!