No condenser??

[Chris Halsey]

HI folks,

New to the forum, recently bought a 1929 2 door coupe from a widow and have been trying to get it to run. So far, have done the usual things, drained the gas, cleaned the points, etc. It will now start and run, but only for about 30 seconds or so. Thinking may be rust in the tank clogging the tank filter...maybe..

One unusual thing I saw was that it does not have a condenser, just the empty hole under the distributor.

I guess my first question would be, what is the condenser used for, why would it be missing from my car, and could this be why it is running so poorly?

Thanks for any and all info, it is appreciated!


Chris

[RonC]

The engine needs one to run properly. It would need to be anywhere between the coil and the points. Look next to the coil on the firewall or under the capon the top of the top plate. If missing install one.

[gweilbaker]

Without one, your points will fry in a heartbeat.

[MrTube]

I am not 100% sure, however this is what my understanding is.

The condenser does not change how the engine runs in any way. What it does do is keep the points from burning. When you close the points it runs current through the coil. When you break the points apart it causes an abrupt interruption to the current through the coil which causes it to fire the spark plug. At the same time, inductors (the coil) do NOT like a change in current, they will do everything they can to keep the current from changing which usually is seen as a huge spike in voltage, or an arc. When this happens, the condenser absorbs this change in voltage preventing the arc from starting across the point gap.

Again, this is only my understanding and I may be wrong.

[28Annie]

Most likely the person who previously owned the car used what is known as a "modern" style upper plate, so the condensor is moved from the housing (where you now see the empty hole) to the upper plate inside the distributor cap. What many people do to retain the original appearance & to fill the empty hole is just trim an old condensor to plug the hole.

Best of luck with your new ride!

[cp5491r]

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Yes- the first place to check is on the upper plate inside the distributor. It reduces the exposure of engine heat to the condensor and extends its life.

[P.S.]

I'll try and un-engineer this as much as possible.

When you create a high potential spark through rapid discharge of a coil, it is not only higher voltage, but an alternating current at high frequency. The frequency itself is determined by the inductance and resonant frequency of the coil. The condenser is an "RF bypass" to sink the high frequency and voltage potential on the primary to ground instead of allowing it to build up enough to jump across the points the way it does the spark plugs. That would be catastrophic. It could also cause early coil failure caused from arcing of secondary to primary.

It also allows an "anchor point" (if you will) for the potential to work against, if that simplifies things further.

It's a good thing that the spark created by your ignition system is high frequency instead of DC or 60 Hz. Otherwise, getting across the approx. 20 KV wouldn't just be a painful jolt as it is at high frequency, it would be instantly lethal.

Really high frequency sparks are something the Tesla coil fans mess around with quite a bit. That's a whole different story.

[MrTube]

Originally Posted by P.S.

I'll try and un-engineer this as much as possible.

When you create a high potential spark through rapid discharge of a coil, it is not only higher voltage, but an alternating current at high frequency. The frequency itself is determined by the inductance and resonant frequency of the coil. The condenser is an "RF bypass" to sink the high frequency and voltage potential on the primary to ground instead of allowing it to build up enough to jump across the points the way it does the spark plugs. That would be catastrophic. It could also cause early coil failure caused from arcing of secondary to primary.

It also allows an "anchor point" (if you will) for the potential to work against, if that simplifies things further.

It's a good thing that the spark created by your ignition system is high frequency instead of DC or 60 Hz. Otherwise, getting across the approx. 20 KV wouldn't just be a painful jolt as it is at high frequency, it would be instantly lethal.

Really high frequency sparks are something the Tesla coil fans mess around with quite a bit. That's a whole different story.

P.S.,

Are you sure about this? The reason I ask is as far as I know the polarity of the coils output never changes therefore it couldn't be considered alternating current.

[P.S.]

The polarity of the primary doesn't change, it is DC.. When the coil (inductor) field collapses upon sudden removal of DC from the primary, the violent discharge is not 'pure' DC. There is a high frequency alternating current component to it.

Well, you could consider it a pulsed DC if you want, but going from 0 to 20KV in a very rapid fashion over and over is (in the spark transmitter world) considered AC.

[Chris Halsey]

Thanks for the input folks. As it runs for 30 seconds to a minute each time, there must be a condenser there someplace. I'll mosey out to the garage and see if its attached to the top plate under the cap. Think I would have noticed that when I cleaned the points, but may just have slipped my mind....One way to find out.

Thanks again folks, very much appreciated!!


Chris

[Mikeinnj]

Chris, getting back to your original statement, ....if the engine runs for 30 seconds, you have fuel , spark, and compression. Now it's a matter of finding which of those components is quitting after 30 seconds. I would start with the fuel. Disconnect the line at the carburator and empty fuel into a container (no sparks,or heat) and observe that there is an uninterupted flow. If it is good, then check inside the carburator, some models have an internal filter where the gas line connects. Examine the filter for debris. Next remove the bowl (lower half of carb) and check the fuel float for the correct height. If too low, reset it and also check that the needle valve is not sticking closed and running the bowl dry. Let us know what you find.

[Jason in TX]

distrib is most likely updated to modern upper plate, or electronic ignition.

[Chris Halsey]

All very good info! I dissconnected at the carb and it flowed okay, not a huge rush of fuel, but continuous. Did not know about the filter in the carb. Will have to check that next. Also the other suggestions you mention. Very helpful!! Thanks and I'll get right on it!

Chris

[Benson]

Originally Posted by Chris Halsey

All very good info! I dissconnected at the carb and it flowed okay, not a huge rush of fuel, but continuous. Did not know about the filter in the carb. Will have to check that next. Also the other suggestions you mention. Very helpful!! Thanks and I'll get right on it!

Chris

1. Did you open the GAV (dashboard adjustment) 3/4 to one turn? Close GAV clockwise GENTLY until if seats, then open 3/4 to 1 turn. THen start as engine warms close GAV down alittle to suit.

A cold Engine will not continue to run in cold weather with GAV closed.

Return GAV to 1/4 or so after warmed up.

[Tudortomnz]

Why not buy a reprint of the Handbook that came with every new Model A. Also a repair manual like Les Andrews. These Fords are not complicated, even I can keep mine running.

[flexiheep]

I had a similar symptom, ran for 30 seconds and then died, every single time..... I played with ignition and finally cleaned out the carb well and it ran just like it should. Reminded me that 90% of ignition problems are fuel related.

I thought it was electrical because it was so consistent in how long it ran, finally played with the choke and kept it running. Figured it was a plugged idle passage or something leaning out the mixture till it quit. The new gas gums things up quickly if they sit much.

[steve s]

The motor dying after a consistent short period of time is exactly what fuel restriction would look like; it's hard for me to imagine an electrical mechanism that would do that.

Did you try what Benson said?

Did you try advancing the throttle 3-5 notches before a cold start?

Can you keep it running by fiddling the throttle or choke rod?

Usually, engine dying reproducibly in a few minutes after startup is due to the gas cap is not venting; 30 seconds seems kind of short for that but it would be an easy check to try starting it without the gas cap on.

Usually a car will run for nearly a minute after you shut off the fuel valve. That's how long it takes to burn up the gas in the carb. THis is more in the ball park of your problem. Maybe the float valve in the carb is stuck, or maybe the fuel line is inserted so far into the carb that it's somehow severely restricting flow.

I don't know how long you ran your flow test for, but I'm a little concerned about your gas flow rate, although I don't think it's your immediate problem. It doesn't take much to idle, but to go down the road at a good clip you want a fuel stream that looks like a young man proudly writing his name in the snow, not an old man laboring to keep his shoes dry. If you just had a dribble, that could be the problem. Make sure that the fuel line isn't inserted too far into the sediment bowl.

Steve

[Chris Halsey]

All very good info.

So far,
Found the condenser, under the distributor cap. Still not sure how I missed that when I cleaned the points but then again, eyes don't work like they used to.

I too think it may be fuel related, as the gas tank had a lot of sediment in it when I bought the car. Had been sitting for years. I drained the tank and flushed with gallons of alcohol and "thought" I got most of it. I may not have. Fuel coming out at the carb is more "like an old man trying to keep his shoes dry" I have all the manuals, never leave home without them now, and have tried to start it just like the instructions tell me to. My wife's 28 starts and purs right off the bat, using the start up method listed in the instructions.
Anyway, my next try will be to see if maybe the fuel line is inserted too far into the sediment bowl. Never thought of that.....
If not, then I may have to remove the tank and get it boiled and sealed. When I replaced all the fuel lines, I inserted a new fuel filter at the tip leading into the tank. Was hoping that would prevent any crud from plugging up things....
Thanks again for all the info, and suggestions. Please keep them coming as they are all very good indeed!!!


Chris

[Chris H]

Hi Chris,

When I brought mine home two years ago I had a similar problem. It would run long enough to get me away from the house, then start back firing and finally die. It would restart after a few minutes, run for a few hundred feet and repeat the process all over again.

I found that the fuel flow out of the fuel line at the carb. bowl was as you found. The books I have say that it should produce a stream about the size of a pencil. The sediment bowl was clean. I just gave the fuel line a little shot of compressed air from a blow gun. Then I had the pencil sized stream. There was some rust/sediment that had found its way into the fuel shut-off valve where it enters the tank. I inserted one of those fuel strainers (available from most of the suppliers) into the fuel valve and eliminated the problem.

Another word of caution regarding off the shelf fuel filters, most are made for pressurized fuel systems and will not allow enough fuel flow from a gravity flow fuel system. If you are going to use one, make sure it is made for gravity flow fuel systems. The sediment bowl screen has provided enough protection for me.

Have fun with it.

Chris

[Special Coupe Frank]

Try running it with the cap off the gas tank... a plugged cap vent will allow fuel to flow for a brief while, then vacuum will build in the tank until it overcomes the pull off gravity on the fuel.