Gurus help, please- Intermittent engine miss

[P.S.]

The Tudor was running like a swiss watch, just perfect. In fact, I became a little smug about how well it was running, even telling the wife the car is officially "cleared" for long trips now. A couple days ago, I installed a new fuel filter and re-adjusted the fairly new points from 0.17 to 0.21 as the tip of the point block finally wore a little. Also installed a new air maze air cleaner setup. Test drive, car ran great. The air maze actually made it a little quieter. Was very pleased.

Today, jumped in the Tudor to pick up some things from the store (about 8 mile round trip, all 2 lane country roads @ 35-45 MPH). On the way to town, the engine started to miss a beat every 10 seconds or so. Seemed to do it less when on the gas to accelerate. At idle, engine is smooth. Got to the store, got the necessary items and got in, Tudor almost didn't want to start, but eventually did. It did the "miss a beat" thing all the way home. Sometimes not for a minute or so, then would do it every 5 seconds now and then.

After getting home and letting the car cool off a bit, popped the dist cap and cleaned the points. Also pulled the plugs and cleaned them. Checked the timing, etc. All good. Reassembled everything. Went for a drive and the car started doing it again, but not quite as bad as it did on the way home from the store. Turned around and went back home. Thinking maybe the new air maze setup was causing a problem, took it off and went out again. Same thing. Possibly worse after the motor is good and warm than when it is cold. Came back home and turned on computer to ask you gurus what you think might be going on here?

The points and condenser have maybe 200 miles on them. Engine ran absolutely perfect before this morning. Nothing was changed from the last time it was driven 2 days ago running perfect, and now. Ideas, please?

[Tom Wesenberg]

Does the miss change if you move the spark lever a little up or down?
Does pulling the choke a little help or hinder?
Was the weather dry, damp, or wet?

[BRENT in 10-uh-C]

I will venture a guess that it is an intermittant short under the dist. plate.

[P.S.]

Miss didn't change with timing adjustment. Richened carb about half turn, no difference. Didn't try the choke because when it wasn't missing, it was running real strong. It just feels like one cylinder not firing at random with all 4 firing 99% of the time. Maybe best described as a random and far-between "stumble".

Using the modern points with wireless plate. Plugs had a little carbon around them, but looked pretty good. They are cleaned now, still doing it. Runs great when cold, begins to stumble randomly after warmed up.

Weather is dry and sunny. Temps in the upper 60's. Humidity 52%.

Could widening the point gap have led to this?

[Tom Wesenberg]

Set the points to .020" and have some lube on the rubbing block. Get rid of that wireless plate and you'll get rid of a common source of trouble. I only use original top plates and bottom plates with a very fine stranded wire.

I'd ditch the air cleaner also. You shouldn't have carbon buildup on the plugs. Maybe you need hotter plugs or a leaner mixture.

I assume it isn't an oil burner?

Repro ignition switches can also be a source of trouble. Make sure when it's in the ON position that the contacts make a firm contact. My repro switch would cut out as soon as I touched it and sometimes just from the weight of the small fob swinging back and forth. I made the contacts better and haven't had a problem since then. Also make sure the switch terminals aren't touching the gas tank.

It takes a little effort to make sure the ammeter terminals are clean and tight, as well as the terminal box terminals, so these two spots are often overlooked.

[Drive Shaft Dave]

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I would take a look at the wireless plate contact and the modern points insulator where the condenser and coil connect to.

[Drive Shaft Dave]

Tom beat me to it.

[P.S.]

Thanks, Tom.

It had carbon on the plugs even before adding the air filter. It does not burn oil, it usually runs great and real strong. Prior to today- ALWAYS starts right up and runs like a watch.

How do I lean out the high end? It has a Zenith carb. Rebuilt by the shop 2 months ago.

If I disconnect fuel line from the carb and turn the fuel on, it gushes out like a garden hose.

[P.S.]

Thanks Dave.

Points are only 3 months old. I did check the insulator, points, etc. today when inspecting the distributor. Also took a fine file to the points because I was desperate. The distributor was removed from the motor for a close inspection. Distributor was reinstalled on the car, timing checked, and the same thing happened.

Those solid state ignitions are looking better and better all the time....

[Ron Engen]

Try a new coil,preferably a flame thrower type.

[P.S.]

Tom-

See you edited your post. Here's more info pertinent to your added info:

The wiring is all tight and good. Soldered terminals on #12 or #10 authentic looking wire. Wires on the ammeter are tight. Ignition switch wires are tight, and there is insulation on the back to make sure they don't touch the tank (even though they aren't even close). However, it IS a repro ignition switch, and that is easy to swap out. Will try that. It's not a pop-out type. When it stumbles, the ammeter doesn't wiggle or anything. I would think if it was a wiring problem to the ammeter, it would wiggle when it made/broke contact, no? I made the last test-drive with the lights on, and all looked normal from an electrical perspective. Just a darned intermittent random motor stumble.

I did check the terminal box wiring a few days ago as part of a routine overall check. I found the passenger side nut about 1/4 turn loose and tightened both, then put the cover back on.

Thanks for the input, Ron. I don't have a spare coil around, but perhaps it's time I did.

[Tom Wesenberg]

Try turning in the GAV until it's as lean as can be without a stumble. I run with mine closed except for the first 30 seconds or so after a cold start. My plugs stay nice and clean.

Maybe you need a hotter plug.

[P.S.]

Like you, I always run the GAV completely closed (fully CW) after about 30 seconds or so on a cold startup.. When it's warm outside, I don't open the GAV at all. However, my plugs get some carbon around the outside and on the anode. The center electrode still looks good though.

[pat in Santa Cruz]

those wireless plates have been known as troublesome since they appeared on the scene, at least for 30 years. It might be something else, but its the first red flag I read in your post. It sounds like bad contact somewhere, but the possibilities for exactly where are many. Let us know when you get it so we can learn something.

[[email protected]]

I recall two cases like yours.

One was a Model A with the safety fuse mounted on the starter. He had a loose wire on one of the terminals that caused his problems. Also I reported before from my own experience that the glass tube fuses have to be checked with a meter as the China made ones may look good but some don't conduct electricity.

The other was a condenser that the mounting tab had broken away from the spot welds holdng it on to the can. It looked OK but if you pushed on the tab with a screwdriver it would run better. Also if your disti has been painted check that it still makes good ground connections going into the head and where the condenser is attached.

Good luck and remember the fix is often the last thing you try. Or the problem was caused by the last thing you tried....

[Logan]

Take your wireless plate out of the distributor turn around and throw it as far as you can. They are worthless pieces of junk. Order a new set up with the wire and that will solve your problem. I never could get a wireless plate to work worth a damn. And it had the same symptoms you describe. And as far as your comment on solid state ignitions, I highly recommend them. In my experiences they work really really well.

[TK in LA]

Just as a shot in the dark, did you try changing the plugs out. I've had an occasion that the plugs looked good but intermittently miss fired. Replacing them cured the problem. Just a thought. Good luck!

[newshirt]

I had the same problem a few months ago after changing the distributor points block. I suspected that the points were occasionally touching the block. (See photo.) I filed the edge of the points block and it never happened again.

[P.S.]

Wow! Thank you all for the excellent input and expertise! Especially Tom's and Logan's, ha ha!

Taking all the expert advice and combining that with my own loss of patience for this- Decided the best way to "chase" this was to not chase it at all and just "shotgun" it and replace the entire ignition system with a stock type setup like Tom advised. Called Bratton's this morning and ordered their complete new distributor with stock points, a new coil, new ignition switch, and all new wiring.

Due to my line of work, I have no patience for temperamental devices or fragile equipment. I refuse to go through this every 4 weeks or so when the car will just act up for no good reason. Decided a complete "do over" is the only way I am ever going to rid this car of these ignition system gremlins.

I thought these cars were supposed to be super reliable??? Mine is always giving me fits!

[Louis]

Originally Posted by P.S.

Wow! Thank you all for the excellent input and expertise! Especially Tom's and Logan's, ha ha!

Taking all the expert advice and combining that with my own loss of patience for this- Decided the best way to "chase" this was to not chase it at all and just "shotgun" it and replace the entire ignition system with a stock type setup like Tom advised. Called Bratton's this morning and ordered their complete new distributor with stock points, a new coil, new ignition switch, and all new wiring.

Due to my line of work, I have no patience for temperamental devices or fragile equipment. I refuse to go through this every 4 weeks or so when the car will just act up for no good reason. Decided a complete "do over" is the only way I am ever going to rid this car of these ignition system gremlins.

I thought these cars were supposed to be super reliable??? Mine is always giving me fits!

Could it be that nothing is wrong with the car ?... maybe another problem... .
Good luck.

[BILL WILLIAMSON]

P.S,
Check for arcing in the dark. On Minerva, spark going to # 4 would arc through the top of the cap to # 3 plug strap. Look for FUZZY black area on top of the shiny cap surface. Bill W.

[P.S.]

Louis- Like what?? Suggestions, please.

Roger that, Bill. Checked for that. Thanks!!!

The gremlins will not win this time. We WILL get this thing running correctly!! Or the checkbook will die trying...

[[email protected]]

We are all assuming that you have being running with good gasoline and you didn't pick up a tank of crappy gas. Too much alcohol, or water got into your gas. If you get a lot of water in the gas tank the sediment bulb usually will show it with a gas / water separation line unless it is a lot... Sometimes all of the problems go away with a fresh tank of gas... We have seen guys take off the sediment bulb and the stuff in there would not even light with a match.

[Fred K-OR]

Bill may be on to something talking about the distributor top stuff. I had a problem like this but it was due to my incompetence in that I forgot to hook up a couple of spark plug wires to the distributor. So they were just touching and arcing from the distributor to the plug most of the time but would miss. So guess my point is that maybe there is something arcing up in the top part of the distributor like Bill suggests.

[Marco Tahtaras]

Originally Posted by P.S.

Decided the best way to "chase" this was to not chase it at all and just "shotgun" it and replace the entire ignition system with a stock type setup like Tom advised. Called Bratton's this morning and ordered their complete new distributor with stock points, a new coil, new ignition switch, and all new wiring.

I strongly recommend that you change one thing at at time and see what pans out. If you never single out the source of the problem how will you ever have confidence in the car? I too am betting on the distributor arcing below the upper plate. With that said I can't disregard the bad gas suggestion depending on how it fits in your timeline of the problem appearing.

I thought these cars were supposed to be super reliable??? Mine is always giving me fits!

The biggest weakness in the Model A is human error. It generally begins long before we acquire them but it requires someone along the line to reverse the trend.

[P.S.]

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Continued good input, thanks again.

It's the same tank of fuel as when it was running perfect. I only use Chevron fuel (it's the only consistent brand out this way). I mix a little MMO in the fuel at each fillup. The tank is now between 1/2 and 3/4 full, and it gets topped off at each fillup, so it ran for over 30 miles perfectly on that tank, then started acting up just yesterday morning.

Fred- Does the same thing with the older cap on it. And, I did check to make sure there was no arcing between any strap and anything else after taking the plugs out and cleaning them. I remember having that same problem once a long time ago, and bougt another new cap because of it. This is a similar symptom, but likely a different cause.

Marco- I respect your opinion. Perhaps I'll start with the distributor and use the same wiring and coil just to satisfy our curiosity. As you mentioned, confidence in the car is the issue. That's why I just wanted to shotgun the whole electrical system. The goal is to get a reliable car, not one that is always questionable from day to day. That is unacceptable.

Louis- Unlike most people here, this isn't my hobby or toy. We rely on this car for transportation. It has to be reliable and dependable. If it isn't, I will have a very difficult time justifying keeping it. I let go of a 69 Charger to get the Model A, and don't need any more "told you so" sarcasm out of my family. We use our car, we don't "play" with it. That makes these intermittent problems much more important to solve and move on quickly, and not spend weeks fiddling with it. Does that help explain the "shotgun it" method of procedure?

[Louis]

P.S.
What I meant about the problem not being the car, was that the problem may be you, and I'm not trying to be a wise ass,
In your org. post you said it was running just great [sweet], then you start telling us how many things you changed or added to the car [ shotgun it ].
I agree with Marco, if you have a problem you just don't start throwing parts at it or you will never know where to look if the problem comes up agin, all of the parts that you are talking about don't go bad all at the same time, A lot of good advice above from people who know A models, you should take it instead of your [shotgun method]
I really do wish you good luck.
from all that you have said I would guess the problem is in the dist.
All of this is just my opinion.

An 82 year old car is a hobby, not for everyday transport. A stock mode A is not up to todays roads or to blend in with todays modern cars.

[James Rogers]

I can't believe nobody has suggested removing the air maze and see how it runs. Seems to me like this was the only real change before the car started acting up.

[Tom Wesenberg]

Originally Posted by James Rogers

I can't believe nobody has suggested removing the air maze and see how it runs. Seems to me like this was the only real change before the car started acting up.

Someone did back in post #5

[P.S.]

Oh, the air maze issue was also discussed in the original post.

I am going to take Tom and Marco's advice.

Tom's advice for going to the stock distributor setup, and Marco's advice for swapping one thing at a time. You guys are great. Thank you so much!

[steve s]

Originally Posted by P.S.

... A couple days ago, I installed a new fuel filter and re-adjusted the fairly new points from 0.17 to 0.21 as the tip of the point block finally wore a little. Also installed a new air maze air cleaner setup. ...

So far, all of the opining has been on the points and air cleaner; why not consider the fuel filter? I have seen them cause a lot of problems for a lot of people, sometimes intermittently. The fact that the problem occurs after warmup suggests fuel vaporization to me. I've watched with my own eyes fuel filters plug up with a bubble of vapor, sometimes shutting down the motor, sometimes causing a hiccup, and sometimes having no apparent effect. It might not be the filter per se that changed, but something about how the fuel line was connected providing a locus for vapor bubble trapping. Again, I am NOT questioning that you have good fuel flow parked in the driveway.

Steve

[Fred K-OR]

I notice Ron mentioned back a ways, to try a new coil. I don't remenber if you said you did that or not. The reason I brought this up is that I had a problem where my rig would just quit like I turned the key off. This would happen after it warmed up. Then I would try to start it, and most times it would start right up. If I remember, I think Tom W mentioned that it could be the coil. I put another coil on and since then I have not had any more problems in this area. Just a thought.

[P.S.]

Thanks, Steve. Easy enough to do. It's worth a try. Although, the car ran very well with the filter inline before yesterday. I'll put that idea in the hopper just in case.

Thanks, Fred. I haven't changed the coil, but it is one of the things I ordered for this and plan to change it as step #2 right behind changing the distributor.

You guys have been very helpful and generous. Thanks!

[dave in australia]

At a long stretch, could it be some grunge in one of the jets. I have a long story about a lizard and a petrol tank. To make it short though, once the petrified lizard was removed, the intermittent fuel flow problem went away.

[Dave in Boise]

I vote for weak condensor.. Mine would act up on me only when it started to get good and warm, and then finally died.. it was as reported.. runs strong when cool, and as it warmed up, intermittent missing and lower power..

Good luck and let us know if you discover your gremlin

- Dave in Boise

[Kevin in NJ]

Something to understand.

You do not need to change points or condenser until they are problems.

I know this is contrary to what seems to be common knowledge, but the changing points regularly come from the old days. The cars were driven everyday and they would wear out and the shops made money from talking you into frequent changes. Regularly replacing the points in your A is a waste of money and will cause you to have to reset the points often. A new set of points will wear more rapidly as they wear into the cam. You should expect the time between needing re-adjustment to extend after each setting as the wear block start fitting the properly lubricated smooth cam.

I think today there is a psychological need to do something to maintain the car and points are easy to do. So many guys needlessly fool with them and cause more problems. A properly restored A really just needs to be kept properly lubricated to be happy for many years. No hydraulic brakes to fail, just keep gas in it and drive.

The points need to be changed only when the wear block is worn out or the points have issues. If the point contacts have some kind of problems then you need to consider if you have a failing condenser or other electrical problem. Also low quality points tend to fail faster. You also need to know that the stationary block can be adjusted so you get the point contacts fully contacting. You need to loosen the screws under the plate.

You also need to look at and feel your distributor cam. It should be smooth. You also want to check that the point gap is the same for each lobe.

Now you also need to be aware of some realities. There are good points and bad points. Some the wear blocks will wear quick and others the point metal is a low quality. The burnout proof condensers that are sold today have a great reputation for not failing. I have noticed in my pile of old used points that some have contact points to be like new and others are coated in a white oxide. Interesting, all the old Ford script points have nice new looking contact points and decent wear blocks. The none Ford points varied with the Blue points looking nice. The NORS cheapy points I have still on their cardboard holder from the 40's have contact points that have a layer of white oxide on them. My take is spend the money no NOS Ford points in the old box and a new good repro or NOS B ignition cam and you are likely to never need to change the points for several generations of family ownership. Or put on a good used set of script points and expect them to last 30 or 40 years. Keep in mind my brothers cars has the same used aftermarket points that came with the car. He has been running the car since 1970.

A side comment on the modern condenser. I was reading on a Mustang forum that the new condensers are hit or miss on quality. It seems that the new ones are being sourced by lowest bidder and they may not have the best quality. So you could get the FoMoCo brand condenser and one week get a great one and the next week get one that fails in a few months.
I believe that the burnout proof original style condensers are probably sourced with better quality condensers and you are likely to get very high quality control. I believe A&L is making all the condensers and they tend to do only high quality parts.

[P.S.]

Hi Dave and gang,

Figured it would be a sign of true thankfulness for your help if I posted an update.

Received the new distributor from Bratton's and went to work polishing the points cam, adjusting and lubing, etc. Installed in car, and went for a drive earlier today. WOW, the car runs like a watch again! What a difference. Also noticed that the motor runs stronger now with the old style points than it ever did with the "modern" points setup. I especially love how simple it is to adjust and clean the old style points. Why did people start using the "modern" points at all??

Special THANK YOU to Tom for steering me toward the original style points. What a difference, you were right!

And for those who scoffed at my desire for perfection, why did you even bother posting? If you're not part of the solution... You know the rest.