How Do Bad Coils Act?

[grey beard]

Well, Gentlemen, I have found and fixed the problem - I think. My face is a litle red, my tail is tucked firmly between me legs, and I am appropriately contrite.

Almost missed it. Pulled the carb off this morning and pulled it apart after dinner, this evening. Completely disassembled the critter, even pulled a few of the soft plugs, blew shop air and Brakeclean hrough every passage. Everything was fine. When I put the float back in and adjusted it, I found it to be low compared to shop manual specs, and fixed that.

Last piece into the innards was the little flat metal "C" shaped spring that retains the float pivot pin. Wouldn't you know it but that little devil was deformed just enough that when I slipped it in its slot, one end went down behing the vertical tang on the float arm that is supposed to hit the needle valve. This piece was actually holding the float up against the needle valve, and effectively shutting nearly all the fuel off from the bowl. Apparanly enough gas was entering to allow it to start and idle, but not enough volume to let it accelerate.

Guess I'll know for sure tomorfrow whan I reinstall the carb. Sure hope this fixes the problem.

[MBF]

Nice going GB! Its usually something very simple that is the root cause, but it'll drive you crazy while trying to find it. The Carter BBD uses a similar float pivot restraint-great design right! Hope that does the trick for ya. Mike

[grey beard]

My high speed stumble/miss issue is fixed. For the first time since the engine was overhauled, it runs full throttle and accelerates nice and strongly. Here’s how I found the culprit.

My buddy, Frank, is a retired Verizon lineman. He’s not a real engine head, but does understand electricity. After he helped me reinstall the carb and we discovered the same problem was present, we discussed it and he told me how he had found bad plug wires using an inductive timing light to move the clamp around and find bad spots.

With that thought in mind, I fished out my own inductive timing light and clamped the secondary coil lead – sorta’ like a poor man’s scope. Watching the timing light and accelerating to higher rpm, I discovered that as soon as the miss kicked in – about 2500 rpm – the light began to flicker and bounce, as opposed to steady firing at lower speeds. This proved to me that the problem was really ignition related.

Pulled the distributor yet again – comes out real easy after half a dozen trips in and out – and found that the breaker plate bearing had separated from the base – the two parts of the plate, movable and fixed, were coming apart. Did you’all know that if someone installs a contact point retainer screw that is too long, it pushes the two pieces of the breaker plate apart? Well, this may have been what caused this problem/.

Anyhow, while fixing this issue, I found that the breaker point spring was very light and puny, hardly enough tension to keep the points from bouncing. Looked at the original points I had taken out and saved, and they had two springs – steel and copper – together, while my new set had just a very light copper spring. Put the old contact set in and – Bob’s Your Uncle – she fired right up and ran like a scalded dog.

The defective point set came from NAPA - Echlin - and is their part #CS725A. I’m going to get a new set to keep in inventory, but I won’t be getting another one of this type, for sure. This miserable problem has cost me nearly six full days of head scratchin’ work and frustration. Glad it’s fixed.

I suppose the moral of this sad story is that you can never safely assume that just because a new part was installed, that it isn’t still the culprit. Go figure . . . . . .

[Merle Coggins]

I am currently having a similar problem to what Dave had, so I went searching for this thread and revived it.

My truck ran great, but I knew that the cheap Andy Bernbaum points that I had were going to need to be replaced soon. I was running out of adjustment because the cheap nylon rubbing block would wear too fast. So I ordered up a complete set of tune up parts from Napa, including an extra set of points. My plan was to replace the points and keep the rest of the parts on hand as a "spare tune up kit".

So last weekend I pulled out the distributor and commenced to replacing the points. The Echlin points from Napa looked much beefier and better built than the cheap ones that I had. When I was replacing them I noticed that the wire from the condenser had a rub mark through the insulation. Apparently it was chaffing against something in the distributor. So I also replaced the condensor with my new Napa one. Then when I was setting the dwell, like an idiot, I left the rotor in place. I had set it back on to reference which way it was pointing when I installed the dist. However, when you're cranking the engine over, watching the dwell meter, and adjusting the points with a screwdriver, the rotor must be removed. I realized this when it came around an wacked my screwdriver and knocked it out of my hand. In the process the rotor broke. So, now I also have my new Napa rotor in there too.

I didn't get a chance to go for a test ride at that time but the engine ran great. Then during the week I installed my new electric fuel pump in line between the tank and mechanical pump. This pump is to help refill the carb after it sits for a while. Again all went well and everything appears to be working fine.

Now this morning I decide to drive the Ol' Dodge to work for a test drive before my Dayton, OH trip next week. NOW I HAVE AN ISSUE! The truck won't go over 55 MPH. When I reach that speed (RPM) it acts like I have a rev limiter installed. It will stutter and stop pulling. I first suspected the electric fuel pump was restricting the gas flow so I reached down and flipped on the switch to get it running to. NO CHANGE. I also tried pulling out the choke to see if it was a lean running issue (like running out of gas). Again NO CHANGE. I believe something happened during the "tune up". I have another new condenser and rotor to replace the ones I used. I guess I'll have to get in there and check everything over again. I'll also check the breaker plate as stated in Dave's final fix post.

Any ideas how to check a condenser to know if it's bad? Maybe I can dig out my old one and try it again. Everything was working just fine before the "tune up". ARRGGG!!!

Merle

[Dave72dt]

Go back and set the points with a feeler gauge. A worn dist shaft can give you false dwell readings and won't let the engine run properly. I've found a "correct gap" more effective than correct dwell. If you can get both, that's great but often as not , that doesn't happen.

[Merle Coggins]

Well, I pulled it into the shop after everyone left for the day. If I revved it up it would get to a point where it wouldn't rev any more. It would stutter and bog down. I replaced the condenser with the other new one I had, no change. I rechecked the points gap, no change. I guess I'll have to pull out the distributor this weekend, at home, and give it a thorough going through.

It's gotta be running good by Monday afternoon or I'll have to take my '06 Ford to the Chrysler Meet.

Merle

[lugnut123]

your carb should have a vaccum port in it's base. If you don't havee the right base gasket your moter mite run bad . just thinking out loud. good luck

[grey beard]

Merle,

Since my last posts on this issue - more than a year ago - I have suffered through another sorta' identical issue to what you described. The motor accelerated well and started and idles just fine, hut at a steady medium throttle speed it broke up and hucked a lot on the road in high gear at cruise speed. Accelerated just fine but would not run smoothly at medium throttle.

My air cleaner it the large variety with a hrace that runs across the head to the drivers' side of the head. I had the carb off three times and finally ran it withj the air cleaner off - ran better. When I installed the air cleaner it broke up on cruise.

Pulled the carh off again - those screws come out real easy afrter about a dozen trip apart and gack together. Anyhow, a close inspection revealed the wrong - read too big - gaskets on the carb aluminum spacer between the base and the main body. These taskets came in a new kit I boughr at great price - just installed 'em and figured they were correct. WRONG! Gasklets were tpp hig at the hole. New gaskets rixed the cruise problem. Now it runs and cruises jsut fine.

[greg g]

Young Ed just posted the same gasket concerns on the car side. with similar symptoms. Stumbling at midrange. Apparently the off shore folks who are making the kits these days have a casual disregaurd for proper specifications.

[grey beard]

Yup, lesson learned is that one can never safely assume a new part is going to work properly. In my case, the gaskets were almost right - and as Greg mentioned, they probably originated in the "land of aomost-right." *Asia)

Of course, once they began leakkng air into the intake system, it ran lean and stumbled around while on the main metering circuit. On acceleration, the power valve overcame this small air leak and it pulled okay. It was just on steady throttle cruise speeds above idle where the problem reared its ugly head.

I have learned to look carburetor parts over more carefully, and will never again assume that the kit parts I buy will be an exact fit. Fortunately for me, in this case I had extra gaskets I had saved from previous carb overhauls that I was able to scrounge up and use.

Now this old Dodge is a pleasure to drive. Can't wait to get the new transmission installed and have a working synchronizer once again . . .

Good Luck

[Merle Coggins]

I"m back in business. Ever have one of those moments when you just need to slap yourself in the head? Here's the long winded scenario of my Saturday morning.

So, Friday evening I got to thinking, "What's the one piece I didn't change?". So my first step was to replace the cap. NO CHANGE. I noticed that the rotor fits loosely on the shaft, but since the original one broke I had to run with it, but suspected it may be an issue.

My next step was to pull the distributor out, clamped it in the soft jaws of my vice, and gave it a thorough inspection. I couldn't find anything wrong so I lubed things up, reassembled it, reset the points, and reinstalled it. NO CHANGE. After I reset the timing I tried the trick that Dave mentioned above. When I reved it up I found that at the point where it dogs out the timing retards again and the light doesn't flash the same way.

I dug out the condenser that was in there before the "tune-up" and put it back in. Even though I had tried 2 different new condensers I had to try something. NO CHANGE. But during the next test run I had my dwell meter hooked up and found that as the RPM went up the dwell reading went down. At the point of rough running the dwell was down around 10. Now I'm suspecting points bounce.

I then decided to pull the distributor out of the spare engine I have out of my parts truck and install that one in my truck. I cleaned it up, checked the points gap, and dropped it in. It fired up and reved perfectly. NO MORE PROBLEM. Right about then my neighbor came out to chat. I left it idleing while I was talking with him. During our chat the engine died and wouldn't restart. "WHAT THE @#%$^&". After much fiddleing I finally found that I had pinched the little wire, that goes to the points, under the cap and it had shorted out to the case. DOHH!!. During all the messing with this other distributor I noticed that the points had MUCH more spring tension than my mew points have. So, I was going to pull the points out of this dizzy and put them in the other one. During the removal of these points is when I had the "DUH, I'm an Idiot" moment.

The new points have a copper spring strap and also came with another spring strap loose in the box. I slipped the additional spring around the outside of the copper strap when I installed the points, but it didn't seem to do much. Since the points that I had in there before only had a single spring/connection strap I had no reference on how it should have been assembled. The "extra" spring fit no nicely around the outside I didn't think about finding another way to install it.

When I was removing the points from the parts truck dizzy I realized that the extra spring should be INSIDE of the copper strap. I grabbed the new points again and sure enough, it locks right in there and adds the proper spring tension needed. I reinstalled the, properly assembled, new points again and reinstalled my dizzy with the new condenser again. It now runs good again. I can pull it up to 40 MPH in 3rd gear (could barely get 30 before) and it now continues to pull up to 70 MPH (that's where I quit). Good to go now.

It's amazing how things work when everything is assembled correctly. Now I feel comfortable about driving it to Dayton this week.

Merle

[grey beard]

Merle,

Had exactly the same experience - new points from NAPA that lacked the steel spring in the box. Never noticed it till I hit the same snag as you did. Second spring sure helps with the higher rpm.

Sometimes it's hard to know if a problem is fuel or ignition-related. One thing Iearned when diagnosing engine drivablilty problems with these engines - hook a timing light to the engine and watch it flash. If it changes with rpm, you know you have an ignition problem - simple as that. It's a good diagnostic tool and easy to hook up.

I also found another neat tool for diagnosis - Waekon Arc KV Probe. A little pistol grip with a digital KV voltage scale in the handle. Just hook it around any secondary ignition wire and a bright led light flashes with the spark. Gives the voltage reading digitally, and when you disconneft it from the wire, a light comes on - red or green - to show you if your coil polarity is right or wrong. Costs like sixty nine bukzz at tooltopia.com. A neat little diagnostic tool I learned about whilst sitting at the feet of the master, himself - Dean Coatney.

Thanks, Don

[Don Coatney]

How do bad coils act????

Nobody has said it so I guess I will.

Bad coils do not behave as they should. They talk back through the carburetor and exhaust, skip when they should be in attendence, do not work when they should, cannot be relied upon, frequently cause trouble, take a leak in areas where they should not, will frequently snap back, does not help to condense them, they refuse to work in hot weather, sometimes they refuse to work in cold weather, sometimes they refuse to work in nice weather, they can and will disrupt normal activities, if you physically dicipline them they will stop altoghether.

That is a few ways that coils gone bad act.

[Dave72dt]

The Echlin point sets also used to come with a small capsule of cam lube and a small slip of paper with a diagram showing the location of the steel spring. Those probably didn't show up in the box either.

[Merle Coggins]

The Echlin point sets also used to come with a small capsule of cam lube and a small slip of paper with a diagram showing the location of the steel spring. Those probably didn't show up in the box either.

Yes, they were in the boxs of both sets I got.

I also found another neat tool for diagnosis - Waekon Arc KV Probe. A little pistol grip with a digital KV voltage scale in the handle. Just hook it around any secondary ignition wire and a bright led light flashes with the spark. Gives the voltage reading digitally, and when you disconneft it from the wire, a light comes on - red or green - to show you if your coil polarity is right or wrong. Costs like sixty nine bukzz at tooltopia.com. A neat little diagnostic tool I learned about whilst sitting at the feet of the master, himself - Dean Coatney.

Thanks, Don

I saw that tool on Tooltopia and thought about getting one, but I wondered how often I would use it and decided not to get it. Maybe some day I'll get one anyway.

Merle

[Fernando Mendes]

I already had ignition problem with my Jeep last year.I checked all this points, except the condenser.Talking with a friend he said to me "look out for condenser",it is more important!!!Begin replacing the condenser.After the rest.

[Dave72dt]

Yes, they were in the boxs of both sets I got.

I saw that tool on Tooltopia and thought about getting one, but I wondered how often I would use it and decided not to get it. Maybe some day I'll get one anyway.

Merle

I think long and hard about diagnostic tools, especially on these old vehicles. A test light, VOM, dwell-tach meter and timing light will get you a long way down the road with these basic engines. A timing light can test secondary wires well enough to know if they are working or not. Checking them at night or in a dark area will check for leakage or jumping and I can visually check polarity

[John-T-53]

I just got my newly rebuilt (for the 2nd time) engine running last week again, and have been tuning it hard core over the past few days.

It's running strong and drives great at all rpm's. Initially, it was a lil' rough running and had throttle problems, but the carburetors have been tinkered with several times and the setup is now synced up pretty good.

The slight miss was still there though. A timing light showed the miss on the pulley mark as it would skip a beat about every ten flashes. I was running an original auto lite coil, but had a new spare on hand so I switched 'em.

Now, a consistent flash on #1, however the mark moves around slightly, about two deg when running. BUT...at least this showed the old coil "skipping when it should be in attendance".

If I put the timing light inductor on the #6 wire, the timing is advanced about 4 degrees that that of #1, and there still a very slight miss evident in the tail pipe at idle. The dizzy has never been rebuilt, although points and coil have been maintained. The dwell is 39 deg at idle and moves down about 5 deg when accelerated. It might be time for a new dizzy, possibly a pertronix unit... Does this now sound like a dizzy problem?

[HanksB3B]

Hi John,

I'd definitely carefully examine the wires inside the distributor, there could be a short. I have a good diagnostics guy (far from you) but if you can find a good mechanic up your way that is up to par with diagnostic machines with a first love for 50's vehicles, he may be able to see things the naked eye can't.

As far as your newly rebuilt engine goes "Long may you run"

Hank

Edited January 6, 2013 by HanksB3B

[Jeff Balazs]

Hi John;

It could be some play in the distributor itself but have you tried a different cap and rotor combination? I have run into very similar problems in the past which ended up being poorly made replacement parts. In the case of a certain model Delco distributor I found I had to fit OEM replacements manufactured by Delco......the others fit and looked the same but just didn't work nearly as well.

Hope this helps.

Jeff

[JBNeal]

A rebuilt engine will respond to optimum performance levels with a healthy ignition system and adequate fuel delivery. A faulty distributor can be repaired by a competent technician who is able to check all the variables in distributor performance. Distributors are prone to worn & out-of-adjustment points, condensor blow-outs, frozen or worn breaker plates, leaky vacuum advances, worn or out-of-balance mechanical advances, input shaft bearing wear, internal short circuits...I believe there are shop manuals that deal with the distributor/ignition coil combination alone because there are technical aspects that have to be addressed systematically to achieve proper function. The repair shops that advertise that they use a Sun Testing Machine to diagnose distributor issues get my attention as these pieces of equipment were used by mechanics back in the day to restore ignition performance. As distributors went to solid state components, these testing machines and the skill to use them became obsolete. Finding a shop that still has them and knows how to use them is an asset in owning a vintage beast

[DJ194950]

No amount of (tune-up) will cure worn dist. bushings.

Dwell will ideally not change with rpm change.

Quick and easy dist. bushing check- remove cap. Push on the shaft side to side, point opening change = worn dist. bushings. Change of dwell will change the time coil has to soak up spark, also will change timing.

Just my 2 cents.

Doug

[Don Coatney]

The repair shops that advertise that they use a Sun Testing Machine to diagnose distributor issues get my attention as these pieces of equipment were used by mechanics back in the day to restore ignition performance.

By using a power supply, electric drill motor, dwell meter, and a vacuum generator you can replicate all the functions of the Sun Distributor machine.

[HanksB3B]

^^^Don, you never cease to amaze me^^^

Also (don't know who wrote it) found this in my distributor folder.

Distributor Rebuild

If you remove the points, condenser, and vacuum advance (pay attention to how it goes back together) you can then remove a couple of screws around the outside that hold the breaker plate in place. The breaker plate will then lift out and you'll have access to the advance weights. I wouldn't recommend disassembling any more than that. At this point you can clean things with solvent of brake clean as needed. Once it's all clean and dry drip a little oil at the pivot points on the advance weights and reassemble the rest. That's what I did with mine and it works fine.

That vacuum advance arm is that supposed to be a clip on the end holding it on the stud on the plate? Mine looks like a fine wire wrapped around the post. I'm gonna loose that I bet..

Yes, its a little wire clip. Be very careful when you remove it so that it doesn't go flying or you'll never see it again.

Distributor Position

Verified that the distributor is not 180' off by rotating the engine with my finger over the #1 spark plug hole until I could feel the compression stroke. Also double checked the placement and sequence of the spark plug cables in the distributor cap.

I mark the location of the rotor and also the location of the body of the distributor to a specific point on the block. I mark with a piece of chalk for the dizzy and also a piece of black tape (also the same for the rotor).

Disconnect the wire from the coil and also the vacuum advance line. Loosen the bolt that hold the distributor and pull the unit up and out of the block.

When you bench test for the gapping, set the rotor to the correct marking and then install the distributor and align it up to the mark you made on the block. Tighten the bolt a little but not fully. Start the car and then use the timing light to adjust the timing to the timing mark on the lower pulley. You can use a 12volt timing light,(just reverse the leads). The light will be a little weaker so do the timing when the lights are off in the garage so you can see the timing mark. Move the distributor either right or left to advance or retard the timing until you get the timing light firing when the timing mark aligns with the pointer on the block.

I always like to install a new breaker plate assembly since everything is then already connected. Keep your old plate and then rebuild with the new internal parts. Grease the small ball bearing the make the two plates rotate

 

The fastener at 7 o’clock id the distributor hold down as well as the timing adjustment clamp. Removing that screw will allow the dist to be pulled out of the engine assuming the wire and vacuum advance have been removed. You don't need to align the engine to tdc number one to pull the dist. just mark the location of the vacuum advance to the block and the rotor position. As long as you do not rotate the engine with e dist out, you will not have a problem reinserting the dist. The dist is driven by the oil pump, with a tang onthe ed of the shaft that look like a screw driver. I will go in either correctly or 180 off. so even if you do crank the engine you still have a 50/0 chance of getting it correct when going back in.

It is actually much easier to service the distributor with it out of the block.

The bare wire that you show, as long as it is not contacting any other metal parts in the dist should be OK. There were three of four (maybe more) different distributors used on MOPAR flat 6 engine. Assuming you have a 23 inch long engine, they all interchange. However their parts do not. There is a metal tag on the dist with a number on it. The replacement parts should be ordered by referencing that number.

With the dist out, you can check the unit for wear, clean it up lubricae it and replace the points and adjust them much easier than when in the vehicle. It will also keep you from dropping and loosing the small screws down into the body of the dist.

So take a piece of chalk or tire crayon and mark the vacuum chambers position to the block and the rotors position to the edge of the body and pull it out and give it a good inspection, cleaning and new set of tune up parts (rotor cap, points and condenser). Examine the shaft to see how much wiggle you have in the bushings. You can also check the vacuum advance to make sure the diaphragm holds vacuum. either by sucking on it out using a vacuum pump to assure it holds vacuum and moves the breaker plate smoothly.

Hank

Edited January 7, 2013 by HanksB3B

[John-T-53]

Confirmed...the shaft is a little loose in the distrubutor body, and I witnessed the point gap move as the shaft was rocked side to side.

Anybody ever rebuild their dizzy with new bushings? I couldn't find any threads where this was covered in detail (as you know I like to revive old threads)...however sending it out to a shop that rebuilds them has been discussed.

I'd at least like to find where new bushings could be sourced. After pressing them in, I'd imagine they would need to be honed to fit the shaft perfectly, probably with less than half thou' clearance.

Thanks,