Ignition Issues, Crab distributor

[BIG KEV]

Here I am, I have been fighting a weird issue with my 34. It's a hopped up 59ab, rebuilt with 2k miles on it now roughly.

So I have had a weird issue, sitting and idling after its warmed up, it will bobble a bit, and start to feel off. Power is still great, no issues driving it but idle is the issue. Been through the carbs 10 times, I have swapped out to a new carb for testing, went down to 1 carb and still did the junk to me. Thought it was vapor lock, added a inline electric fuel pump and no resolve. I also changed from a 3 ohm internally regulated coil to a external regulated coil with a ballast resistor. New points replaced the stock 1942 set that was in there, I have had 10 condensers installed, cap, rotor, etc. I am running a nice set of Noble Speed solid core plug wires and NGK plugs

NGK B8HS10
Standard Coil UC12T
Standard Ballast resistor RU-13T

This made the issue less frequent, but engine temps over 180 she will do it. I can make her do it pretty easy now. Once she dies, sometimes she will restart sometimes not. A few days back I was stress testing her and she did it. Dies out and wouldn't restart. Tested spark, it was still blue but jumps about 1/8" instead of over a 1/4" It was doing. So I Jumped the ballast resistor, fired up instantly. This shows some of the issue, I know I could put the starter button with a diode and get 12v to the load side of the ballast resistor to fix this issue, but I am after the main issue plaguing me here of dying out.... The internal resisted coil made this restart issue, having to wait 2 to 5 min and it would restart. Coil has always gotten warm, even with the ballast resistor now it gets warm but not as hot as the internal resistor one did.

With this said, I've seen alot of people aiming for 3 ohms combined to keep the amperage down. Everyone says under 3.5 amps is key.

12.5volts, 3 ohms = 4.16 amps on paper, tested in real life = 4.25 amps

14.5 volts running at 3 ohms would be 4.83 amps.

Ohms law doesn't quite figure in thermal loss and resistance changes but still I am well into the 4 amp area.

I could go to a 2ohm coil with a 2 ohm ballast and cut my amperage down close to acceptable low 3 range to mid 3.

I know there are some stellar guys here who have fought the fight longer than I have. Just looking to get this car dependable again. It's done it in the cold weather but mostly does it in the 85 degree and above here.

Thanks in advance.

[koates]

Vacuum leak somewhere. Get yourself a vacuum gauge and connect into the intake manifold and read the chart that comes with the gauge. Regards, Kevin.

[Terry,OH]

I also suggest the vacuum gauge. Have you tried to remove the idle mixture screws and check the small passage is clear. Each screw should effect idle if one does not that is the one to check.

[BIG KEV]

Originally Posted by koates

Vacuum leak somewhere. Get yourself a vacuum gauge and connect into the intake manifold and read the chart that comes with the gauge. Regards, Kevin.

Originally Posted by Terry,OH

I also suggest the vacuum gauge. Have you tried to remove the idle mixture screws and check the small passage is clear. Each screw should effect idle if one does not that is the one to check.

Thanks guys.

I have thought the same. I did find one vacuum leak on my Sharp intake that I was using, pulled it off and put on my Offenhauser 2x2. The bad part about the vacuum port on these dual planes is its only getting signal from 4 cylinders of the motor. I have found this test to be a bit off at idle as well since the isky 1007b cam has a nice overlap. 12-15 at idle, Off idle I get 15 to 18, 1200 rpm I am over 20. Verified by my motorminder gauge inside.


Terry, I had both bases apart, full clean, rodded passages out, upper transition slot and lower with .030 welding wire, no obstructions. Every screw will do exactly what it should. Both carbs were synched with an airflow synch tool. The front base has a little more side to side play in the idle screws than the rear, but they sill seat just fine. Emulsion tubes have been replaced, carb tops were re surfaced, these Largo Logo Stromberg 97s have had the full gammet done to em.

I have the o-rings on all the intake valve guides when I built it, and 175 psi average compression across the board.

5 min of idling the coil will be warmed up while the block is still cold. I did a amp test running, I am averaging 3.2 amps running with current setup after 5 min. Voltage to the coil after ballast resistor is 7 volts running.

I am thinking these Standard T series coils may be the issue, I have heard alot of things lately on their quality being junk these days. I went ahead and ordered a Bosch 00012 to see how that goes. Fingers crossed!

[38 coupe]

I would use a coil marked for use with an external resistor when running an external resistor. Otherwise the combination will have too much resistance when everything gets hot.
Also, are you running the factory wiring? If yes, is the coil power wire still running through the resistor under the dash on the firewall?

[hueyhoolihan]

Sponsored Links (Register now to hide all advertisements)

i'm experiencing a similar problem, with my standard '41 setup. and have performed many of the tasks you have performed, trying and failing, to fix it. new distributor, points, condenser, plugs, wires, carb, fuel pump, etc., etc. starts readily, runs great at idle, and for about ten minutes out on the road at speed, and then begins the inevitable misfiring. progressing to the point, that i'm very, VERY relieved that i made it home without a calling a tow truck.

lately, i've been contemplating running a jumper directly from the battery to the coil in hopes of bypassing complications involving unwanted or possibly detrimental resistances. when i do it (and it could be a while, as i'm working on the parking brake system), i'll report my findings...

i'm not all that concerned about burning up the coil, as i have two new ones, that i assume are working properly, and a third that came with the car, that i have no real reason to think is not.

[Terry,OH]

hueyhoolihan: You have the classic signs of a bad ignition condenser or coil. If when cold OK and warm NG.
Consider a magneto condenser and have your original ford coil rebuilt by Skip Heney in Fla.

[BIG KEV]

Originally Posted by 38 coupe

I would use a coil marked for use with an external resistor when running an external resistor. Otherwise the combination will have too much resistance when everything gets hot.
Also, are you running the factory wiring? If yes, is the coil power wire still running through the resistor under the dash on the firewall?

Thanks 38.

The factory wiring was trash and the resistor was removed as it was damaged as well. So its path is through the fuse block then straight off ignition switch.

I put the bosch internally regulated coil on, fired up good and strong. I also checked the gaps on the plugs, they were a bit wide as well, .032 so tightened them up to spec .025. We will see how she does when I get a chance to take her out. I bypassed the ballast resistor when I installed the new coil since I didn't want to double resistance the circuit.

10 min run, normally the heads were as hot as the coil, this time, I could grab the coil and hold on to it. It was warm but not hot. First time ever!

I know larger gaps on plugs can make the ignition system work harder, that may have be a little contributing factor?

So we will see how she likes the changes. Fingers crossed!!!!

[BIG KEV]

Originally Posted by hueyhoolihan

i'm experiencing a similar problem, with my standard '41 setup. and have performed many of the tasks you have performed, trying and failing, to fix it. new distributor, points, condenser, plugs, wires, carb, fuel pump, etc., etc. starts readily, runs great at idle, and for about ten minutes out on the road at speed, and then begins the inevitable misfiring. progressing to the point, that i'm very, VERY relieved that i made it home without a calling a tow truck.

lately, i've been contemplating running a jumper directly from the battery to the coil in hopes of bypassing complications involving unwanted or possibly detrimental resistances. when i do it (and it could be a while, as i'm working on the parking brake system), i'll report my findings...

i'm not all that concerned about burning up the coil, as i have two new ones, that i assume are working properly, and a third that came with the car, that i have no real reason to think is not.

Yes this is a tell tale on a bad condenser. The breaking up says it all. Look for a good Echlin or NOS condenser. The little ones are just not holding up from all I have been finding. I have a 1942 Ford script condenser I carry as a spare that still works great!

[tubman]

Sounds like you may have a proper coil on it now. It would be interesting to know the amperage going through the points.

[GB SISSON]

After suffering through a series of bad condensors from napa on my crab in the woodie, I decided to switch to something I have used for 53 years without an ignition failure. My other hobby vehicles have been toyotas, land cruisers from the 60's in particular, but have had many daily driver totota pickups since 1971. Maybe some out there still think that Japanese stuff is junk, but they sure make good electrical parts. I have since been buying nos nippondenso condensors from late 60s-mid 70s. In fact I sent my last nos one to busmania along with the crab I sold him. Yesterday I received a package of 4 nos condensors for (if I remember correctly, a '71 corolla) I don't know what a microfarad is but these have 22 of them. I think that's about what we look for in our flathead fords. These were 11 bucks apiece with free shipping. 2 were in unopened boxes, other 2 clearly unused but no box. They come up often and I think this is a very good source for an inexpensive and highly reliable condensor.

[tubman]

As I have said before, the actual capacitance of a condenser is unimportant if it's within reason (.10 microfarads to .50). With modern coils, .22 microfarads are about perfect.

It's nice to know there may be a source of decent codensers out there.

[petehoovie]

Originally Posted by GB SISSON

After suffering through a series of bad condensors from napa on my crab in the woodie, I decided to switch to something I have used for 53 years without an ignition failure. My other hobby vehicles have been toyotas, land cruisers from the 60's in particular, but have had many daily driver totota pickups since 1971. Maybe some out there still think that Japanese stuff is junk, but they sure make good electrical parts. I have since been buying nos nippondenso condensors from late 60s-mid 70s. In fact I sent my last nos one to busmania along with the crab I sold him. Yesterday I received a package of 4 nos condensors for (if I remember correctly, a '71 corolla) I don't know what a microfarad is but these have 22 of them. I think that's about what we look for in our flathead fords. These were 11 bucks apiece with free shipping. 2 were in unopened boxes, other 2 clearly unused but no box. They come up often and I think this is a very good source for an inexpensive and highly reliable condensor.

[GB SISSON]

Thanks Pete! And let's not rule out that they very well may be available still from toyota. Never checked.

[BIG KEV]

Nice cool piece of info GB

Well, did my first stress test out in the wild today. 80 degrees this morning, did fine. Made it the 15 miles with no issues.

Driving home low 90s outside, motor never got over 170 degrees so the walker radiator is doing its job.

10 miles in, doing great, then I was coming to a stop, she died, thankfully had the foot on the clutch, so popped it and fired right back up like nothing happened. I pulled the choke ever so slightly to increase the idle speed a smidge, no more of this issue on the way home at all.

Turning in the neighborhood, downshifted to 1st to make the turn in, but never came to a stop, made the left turn and she started coughing like she was out of fuel, few seconds of breaking up and she came back to life and pulled like a raped ape.

I had one thought that was kinda disproven today, that the lower vacuum signal from a larger cam, makes the distributor brake do weird things, but I watched my moto minder inside the car, idle I have a fluctuating 15 roughly, and when these issues, she didn't really shown weird signs of vac issues, I have tested around carbs bases for leaks, intake gasket etc. NADA. One issue was under deceleration, and the other after deceleration and turning. Coincidence? who knows. I really don't want to drop a grand on new carbs but we may be at that point.

These 2 things she has never done before, but I have always found that increasing the idle speed seems to keep the dying out at bay. So, I am really thinking we are at a weird spot of carb issues or fuel delivery. May ditch the copper fuel lines from the mech pump to the carbs and go to rubber lines for heat soak issues. I'm pulling at straws right now. Off idle, midrange and top, she runs beautifully.

Maybe @unclemax can chime in?

[deuce_roadster]

I would be checking your float level or levels and fuel pressure. Do you have a good fuel filter?

[BIG KEV]

Float were set dry. Did a wet test on the car. 1/8” low on fuel level so maybe?

[hueyhoolihan]

if i had weights in my distributor that affected timing advance i might be focusing on whether or not they are responding immediately dramatic decreases in RPM. if they dont, ignition timing can be very inaccurate and cause unexpected stalling.

[BIG KEV]

Originally Posted by hueyhoolihan

if i had weights in my distributor that affected timing advance i might be focusing on whether or not they are responding immediately dramatic decreases in RPM. if they dont, ignition timing can be very inaccurate and cause unexpected stalling.

Thanks Huey, I have had it all apart, the weights are nice and free, gave them a drop of light oil when re assembled the distributor. But may be heat making things expand, who knows.

I did do a stress test today in the garage, 200 degrees with a Edelbrock 94 that came with an engine I had bought a while back. This is the brand new Holley 94 produced by Edelbrock. Pretty nice carb, insides look brand new. Put it on, took alot of adjustment to get it to idle. Idle is clean, get a little chop chop chop then lighter ,then more chop chop chop like normal. Heated it all up, no real issues at all. Shut it off, it was a little harder to restart but didn't have to touch the throttle and she fired off after about 5 rotations.

So maybe I need to buy a few new Strombergs or buying a new Big 97 and running a dummy out of all the parts I have here. This carb change shed some light on things. So real world test will follow probably this week.

[BIG KEV]

Originally Posted by hueyhoolihan

if i had weights in my distributor that affected timing advance i might be focusing on whether or not they are responding immediately dramatic decreases in RPM. if they dont, ignition timing can be very inaccurate and cause unexpected stalling.

Well, You hit something I think, did a second stress test today, started surging a bit, few hundred rpm, then started this light clattering from the front of the motor. Then it died, I did find when you block the vacuum to the distributor it dies.

Pulled the distributor off when it was HOT.

Curse words were said, but the advance was sticking when hot. once it cooled down the advance worked smooth like butter. I had a advance off another distributor here, so swapped that out, then I was looking at the vacuum brake, the piston fit a little loose in bore, you could rattle it side to side a couple thou. Checked the other housing I was scavenging from, NO play.

So I have cleaned, built another distributor out of some parts etc.

Wish Bubbas was still around, Id just send the distributor to him and let him do his voodoo magic to it. But maybe I have found something. FINGERS CROSSED>

Hope everyone had a good weekend!