Technical 54 WCFB woes and my incompetence

Okay folks you know the story….
WCFB model 2041S falls flat when using and More than the first 2/3rds of the primary throttle blades.

compression test:
1: 110
3: 109
5: 119
7: 122
2: 119
4: 130
6: 125
8: 110

coil setup: running voltage 6.7v to coil. Coil - to pertronix unit, coil + to manifold ground. (still trying to figure out how to operate this coil testing machine I have)

timing set to 4 degrees, base idle set to 500 rpm. Full advance with vacuum coming in at 2500 rpm is 41-42 degrees. Advance module is 11.5 degrees adjustable.

fuel volume rate and flow:
Ten revolutions ov the engine cranking with starter fills 12 ounces.
The Electric pull through fuel pump pushes 10 ounces in 7 to 8 seconds. Fuel pump idling speed pressure is 3psi. Idle pressure with electric pump is 5psi steady.

what further tests are recommended?

 

Plug reading. 16 miles but three to four idling and tinkering hours.
2-4-6-8 left to right
1-3-5-7 top to bottom

AC Delco 4, compression rings removed.

 

I know you have a repair shop, but you mention a modern engine you had to get back to before.
I may have missed your background on older vehicles, not trying to belittle you.
Did you pull a plug wire, hold it away from ground and see how far and what “color” the spark jump is?

You could probably find some calculators online about fuel volume to make sure it’s proper.
The compression test doesn’t reveal a bad issue, but not sure what a fresh 331 would have to compare to.

 

Plug 4 and 5 appears in the pics to not be firing well. After dark, start the car and observe if you see sparks jumping off the wires to ground.

 

I'd throw a new set of plugs and wires in just to rule out that possibility,

 

I'm not sure it is the carb.
You have too much total advance, these engines should max out at 35.
If you have the original dist and coil you might try them...

 

The WCFB is a ****** parts bin! Many fewer parts in a 4 jet.
Also, never rule out a flaky Pertronics, they can drive a guy to drink.

 

Wait a bit, you sure “+” is going to manifold ground and not to the distributor? Don’t think it would even run that way.

 

In a previous thread with 338 replies he mentioned that it was a 1954 Chrysler with a 331 Hemi. Read through it if you want, but you'll probably feel like you're in the "Groundhog Day" movie.

The electrical system is positive ground on these cars.

Here's a link to the dead thread:
https://www.jalopyjournal.com/forum/threads/everybody-is-stumped-with-no-suggestions.1292640/

 

Volume II !

 

I've looked through the thread and can't suggest what you should do. But, I do know what I'd do: install a stock distributor with points and a new coil. Maybe plugs and wires too. Far too many times I and others have chased carb issues when it was a bad condenser, point float, low voltage etc.

And seen too many Petronics stories.

The throttle opening results in higher cylinder pressures, whether or not the revs climb. That pressure increases the voltage needed to jump the gap. Ignition faults can cause problems under those conditions, yet static tests are OK.

may not help but would remove any doubt in your mind along with all us watching.

 

Carburetor is a static object. Kinda need to know what it is on and the health of all the other parts that make it a working part of the engine.

 

Yes, aware of that thread, just struck me odd the coil was at manifold ground.

 

I missed your previous thread, and do not discount any advice here.
I would like to know if you have tried a new accelerator pump,
My experience with the symptoms you ( WCFB ) describe were cured with a replacement

 

My money is still on ignition breakdown.
The following article is very good, and easy to understand. It comes from, of all places, the "Successful Farming" website.
I do doubt whether you will actually read it, but here it is anyway............

HOW TO DIAGNOSE A WEAK IGNITION SYSTEM
By
Ray Bohacz
12/19/2018

At one time or another, we have all been stymied by a gas engine with either a no-start or a hard-start condition, or another performance issue that seems to elude logic. The engine has fuel, spark, and compression. It should either run or not have the performance issue that it does. Often that simple logic does not apply in the real world. Something else is going on, and there is a very strong possibility it is with the ignition.

The ignition system is considered to be p***ive. The spark plug only takes from the ignition coil what it needs to create an arc across the plug’s electrodes. It must be recognized that ignition demand is determined by the following:

• Cylinder pressure
• Engine speed
• Air-fuel ratio
• Ignition timing
• Spark plug gap

Cylinder pressure is not meant to be confused with compression ratio. Cylinder pressure is the ***ulative result of the load on the engine in relation to the volumetric efficiency and mixture strength. Compression ratio is a design function of the difference in the volume of the bore with the piston at bottom dead center, compared to when it is at top dead center. Cylinder pressure and ignition demand are constantly changing with engine load.

At idle, the required energy to arc the spark plug is very low since the cylinder pressure is minimal. This is due to the throttle being almost closed, the engine rpm being low, and the fact that there is no load on the engine.

If the engine was still idled and a load was gently applied (engaging a PTO, for example), the voltage required to arc the plug would increase dramatically. Due to this, the engine may run fine under a given operating state and then buck, pop, and misfire when faced with different operating conditions.

In like fashion, during throttle movement (transient operation), ignition demand spikes just as the throttle plate is evoked. To diagnose a performance issue expediently, you need to remember that electrical demand is linked to load.

WHAT IS A MISFIRE?
An engine is considered to misfire when there is not enough electrical energy going to the spark plug to keep it arcing or there is a path- way in the engine for the energy to take that byp***es the plug’s electrodes. Electricity is lazy. It will always take the path of least resistance. If it is easier to go to ground through the insulation on the ignition wire instead of arcing the gap of the plug under high cylinder pressure, it will. When this occurs, that cylinder will not be contributing full power to the crankshaft. The engine will be weak, the unburned fuel will foul the spark plug, and the exhaust will pop. If the mixture is excessively lean, the engine will misfire since the fuel molecules in the intake air are too far apart. When the mixture is lean, the flame cannot expand across the cylinder bore since it requires both fuel and oxygen to accomplish this.

In most instances, the flame does begin since the air-fuel mixture by design is concentrated around the spark plug electrode. Once the flame expands away from that region, it dies out, and the cylinder is no longer contributing any power. The demand on the ignition will increase, and the energy will look for an easier path.

HOW A PLUG FIRES
A spark plug on most engines fires from the center electrode to the side electrode. That side electrode is grounded via the plug threads to the cylinder head. If the primary leads to the coil were accidently connected in reverse, the amount of energy the coil could produce would be greatly diminished. Most times, the engine would idle fine, but as soon as any load was applied, it would misfire.

The proper connection for a coil is that the voltage from the ignition switch goes to coil (+). Then the wire from either the breaker points or the ignition module goes to coil (-). Many modern gasoline engines do not employ a traditional distributor but, instead, have either a coil on each spark plug or a coil pack that fires two cylinders. When an engine has no distributor, it will use a sensor on the crankshaft to identify each firing event; the sensor also recognizes the number-one cylinder. The control unit is programmed with the correct firing order. This style ignition system allows for longer arcing time of the spark plug when measured in degrees of crankshaft rotation past top dead center. When a coil pack is used, it fires differently than a conventional ignition in terms of polarity. It will fire one cylinder from the spark plug center electrode to the side electrode (normal path) and the companion cylinder from the side electrode to the center electrode.

COMMONLY OVERLOOKED IGNITION PROBLEMS
The following issues can present in different ways or operating states, but the most prevalent are listed below.

1. Cracked spark plug porcelain. This causes misfiring or bucking under load. The engine may run fine at idle and light load.
2. Fouled spark plug. This situation causes misfire (no defined operating state) and hard starting.
3. Weak ignition wire insulation. In this case, the engine runs fine until engine temperatures rise and there is an increase in workload. The wire insulation then breaks down, and the engine bucks or misfires. However, the engine runs smoothly in cooler temperatures or under less workload. When the insulation fails due to heat, it’s because the molecules have moved farther apart, making an alternative path for the electricity to take if that path is easier than jumping the gap of the spark plug.
4. Weak ignition coil. The engine idles fine but breaks up under load. The issue here is a coil that has worn out from the constant charging and discharging cycles. The proper method to check an ignition coil is using an oscilloscope, but an ohm meter works well, too. With the meter, you can check for an internal open in the primary windings or excessive resistance. You will need to check between the primary terminals with the meter leads.

If you have a shop manual for the engine, it usually provides a primary resistance check specification. This is important on pull-type start engines or other small-engine applications.

Keep in mind that it’s possible for the coil secondary to burn open internally. When this happens, the engine will run under light load but will misfire under other conditions. The spark is actually bridging the internal break in the secondary windings, leaving less energy for the spark plug. Older-style ignition coils were oil-filled as a coolant. Later designs were made with epoxy (identified as e-core coils). If you remove the secondary lead from an oil-filled coil and it is wet, the coil needs to be replaced.

CHECK A NO-START
The proper method to check for spark is with a spark tester. It resembles a spark plug but has a sunken center electrode that simulates a load on the coil.

Holding the plug wire and seeing if a spark jumps to ground is inconclusive. The spark is arcing in atmospheric pressure. This is substantially less pressure than the energy required to arc the plug electrode under load.

For an engine to start and run properly, the energy must arc the plug and keep that arc going until all of the combustible mixture is consumed. Anything less and the engine will be weak, run rough, stall, and misfire.

Weak ignition is often confused with a fuel problem since the two systems are codependent. Many times, especially with small engines, the carburetor and the fuel are unjustly demonized for a problem when the ignition system is the real culprit. Think spark first then fuel, not the other way around.

 

Updatelugs are 14-16 miles old, 5-7 running hours.

pertronix pickup: to the folks that don’t know how they work, it’s a simple ground switch. Activated by a magnet p***ing in front of an electronic coil that closes when the magnet p***es within a pre determined air gap,
In my pertronix experience since 2002 (my first instal of a pertronix unit) is that they either work, or the pickup fails and they’re dead. I’ve never seen one work intermittently.

Distributor is the original, and has been gone through by Scotty of parkland Machine and Performance- he is the go to guy in the Pacific Northwest. distributor is setup as follows:
500 rpm 0 mechanical advance
1000 rpm 0
1500 rpm 6°
2000 rpm 12°
2500 rpm 16°
3000 rpm 23°
3500 rpm 26°

plug wires are 14 miles old. Spark videos added here. One video is the origin final Chrysler coil, the other is a brand new Napa coil, part numbers are in the ***les.
Rpm’s from idle to about 2200.

coil power feed voltage is 6.3 volts at idle, and various voltage bouncing when throttled up to 2800 rpm’s because it’s hard to jolt three things at once and my multimeter is old like my truck..:

OK guys, I also found my exhaust gas ****yzer, ironically as I was looking for a missing tool. I absolutely forgot I friggin had it! But it hasn’t been calibrated since 2006, and even in the open air I cannot get the needle into the lean green, so that’s a big fat fail. Ugh….

observing all plug wires and find zero spark jump. It’s dark enough for that test now.

thank you 28 for the share post, I am aware of everything in that article, but I often jump around when I’m diagnosing because I’m stubborn. I rebuilt my first motor in 1985. I’m not new to this, I’m just an idiot sometimes.

Tow truck Tom, yes accelerator pump is brand new, the entire carb has been excruciatingly cleaned, every p***age.

and that’s all I have at the moment without further questions.

https://youtube.com/shorts/3Sbz5EZyTnA?feature=share

https://youtube.com/shorts/4MSsyVFjvy4?feature=share

 

Did you disconnect the secondaries completely yet, and then see what it does?

 

I had to run and buy some pretzels cause I got the munchies as I’m working late. I have not done that because the primary throttle linkage pieces in that area must move out of the way for the secondaries to fully swing open. I’ll show a picture in a few moments.

 

Well, I was wrong you are correct it will open all the way so I’m gonna try that

 

It revs up if I do it slowly, going to hook up my timing light to follow rpm’s

 

She got up to 3560 before getting too much air and not enough fuel on the secondary blades.

I am totally feeling now that this thing is still too lean with .094 primaries and .062 secondary jets.

 

Since the secondary linkage is now disconnected, I can run primaries up to full and see if it does it on the primaries still

nope it starts doing the same thing right about 2800 RPMs and I can’t run the primaries all the way open so that means I need another step up on my primary jets also I believe.

when Jon said they were four and six sized too lean I was shocked. I don’t know how that lean of jetting hasn’t burnt holes in the pistons.

 

Couple of things.......

1) I'm guessing the Napa LC7SB coil you are using is rated at somewhere around 1.5 ohms.

2) The following info states a 0.6 ohm coil for a Pertronix igniter on a V8 with a 6 volt system.
http://www.pertronix.com.au/flame-thrower_coil_1.html

3) If your coils resistance is high, there is less amperage p***ing through the coils and points, which would extend their life, although excessive resistance results in a weak spark, and frequently, misfires.

 

Yes, then it is, in fact way lean. It should rev all the way up on the front barrels .It's gonna be slower...you know, like a 2 bbl. ;-)

 

That Napa coil is a 6volt system coil, IC7SB There’s no specs about ohms on their site.

 

I guess I’m going to call John’s shop tomorrow if they’re open and order several larger sized for this damnable carb

 

I noticed in your video of the spark. When the engine hiccuped the spark went away.

 

here’s a little of my thoughts.

pertronix unit does not give the tiniest bit about voltage or ohms or resistance or chamber pressures. The only thing thing this little thing does is open and close, when it is open, there is the coil dwell time to saturate and charge, when it’s closed, that charge continues through the time my unit and out to the plug to complete its journey to the ground strap from the center electrode.

the pertronix is simply a solid state contact.

Their coils are an up sell, yes 40k volt spark is better than 20K spark. But that has no correlation to the pertronix unit it’s self. It’s simply an open or closed switch.

Also, I have never heard a convincing statement to dissuade me from my understanding of what the unit does.

 

Yes I saw that too. But using the secondary blades only I got to 3560 rpm without the slightest stumble. I am not convinced it’s spark loss. Because the primaries stumble and pop at 2800 rpm’s.

that stumble at two different areas of the carburetor at different rpm’s, cannot be spark ****ter.