I’ve heard and read about but not tried this method of setting total advance. It sounds like you were trying to accomplish the same as I am: get full advance in quicker for better throttle response. I’ll be back in the shop today and will hopefully get everything sorted out.

 

Source ..
Source ..

 

[QUOTE=Go Seahawks!;20007974]…I still don’t understand some things, like why does my system have a condenser attached by a bracket to the module, wired into the incoming side of the module, from the factory? Also, why does the existing ignition module (NAPA TP35) have only 2 wires going out into a 3 wire factory harness plug?

I learned the condenser is actually a capacitor to filter ignition radio noise. No idea why it doesn’t show on any electrical diagram I’ve seen.

Still no idea exactly “why” on the 2 module wires into the factory 3-wire plug but I’m positive this is a factory 6 wire Duraspark I module system (black 1974 only grommet with 4 wires in and 2 out) with matching factory wiring. Not a blue wire in sight as shown on every DS1 diagram I’ve seen but there IS a pinkish colored wire in the power-out side of the factory harness that is not used. I don’t know where it goes.

 

Condensers were used in Distributors with points. There engineered purpose is defined below. The reduction of radio noise is a secondary benefit. This is more than likely a ballast resistor and present in the Dura spark I setup. Here's a good read on the history of coils and the ballast resistors place in that history.
I've got more to say on the topic but it will have to wait for now.

 

The Hemmings article is a good read. After reading it I did some research on resistors and found the reduced voltage to the coil was accomplished through a resistance wire from the ignition switch. That makes sense since the positive wire to the coil is red (from ignition switch) not blue (from the module).

Here’s a pic of my module with the condenser-shaped device attached with a bracket to it as well as the wiring in and out of the module itself that doesn’t match up to anything I’ve seen online. I “think” the cylinder device is an ignition radio noise filter (?) but again, it doesn’t show in any wiring diagram I’ve seen.



So… I’ll bite. What more do you have on the topic?

BTW, I spent time yesterday trying to work my way through my ignition woes, unsuccessfully. I actually walked away with even more questions about what was going on:
*Still backfires between 1800-2000 RPM but goes away by 2100 or so and doesn’t come back by 3000 (max revs. I get really nervous under the hood at these higher engine speeds).
*I can’t get total advance higher than 29 or 30* at 3000 RPM with initial at 14-15*. That was with 2 different spring combos. Changing springs seemed to have little or no affect on advance. I also adjusted the spring tabs trying to affect a change in the advance with little to no affect. The tabs are bent just enough to take up any slack so the aren’t loose on the posts.
*It won’t start with vac advance connected (ported source). Just cranks. Starts right up disconnected. If I connect the vac line while it’s running it continues to run but when I crack the throttle it bogs and would die if not returned to an idle.
*I decided to start from scratch and time TDC with the distributor. I brought #1 cylinder to TDC and confirmed that with the timing mark on the balancer. Then I rotated the engine to 12* BTDC on the timing mark and twisted the distributor so the center of the rotor lines up exactly with the center of the magnetic pickup. This was a lot of movement from where it had been set previously, like 1/2” + where it goes into the block. I tried starting and for a huge cough through the carb. I slowly nudged the distributor to retard timing until it would start with coughing then set it to 12*. The distributor ended in exactly the same place it started BEFORE I started this exercise.

So how does this happen?? If I set it at 12 or any other initial when the engine is static, why does it change when running? And therein lies the answer!

It hit me like a ton of bricks and explains all the symptoms: the springs are much too loose. They are adding mechanical advance at idle when initial is being set! Close to 15*! No wonder there’s no advance much past 2500 RPM and less than 30* all-in. I’m started initial from a retarded position to make up for the mechanical that’s being added, which is 50% of the total advance I can expect from a 15L slot.

This is only theory until I can get back in the shop and play around with spring tensions, but I’m confident in the direction I’m going.

 

You've been busy

Some Dura-Spark II system equipped models use a dual mode timing system. The dual mode timing system uses a 3-connector electronic control module. This connector is attached to a switch. The switch is either a distributor modulator valve, used in engines with the fuel economy package, or an ignition barometric pressure switch used in engines for operation in high altitudes.

Dura-Spark I - This ignition system uses a solid state distributor, primary wiring, coil, and an electronic control module. Special 8 mm spark plug wires and wide gap spark plugs are used. We're looking for a ballast resistor has a value of 1.35 ohms. On Dura-Spark I systems, the module contains a coil current regulator. This regulator will turn off current not rotating. To turn primary circuit back on, the ignition switch must be turned to the "START" position.

So unless your vehicle is a Calf. vehicle it isn't a Dura Spark I but mostly a Solid State Ignition distributor. and the wiring diagram looks like the following.



First let's get the ballast resistor question out of the way by performing the following test.

To check for ballasted or unbalasted:

Connect a multimeter to the ignition side of your coil (usually the positive side) and ground, and then turn the ignition on. If you get a reading of between 6 and 9 volts, you have a ballasted system. If, on the other hand, you get a reading of around 12 volts, you have an non-ballasted system.

The next thing I'd check to make sure you haven't sheared the distributor gear pin. Sometimes when an engine sits for awhile on start up this can happen. It's the weak link. Inspect closely because the pin can appear to be intact but is broken between the shaft and the ID of the gear. When this happens it won't spin necessarily freely because it's not a clean break but it will spin rather roughly when the gear and shaft are held independently and rotated in opposite directions.

Get those two things out of the way and will go from there.

 

Go Seahawks,
Commend you for hanging there trying to resolve your 400 timing issue. Can't offer you any technical advice as Red Road has been.
You may of read, I was having a timing issue with my 1977 F-150, 400 and resorted to purchasing a remanufactured Motorcraft (AutoLite) Dura Spark distributor from Rock Auto, which resolved my timing issue. I'm not advocating to purchase a remanufactured in Canada Auto Lite distributor, simply relaying what worked for me. Although my 77 F-150 isn't a daily driver, I did have to move it during my second week of vacation in order to perform annual maintenance (pressure washing) the house and knew I couldn't push the truck back up the driveway once I would of rolled down, so I resorted to the remanufactured distributor. Truck is running well now, just need to re-adjust idle once it's warmed up (swapped over to Holley 2300 EFI). Plan on driving it to work the remainder of the week, the computer needs to be able to do the self learning mode.

 

I’ve been busy. Family time has been conflicting with truck time. Tomorrow I’m planning on getting back onto it and will post my results. Thanks for all the helpful advice!

 

Life has gotten in the way. I was able to get a little time in a couple days ago but everything I did only led to another question. It’s not that difficult but I just can’t get the timing to dial in no matter what I try. I’ve ordered a new (rebuilt OEM) distributor from Rock Auto. We’re leaving tomorrow for a 2 week camping trip so this little project will have to be back-burnered until we get back. I will post results for anyone interested in how this turns out.

 

Have a great time camping and hopefully you won't give it another thought until you get back. BTW the pink wire is more than likely your ballast resistor. Talk to you when you get back.

COLF-12250-A .. Resistor Wire-Ignition Coil (Motorcraft DY-37)

61" long / 1.30-1.40 ohms resistance / Color coded Pink / #16 gauge wire.

 

Ok, I’m back. I received the new distributor from Rock Auto. Looks like OEM. Advance slot came set on 18L and there looked to be one stiff and one medium advance spring. After some setbacks due to the oil pump
shaft coming unseated when I removed the old distributor, and consequently not being able (thankfully) to seat the new distributor until that little issue was resolved, today I resolved those problems and got the new distributor in place. I set initial time at 12 degrees BTDC (timing pointer on balancer set at that mark and the distibutor rotor centered on #1) and tried to fire it. It drug hard on the starter so I retarded it a bit, maybe 2 degrees. It fired and ran albeit rough. I put a timing light on it and it was 48-49 degrees BTDC. WTH. I backed initial down to zero and fired it off again. Now it was down to 45 degrees. I stopped there. Any thoughts on why timing is all-in at idle?? How is this even possible? Basically the same thing that was happening with the old distributor. I’m stumped.

 

I'm not sure what you mean, if it's 45 at idle that is your initial so you need to back it off another 35 degrees then check your all in.

it's what the timing light says that matters.

 

Retarding it to see what happens is the next step but before I do that I was hoping to better understand why I’m not seeing timing with a light the same as what I set it at initially on the balancer. Shouldn’t they should be the same unless the distributor is mechanically advancing at idle, or am I missing something?

 

If your balancer has slipped it would be off the same amount with the light as setting it up . if you haven't already you should verify it's truly on TDC.

The only advance in your system is the mechanical weights and the vacuum advance can. your vac advance should be disconnected and your mechanical advance doesn't have the range to advance you 45 degrees even if it were stuck all in. so it has to be something simple you're fighting.

When you say setting it on the balancer do you mean putting the timing marks on TDC then aiming the rotor at #1 in the distributor cap ?

 

I’m positive on TDC and it lines up with the timing mark in the balancer. Vac advance is disconnected and plugged. Timing on balancer is set as you describe in your last question.

The distributor timing advance slot is 18L. That should provide 36* mechanical advance. The springs regulate the progression relative to engine RPM. I get all that. I’ve recurved enough GM HEI’s to understand at least the basics. This is my first Duraspark. I’m missing something and like you said it’s probably simple and staring at me. I plan on giving it another go today.