Journeyman
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Hey glad to hear you got yours working... I hope to get my MC2100 tomorrow and the adapter was ordered this morning. 
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Way Outta Control
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A little theory about timing/advance.
To light the fire in the chamber, then let it burn till it's at it's maximum pressure it takes time - about the same time whether at idle or 10,000 RPM.
At idle the engine is turning slowly, so you only need to light it a few degrees ahead of time. The faster the engine goes, the sooner in degrees you have to light it.
That;s why we adjust it according to engine speed.
Then there are 2 basic curves we look at. One "advance" curve is for power, there's the "Ideal point" at any RPM where the maximum power is generated. But, we also like economy, max efficiency is not the same curve as max power. Similar, but different.
So - we set the mechanical system's curve to follow the power curve, and the vacuum system to follow the efficiency (mileage) curve. We end up with the best of both worlds.
Ported vacuum nearly follows the efficiency curve, yet it too helps with the power. The ported vacuum is derived from holes or slots right near the edge of the butterfly valve. As the R's increase, the vacuum increases - to a point. It advances the timing more - above the power curve to follow the efficiency curve. That works to about 60 opening of the throttle.
But, sometime we want full power. Ported vacuum also goes away, drops back down at openings above that 60% point. Under full punch it goes away completely, dropping the total advance back down onto the power curve.
Very convenient!
So yes, you could say they both work together at the same time - most of the time.
Another very important thing - the TOTAL or max advance, should be kept to 35 degrees or less. Reason being above that creates too much cylinder pressure, shortening the life of the rings. Yes, race cars often use much more advance than that, sometimes as much as 60 degrees advance. But those engines aren't expected to last long. In a Jeep or most of our applications we'd like it to last a long time.
Now - for a different perspective - the best place for combustion pressure to be at it's fullest - mechanically speaking, is for max cylinder pressure to occur between 32 and 37 degrees AFTER TOP DEAD CENTER. That gives the maximum mechanical advantage of pushing down on the piston. Remember it takes time to develop max pressure, we have to light the spark early to achieve that.
So, at 2900 RPM we may have 35 degrees BTC in the ignition, but the peak pressure is 70 degrees after that! (35BTC+35ATC).
Much like a BBQ, you can't cook steaks immediately after lighting it - it has to develop good heat first - taking time.
Disconnecting the vacuum to set initial guarantees there is no vacuum advance.
Do the propane trick, it will tell you where you are - lean or rich at ALL SPEEDS and under all conditions.
To light the fire in the chamber, then let it burn till it's at it's maximum pressure it takes time - about the same time whether at idle or 10,000 RPM.
At idle the engine is turning slowly, so you only need to light it a few degrees ahead of time. The faster the engine goes, the sooner in degrees you have to light it.
That;s why we adjust it according to engine speed.
Then there are 2 basic curves we look at. One "advance" curve is for power, there's the "Ideal point" at any RPM where the maximum power is generated. But, we also like economy, max efficiency is not the same curve as max power. Similar, but different.
So - we set the mechanical system's curve to follow the power curve, and the vacuum system to follow the efficiency (mileage) curve. We end up with the best of both worlds.
Ported vacuum nearly follows the efficiency curve, yet it too helps with the power. The ported vacuum is derived from holes or slots right near the edge of the butterfly valve. As the R's increase, the vacuum increases - to a point. It advances the timing more - above the power curve to follow the efficiency curve. That works to about 60 opening of the throttle.
But, sometime we want full power. Ported vacuum also goes away, drops back down at openings above that 60% point. Under full punch it goes away completely, dropping the total advance back down onto the power curve.
Very convenient!
So yes, you could say they both work together at the same time - most of the time.
Another very important thing - the TOTAL or max advance, should be kept to 35 degrees or less. Reason being above that creates too much cylinder pressure, shortening the life of the rings. Yes, race cars often use much more advance than that, sometimes as much as 60 degrees advance. But those engines aren't expected to last long. In a Jeep or most of our applications we'd like it to last a long time.
Now - for a different perspective - the best place for combustion pressure to be at it's fullest - mechanically speaking, is for max cylinder pressure to occur between 32 and 37 degrees AFTER TOP DEAD CENTER. That gives the maximum mechanical advantage of pushing down on the piston. Remember it takes time to develop max pressure, we have to light the spark early to achieve that.
So, at 2900 RPM we may have 35 degrees BTC in the ignition, but the peak pressure is 70 degrees after that! (35BTC+35ATC).
Much like a BBQ, you can't cook steaks immediately after lighting it - it has to develop good heat first - taking time.
Disconnecting the vacuum to set initial guarantees there is no vacuum advance.
Do the propane trick, it will tell you where you are - lean or rich at ALL SPEEDS and under all conditions.
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You SHOULD first use a vacuum gauge to set your idle mixture...
Screw both idle mixture screws 'IN' until the GENTLY bottom out, then back them out about 2.5 turns EACH.
Then start, warm up the engine with a vacuum gauge attached to the BASEPLATE vacuum, not the spark ported vacuum, and not to the manifold vacuum if you can help it!
With BASE PLATE vacuum showing and warm, ideling engine,
Screw the idle mixture screws in TOGETHER,
They must ALWAYS MOVE TOGETHER...
Screw them in until you read a good no load idle mixture on your idle mixture gauge,
OR until you get the highest STEADY vacuum reading.
If you go too lean, you will see UNSTEADY vacuum readings, and if you continue to lean out, you will get popping and lean misfire....
Continue turning the screws in about 1/8 to 1/4 turn TOGETHER until the engine dies.
If the engine won't die with the screws LIGHTLY bottomed out (DO NOT CRANK DOWN ON THEM!),
You have an internal fuel leak,
Blown power valve, siphoning fuel from accelerator pump, something like that.
If it DOES die, Then you are actually controlling the fuel mixture like they are supposed to do,
Back them back out to about 2.5 turns each, and then use the vacuum gauge to set them at the highest STEADY vacuum reading again, and you will be VERY close to the proper fuel mixture...
Then you can move on to power valve assessment with a vacuum gauge....
WOW! This is so wrong I don't know where to begin!
The vacuum reading on power valves is the CLOSING POINT, not the OPENING POINT.
When you start the vehicle, the power valve is OPEN.
No vacuum means OPEN POWER VALVE.
There isn't any air moving through the carb with the engine not running, so there isn't any fuel being drawn into the venturis, so it's JUST FINE for the power valve to stay open when there is no vacuum!
When the engine starts, and vacuum rises, the power valve CLOSES at the vacuum point listed on the power valve.
(More or less, power valves vary from manufacturer to manufacturer... Holley valves are usually right on the money, while the 'Import Crap' can be anywhere on the vacuum scale, if it closes at all!)
When you are running down the highway, you will probably have around 8 In.Hg. vacuum in the engine, under load, with throttle blades partly open...
What we call 'Part Throttle Cruise'...
When you tip into the throttle, opening up the blades just a little, like to keep up with a vehicle in front of you...
The power valve SHOULD NOT open...
If you tip into the throttle for rapid acceleration, like to pass someone, the vacuum will drop to almost nothing the instant the throttle blades are opened,
and the power valve is there to add fuel to the engine during these large throttle movements...
SO!
If your PART THROTTLE CRUISE (PTC) vacuum reading is about 8.5 In.Hg. on the gauge,
You should be running about TWO INCHES HG LOWER POWER VALVE,
In this case, 8.5 minus 2 equals a 6.5 In.Hg. power valve.
If you are a SERIOUS off roader, and have your Jeep wedged into some 'Situations' on obstacles you have to 'Finesse' your way out of,
Then drop EVEN MORE... So the power valve doesn't open when you are at very low RPM, have the throttle most the way closed, and only want a 'Bump' instead of a JUMP!
I keep mine at about 2.5 In.Hg. below my highway 8.5 PTC reading.
If you want a 'HOT ROD',
Then do LESS than two inches Hg. below the 8.5 reading.
Around 7.5 so the extra fuel starts faster when you open the throttles just a little bit.
If you ran a 10.5 power valve, the power valve would be open all the time you were in gear or moving, and that defeats the objective of the power valve entirely...
--------------------------------------------------------------
Screw both idle mixture screws 'IN' until the GENTLY bottom out, then back them out about 2.5 turns EACH.
Then start, warm up the engine with a vacuum gauge attached to the BASEPLATE vacuum, not the spark ported vacuum, and not to the manifold vacuum if you can help it!
With BASE PLATE vacuum showing and warm, ideling engine,
Screw the idle mixture screws in TOGETHER,
They must ALWAYS MOVE TOGETHER...
Screw them in until you read a good no load idle mixture on your idle mixture gauge,
OR until you get the highest STEADY vacuum reading.
If you go too lean, you will see UNSTEADY vacuum readings, and if you continue to lean out, you will get popping and lean misfire....
Continue turning the screws in about 1/8 to 1/4 turn TOGETHER until the engine dies.
If the engine won't die with the screws LIGHTLY bottomed out (DO NOT CRANK DOWN ON THEM!),
You have an internal fuel leak,
Blown power valve, siphoning fuel from accelerator pump, something like that.
If it DOES die, Then you are actually controlling the fuel mixture like they are supposed to do,
Back them back out to about 2.5 turns each, and then use the vacuum gauge to set them at the highest STEADY vacuum reading again, and you will be VERY close to the proper fuel mixture...
Then you can move on to power valve assessment with a vacuum gauge....
Quote:
Originally Posted by zshooter1
View Post
No vacuum leaks, no EGR problems, too lean probably means ignition is good. A 6.5 power valve is a "late opener" - doesn't open until engine vacuum falls below 6.5 hg.
That's basically when you floor it, for the first few seconds you have WOT (as in passing cars on the highway).
One other way to enrich your mixture is to get an "earlier opening" power valve - I think a 10.5 is the "earliest" Holly sells.
That's basically when you floor it, for the first few seconds you have WOT (as in passing cars on the highway).
One other way to enrich your mixture is to get an "earlier opening" power valve - I think a 10.5 is the "earliest" Holly sells.
The vacuum reading on power valves is the CLOSING POINT, not the OPENING POINT.
When you start the vehicle, the power valve is OPEN.
No vacuum means OPEN POWER VALVE.
There isn't any air moving through the carb with the engine not running, so there isn't any fuel being drawn into the venturis, so it's JUST FINE for the power valve to stay open when there is no vacuum!
When the engine starts, and vacuum rises, the power valve CLOSES at the vacuum point listed on the power valve.
(More or less, power valves vary from manufacturer to manufacturer... Holley valves are usually right on the money, while the 'Import Crap' can be anywhere on the vacuum scale, if it closes at all!)
When you are running down the highway, you will probably have around 8 In.Hg. vacuum in the engine, under load, with throttle blades partly open...
What we call 'Part Throttle Cruise'...
When you tip into the throttle, opening up the blades just a little, like to keep up with a vehicle in front of you...
The power valve SHOULD NOT open...
If you tip into the throttle for rapid acceleration, like to pass someone, the vacuum will drop to almost nothing the instant the throttle blades are opened,
and the power valve is there to add fuel to the engine during these large throttle movements...
SO!
If your PART THROTTLE CRUISE (PTC) vacuum reading is about 8.5 In.Hg. on the gauge,
You should be running about TWO INCHES HG LOWER POWER VALVE,
In this case, 8.5 minus 2 equals a 6.5 In.Hg. power valve.
If you are a SERIOUS off roader, and have your Jeep wedged into some 'Situations' on obstacles you have to 'Finesse' your way out of,
Then drop EVEN MORE... So the power valve doesn't open when you are at very low RPM, have the throttle most the way closed, and only want a 'Bump' instead of a JUMP!
I keep mine at about 2.5 In.Hg. below my highway 8.5 PTC reading.
If you want a 'HOT ROD',
Then do LESS than two inches Hg. below the 8.5 reading.
Around 7.5 so the extra fuel starts faster when you open the throttles just a little bit.
If you ran a 10.5 power valve, the power valve would be open all the time you were in gear or moving, and that defeats the objective of the power valve entirely...
--------------------------------------------------------------
So Many Cats, So Few Recipes...
Last edited by TeamRush; 07-01-2009 at 12:41 AM.
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Quote:
Originally Posted by RRich
View Post
My feeling - ignition.
1. The TFI coil MUST HAVE A FULL 12 VOLTS TO IT AT THE + TERMINAL. Check it while running, not with the engine off, key on. The old ignition resistance wire or resistor MUST BE BYPASSED!
1. The TFI coil MUST HAVE A FULL 12 VOLTS TO IT AT THE + TERMINAL. Check it while running, not with the engine off, key on. The old ignition resistance wire or resistor MUST BE BYPASSED!
Again, I just don't have words for how WRONG this is!
The MODULE must have somewhere above 10.5 volts to operate correctly.
The coil can see as little as 4.5 volts and still operate!
(not at peak efficiency, but still OPERATE just the same!)
The RESISTOR WIRE DOES NOT HAVE TO BE REMOVED!
And shouldn't be removed if you are still running a factory style Jeep/DuraSpark ignition module!
If you want to replace the Factory Jeep/DuraSpark ignition module with a 'Stealth HEI' or some other module that is capable of handling a full 12 volts with a short saturation time coil, then feel free to remove the resistor wire,
But it's not even mandatory then....
The ONLY time the resistor wire MUST be removed (Mandatory) is when you are running a CDI (Capacitive Discharge Ignition) module, and since you said NOTHING about the CDI module...
---------------------------------------------------
Quote:
Originally Posted by RRich
View Post
2. Check the advance - you said 10 degrees at idle - that must be with the distributor vacuum disconnected! The distributor vacuum MUST BE PORTED VACUUM - near 0 at idle, smoothly progressing as the R's are raised.
BUT,
You WILL find vacuum at idle with a Ford carb...
He IS correct about unplugging the vacuum advance from the distributor,
But he failed to mention you need to PLUG that vacuum line with something (like Golf 'T') while you are doing the timing....
And you DO want to use a timing light to set the timing.
Personally, I Feel that 10 degrees Initial is too much,
Should be back around 6 degrees or so,
Or even with the large cap you can fire the wrong spark plug terminal when the vacuum advance comes in...
------------------------------------------
Quote:
Originally Posted by RRich
View Post
3. Use a timing light - vacuum disconnected - it should SLOWLY advance to about the low 20's at about 2000+ RPM. That's the mechanical advance.
Starting somewhere between 800 & 1,000 RPM,
And be all in by about 2,100 to 2,300 RPM
With your 10 degrees Initial, and a minimum of 15 degrees of CENTRIFUGAL advance,
(Everything in this distributor is 'Mechanical' so it's all 'Mechanical' advance,
Separate the three types of advance as INITIAL, CENTRIFUGAL and VACUUM)
So you are starting with about 10 degrees of INITIAL,
Then adding about 13 to 18 degrees of CENTRIFUGAL,
You should be showing about 23 to 25 degrees, and might go as high as 28 since some distributors have as much as 21 degrees advance from the factory in the Centrifugal advance head...
Here is a picture of the 'Average' AMC I-6 distributor centrifugal advance head,
And you can CLEARLY see the markings are for '18' & '21' from the centrifugal advance weights...
Some will be marked '15' & '18' on the V-8 distributors...
Some of the 'Computer Controlled' engiens will have distributors that have 'RETARDED' Timing, meaning the 'Advance' is actually different degrees of 'Retard controlled in the under hood computer...
Your advance will only show about 5 or 7 degrees of centrifugal advance,
And in that case, you will have to RE ORIENT the reluctor on the advance head shaft...
(much easier than it sounds) to make up for the computer that is no longer controlling the advance...
Then you can make the advance head limiting slots longer to get more centrifugal advance or swap out distributors for something that will work better for you...
This should be a new concept for 'Internet Experts' like Rich and the others since I haven't covered it here before and they haven't had the opportunity to plagiarize it yet,
And I haven't published a 'Tech Article' about it...
(since I didn't get paid for the last one, I probably won't)
But the last two years of CJ and all the YJ's have the 'Retarded' trigger in the distributor and need to be corrected...
--------------------------------------------------------
Quote:
Originally Posted by RRich
View Post
4. Connect vacuum, check advance again - it should SLOWLY advance to about 35 degrees at 2800.
If in either case it "jumps" or "slams" from low to high advance - fix that.
If in either case it "jumps" or "slams" from low to high advance - fix that.
This advice doesn't work very well...
The I-6 timing scales usually only show about 20 degrees, so you will have to modify something somewhere to show the entire advance curve...
Personally, I use a piece of chalk since I normally only have to do this ONCE, but you can buy balancers that have up to 90 degrees of timing marked on them,
Or you can buy a $4 timing tape that just sticks on the balancer to make the needed scale for you...
If you line your harmonic balancer 'Hash' mark up with the 0° (zero) mark on the timing scale (TDC),
Then back the balance up 10 degrees (with the balancer 'Hash' mark on the 10°),
And mark the balancer again at 0° (zero)...
Then back the balancer 'hash' mark up to the 20° indicator on the timing scale,
And mark the balancer again at the 0° mark on the scale...
You will have enough 'Scale' to complete mapping of your ignition advance properly...
Balancer 'Hash' mark... with the first made line on the 18° indicator means 18 + 10 degrees or 28 degrees...
Easy and simple once you get the hang of it and learn how the ignition/scale works.
----------------------------
Quote:
Originally Posted by RRich
View Post
5. Pull off a plug wire at the plug - look at the spark as it jumps to ground. It should be a scary sounding, snappy, blue/white spark at least 3/4 of an inch long. If not, find out why.
Taking the ground away from a high voltage wire (ground is the spark plug) is a REALLY bad idea!
When you take the ground away, it's the same as jacking the spark gap open to about an inch or so,
And the coil will either discharge internally, damaging the insulation and windings (Especially with the E-core coils),
Or it will jump to ground inside the cap somewhere it's not supposed to...
MUCH better idea is to use a TEST PLUG.
You can make a test plug out of an old spark plug, and some insulated wire to ground the plug.
Strip back about 3" of insulation,
Wrap it around the threads of the plug,
Then strip about 3" of the other end of the wire, and wrap it around the battery negative terminal.
This gives you a CONTROLLED GAP to have a look at the spark in the gap,
AND you don't have to worry about grounding issues.
Electronic Ignitions should NEVER be 'Open Ground',
And I'm not crazy about those cheap spark voltage testers, since voltage is only one SMALL part of Spark Energy...
You should be more concerned with AMPERAGE, The 'Heat' the spark has,
And the DURATION, the amount of time the spark exists in the plug gap.
VOLTAGE only ionizes the spark gap,
And driving voltages up with large gaps only robs the Spark Energy Discharge of AMPERAGE & DURATION.
I could go on, but it's pointless since the 'Issue' stands out like a sore thumb!...
So Many Cats, So Few Recipes...
Way Outta Control
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That tirade contains about 30% truth, the rest wives tales.
You are using the HEI module, and if I remember right, the TFI coil. Neither HEI or the TFI systems use an ignition resistor - that's a resistor in series with the coil, not the module. They are designed to get the full benefit and current from an unrestricted 12 volts.
True, the HEI module needs 12 volts to operate - to switch on and off. But the main source of power for the spark comes from the voltage supplied to the coil. Yes, it may run on as little as 4.5 volts, but not well - it will probably stumble like crazy. It needs a full low resistance 12 volts to the + side of the coil.
The "expert" has had many posts where he's said it's so important he uses a separate relay to supply that 12 volts. That's a bit overboard, but if it doesn't get the full 12 volts the ignition is weak, possibly causing stumble.
Even funnier, now he says if the original Ford module is used, it must have the ignition resistor. A complete reversal from what he used to say. That's the true part of the tirade.
And the "expert" believes the wives tale that pulling loose a plug wire will cause damage to the system, hurting the coil, arcing in the cap etc. I suppose the stupid engineers didn't consult him, they never even thought a plug wire can come loose or break? They never designed in that extra insulation to prevent damage? What a pity
True, the voltage will rise to it's potential - about 40KV, if that ruins the insulation in the cap or coil, that weak insulation may very well be the source of the stumble.
Funny too - he claims it's not possible to watch the advance slowly move - simply watch it as you rev it up. If it jumps up, it's not right.
And I guess he's never heard of such a new fangled device called an advance timing light to actually read the amount of advance.
So - try the suggestions I've made, or follow his advice - your choice.
You are using the HEI module, and if I remember right, the TFI coil. Neither HEI or the TFI systems use an ignition resistor - that's a resistor in series with the coil, not the module. They are designed to get the full benefit and current from an unrestricted 12 volts.
True, the HEI module needs 12 volts to operate - to switch on and off. But the main source of power for the spark comes from the voltage supplied to the coil. Yes, it may run on as little as 4.5 volts, but not well - it will probably stumble like crazy. It needs a full low resistance 12 volts to the + side of the coil.
The "expert" has had many posts where he's said it's so important he uses a separate relay to supply that 12 volts. That's a bit overboard, but if it doesn't get the full 12 volts the ignition is weak, possibly causing stumble.
Even funnier, now he says if the original Ford module is used, it must have the ignition resistor. A complete reversal from what he used to say. That's the true part of the tirade.
And the "expert" believes the wives tale that pulling loose a plug wire will cause damage to the system, hurting the coil, arcing in the cap etc. I suppose the stupid engineers didn't consult him, they never even thought a plug wire can come loose or break? They never designed in that extra insulation to prevent damage? What a pity
True, the voltage will rise to it's potential - about 40KV, if that ruins the insulation in the cap or coil, that weak insulation may very well be the source of the stumble.
Funny too - he claims it's not possible to watch the advance slowly move - simply watch it as you rev it up. If it jumps up, it's not right.
And I guess he's never heard of such a new fangled device called an advance timing light to actually read the amount of advance.
So - try the suggestions I've made, or follow his advice - your choice.
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TeamRush, didn't we just give the same definition of the power valve function?
I appreciate all the knowledge you share on these forums. I've upgraded my ignition based on your instructions, and it works GREAT!
I appreciate all the knowledge you share on these forums. I've upgraded my ignition based on your instructions, and it works GREAT!
Quote:
Originally Posted by TeamRush
View Post
"If you tip into the throttle for rapid acceleration, like to pass someone, the vacuum will drop to almost nothing the instant the throttle blades are opened, and the power valve is there to add fuel to the engine during these large throttle movements...
Quote:
Originally Posted by zshooter1
View Post
A 6.5 power valve ... doesn't open until engine vacuum falls below 6.5 hg. That's basically when you floor it, for the first few seconds you have WOT (as in passing cars on the highway)
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Quote:
Originally Posted by ORIGINAL POSTER
Not sure if my carb is a 2100 or 2150 now. labeled motorcraft on the top of the carb, but stamped 1.08. I'm hesitant to say that it makes a difference, I don't think so.
2150 had the solenoid,
2100 has a 'Flat' back.
The solenoid is an altitude compensation device, and it REALLY doesn't make any difference!
-----------------------------------------------
Quote:
Originally Posted by zshooter1
View Post
TeamRush, didn't we just give the same definition of the power valve function?
I appreciate all the knowledge you share on these forums. I've upgraded my ignition based on your instructions, and it works GREAT!
I appreciate all the knowledge you share on these forums. I've upgraded my ignition based on your instructions, and it works GREAT!
My jeep NEVER sees 10.5 InHg vacuum when in operation!
So the power valve would never CLOSE!
Vacuum based (Engine Load Based) Axillary fuel enrichment is WORTHLESS if it's always OPEN or always CLOSED!
-------------------------------
Rich,
There ARE NOT any FACTORY DuraSpark modules left anymore, Haven't been any since Motorcraft stopped making them in 1993.
The CHEAP, AFTERMARKET modules DO NEED a resistor to live...
And most won't live with a change as small as going to a faster saturating ignition coil...
FACTORY MODULES will live without resistor,
Aftermarket modules WILL NOT.
Since I haven't been able to buy a reasonable module from anyone since 2002 when MSD stopped making their version,
I doubt anyone else has a main line to a warehouse full of Original Ford/Motorcraft modules either...
SO!
If you have an 'Original' Motorcraft/DuraSpark module,
It's 23+ years old, and it's been mounted next to the exhaust manifold for all 23+ years...
It *MIGHT* live up to not running a resistor, but with an E-core coil, I don't think that 23+ year old module will survive,
BUT! You can try it if you want to!
I don't have time to pick you apart right now, I have people wanting HELP with things,
Maybe later if I'm bored...
-------------------------
As to the other crap,
Go with the guy that PLAGIARIZES all he knows from my posts,
Or go with the guy that knows the systems and WRITES the dissertations,
Puts together the upgrades,
And shows pictures of the damaged parts when things go 'Wrong',
And WHY you should upgrade...
-------------------
Every high voltage discharge that can't properly ground WILL find ground somewhere!
If you pull a spark plug wires off...
The voltage will build until the spark energy discharges, it's just an electrical principal you can't change.
If there isn't a SAFE ground, like a spark plug,
Or jumping to ground inside the distributor,
(which causes carbon tracking and burns/blows chunks out of the graphite center terminal)
Then it's going to ground INSIDE the ignition coil...
EVERY SINGLE DISCHARGE burns away insulation on the wires, so the winding short out,
Over time, that renders the coil useless.
Again, this shows a complete lack of the understanding of electrical principals and practice...
So Many Cats, So Few Recipes...
Last edited by TeamRush; 07-01-2009 at 02:59 PM.
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TR - you keep thinking the guy has the Ford module - original or not!
Look at his post #1 ----- READ IT!
His first sentance ------
""""""vehicle: 88 YJ 4.2 A/T HEI ignition module, ford dist cap, base and rotor, MC2100 from early 80's Ford van(currently the one with the problem)"""""
IT'S AN HEI! Ford never made an HEI - it's a patented copywrited name for the GM High Energy Ignition!
And according to the first sentence he's also using a Ford Cap - so obviously it's not a GM "built-in" coil. If I remember correctly for previous posts, he's using a TFI coil. He also says he's using the Ford cap, base and rotor, that would be the big cap that YOU always recommend.
The big cap and the GM cap have better insulation than the older smaller ones. The terminals are spaced farther apart and they have insulation ridges inside as barriers to increase the insulation (or should.) THEY ARE DESIGNED TO WITHSTAND THE HIGHER VOLTAGES GENERATED BY THE HEI OR TFI SYSTEMS.
Open circuiting - pulling a plug wire - or having one break or come loose IS NOT AN UNCOMMON OCCURRENCE. The coil voltage will go to it's maximum potential - conventional ignitions about 30 KV, HEI and TFI about 40 KV. There are aftermarket coils that advertise more, but they are bullsh--. It's easy to test. Rising to it's fullest is not harmfull at all. IF THE INSULATION OF THE COMPONENTS IS STILL WORKING LIKE IT SHOULD, IT WILL NOT ARC ANYWHERE TO ANYTHING.
As far as your explanation of the spark will always jump to ground - yes, IF the insulation isn't good enough. But as it's designed, it's more than adequate.
The engineers design the insulation in the cap, rotor, even the wire insulation to withstand that 40 KV - actually much more. A very viable test for ignitions is to test that insulation capability - simply by pulling off a plug wire. The coil can go to it's maximum potential - if it shorts internally, like in the coil, inside the cap, or jumps out the side of that plug wire or the coil wire it's a sure sign the insulation is defective - needs fixing or replacing.
An easy way to see if it's shorting, or isn't reaching the correct potential is by letting the open plug wire jump to ground and observing the color and length of the spark. I already told what to look for.
Even one small shorted turn in the coil will drastically change that color - and the performance of the ignition. It's a good viable reliable test.
The wives tale of having an open plug wire will destroy the module is just that, a fantasy. The only way that could damage the module is if the spark was to jump to the module's input, like to the pick-up coil. Possible, but very unlikely if it's all routed with common sense. Whoever installs the system needs to have a little common sense.
The power valve opening or closing. It's spring loaded - may be a rubber spring flap, but nonetheless a spring of sorts.
Except for a slight inaccuracy of hysteresis (TAZ - please explain hysteresis to TR,) opening and closing are the same value, at virtually the same point. If it opens at 6 or below (providing enrichment,) it also closes at 6 or above (eliminating enrichment.)
Look at his post #1 ----- READ IT!
His first sentance ------
""""""vehicle: 88 YJ 4.2 A/T HEI ignition module, ford dist cap, base and rotor, MC2100 from early 80's Ford van(currently the one with the problem)"""""
IT'S AN HEI! Ford never made an HEI - it's a patented copywrited name for the GM High Energy Ignition!
And according to the first sentence he's also using a Ford Cap - so obviously it's not a GM "built-in" coil. If I remember correctly for previous posts, he's using a TFI coil. He also says he's using the Ford cap, base and rotor, that would be the big cap that YOU always recommend.
The big cap and the GM cap have better insulation than the older smaller ones. The terminals are spaced farther apart and they have insulation ridges inside as barriers to increase the insulation (or should.) THEY ARE DESIGNED TO WITHSTAND THE HIGHER VOLTAGES GENERATED BY THE HEI OR TFI SYSTEMS.
Open circuiting - pulling a plug wire - or having one break or come loose IS NOT AN UNCOMMON OCCURRENCE. The coil voltage will go to it's maximum potential - conventional ignitions about 30 KV, HEI and TFI about 40 KV. There are aftermarket coils that advertise more, but they are bullsh--. It's easy to test. Rising to it's fullest is not harmfull at all. IF THE INSULATION OF THE COMPONENTS IS STILL WORKING LIKE IT SHOULD, IT WILL NOT ARC ANYWHERE TO ANYTHING.
As far as your explanation of the spark will always jump to ground - yes, IF the insulation isn't good enough. But as it's designed, it's more than adequate.
The engineers design the insulation in the cap, rotor, even the wire insulation to withstand that 40 KV - actually much more. A very viable test for ignitions is to test that insulation capability - simply by pulling off a plug wire. The coil can go to it's maximum potential - if it shorts internally, like in the coil, inside the cap, or jumps out the side of that plug wire or the coil wire it's a sure sign the insulation is defective - needs fixing or replacing.
An easy way to see if it's shorting, or isn't reaching the correct potential is by letting the open plug wire jump to ground and observing the color and length of the spark. I already told what to look for.
Even one small shorted turn in the coil will drastically change that color - and the performance of the ignition. It's a good viable reliable test.
The wives tale of having an open plug wire will destroy the module is just that, a fantasy. The only way that could damage the module is if the spark was to jump to the module's input, like to the pick-up coil. Possible, but very unlikely if it's all routed with common sense. Whoever installs the system needs to have a little common sense.
The power valve opening or closing. It's spring loaded - may be a rubber spring flap, but nonetheless a spring of sorts.
Except for a slight inaccuracy of hysteresis (TAZ - please explain hysteresis to TR,) opening and closing are the same value, at virtually the same point. If it opens at 6 or below (providing enrichment,) it also closes at 6 or above (eliminating enrichment.)
Last edited by RRich; 07-01-2009 at 05:18 PM.
Journeyman
Join Date: Feb 2004
Location: Arizona
Posts: 155
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Thanked 1 Time in 1 Post
One thing I love about this site is how in depth you guys go into an explination, assuming that the guy(whom you do not know at all) knows at most just the basics. Another thing I love is the almost competitive spirit. I truly believe that both you gents know what you are talking about, much more than I. And I will use a compelation of your knowledge based posts to diagnose the problem.
I've read some of the somewhat older zshooter posts and, although highly appreciate the knowledge sharing, utilise that information a lot less than one of the more famed novelists and vehicle professionals like RRich and TR. Don't flame me for that zshooter, but come on, you just went through similar issues and gained knowledge yourself at that time. In my original reply to all the posts, the one that was lost somehow, I challenged the reply in many places, like TR pointed out. Anyway, I appreciate all replies, truly. I'm good enough to pick out and determine what's right from wrong, for the most part.
Anyway, I checked centrifigual advance, nothing. No vac line connected, the wife got the 6 up to 2k and there was no advance. With vac connected, it traveled, with slow R increase, fairly evenly up to I'd say 26*. My scale ends at 24. I haven't had the chance to disassemble the dist to see what is sticking, disconnected or broken, but hopefully will sometime over the weekend.
An issue I came across while checking the centrifigual advance, with vac line disconnected, was right around 1500RPM. The engine would stumble. By this time, I had set the mixture screws to achieve best mixture, using a vaccuum gauge and propane at idle. So, when the engine stumbled, I shot propane down the carb throat and it evened out. Too lean...Idle mixture screws are are used for just that, Idle...correct me if I'm wrong please. So my original thought was too small of jets. It was getting late at that time so I pulled the plug wires and distributer, just so I could have it ready for inspection when I got to that point. Thinking more about the issue, and reading these posts, I am beginning to believe that it may have been jets because the ported vac line going to the dist that I disconnected to check centrifugal was not plugged. Makes sense, air coming in from a point that does not have a say on the amount of fuel that gets metered with it. "Alien Air". So that issue may be just a cause of operator error on my part, or maybe I'll blame the wife. hehehe. Either way, I'll have to re-check that after I figure out the dist issue. Haven't yet checked spark or voltage at the coil/module.
TR: That picture shows the weights and (basically)limiters, correct? Replacing springs and weights is a means of adjusting how fast/slow, sooner/later the ignition advances, given different variances. If a person were to replace the springs and weights, in a non high performance application, like mine, they would stick with stock weights and springs, right? If so, where would that person find these stock weights and springs, short of a bone yard? Not Napa, Autozone, or Oreillys, the local jeep dealer doesn't have them, nor can they order them. The local ford dealer is in the same boat. They all require the purchase of a new or rebuilt distributor. But, I haven't inspected mine yet so I'm not sure if its broke as of now.
I'm gonna stick with my 7.5 PV for now. PTC is at 10hg. 2 down is 8, so my options are 7.5 or 8.5. I'll probably check out an 8.5 eventually, after I correct the distributor.
BTW, I am currently running the TFI with HEI module set up. It's all wired up as per the directions given, with correct gauge wire and relay.
Let me ask a question about spark, using my simple minded logic to clarify my reasoning. Obviously its pretty important to have spark, otherwise, the proper mix of air/fuel would not ignite...and yes, I know and understand how a diesel engine achieves combustion. We're talking about a gas engine, though. Why is it so important to have a "strong" spark? Will a "weak" spark not be enough to combust the mix? I'm thinking, as long as the spark is enough to create combustion with fuel, the intensity does not make a difference. How would a fuel burn more completely?...longevity, hence the idea behind multi spark discharge. Anyway, a spark occurs within an instance, whether weak or strong. doesn't the fuel ignite either way? And once that fuel is ignited, it completely combusts because of itself combusting, not because a spark was so intense that it scared it into complete combustion. That is what's going through my mind as I search out reasoning as to why I'm looking for a blue spark snapping and popping like a platoon of Marines in Boot Camp performing rifle manual during final drill, which, BTW, is an amazing sight for those of you who haven't experienced it.
Again, I appreciate everything I am getting from you fine gentlemen. Thank you for spending your hard earn time assisting me.
I've read some of the somewhat older zshooter posts and, although highly appreciate the knowledge sharing, utilise that information a lot less than one of the more famed novelists and vehicle professionals like RRich and TR. Don't flame me for that zshooter, but come on, you just went through similar issues and gained knowledge yourself at that time. In my original reply to all the posts, the one that was lost somehow, I challenged the reply in many places, like TR pointed out. Anyway, I appreciate all replies, truly. I'm good enough to pick out and determine what's right from wrong, for the most part.
Anyway, I checked centrifigual advance, nothing. No vac line connected, the wife got the 6 up to 2k and there was no advance. With vac connected, it traveled, with slow R increase, fairly evenly up to I'd say 26*. My scale ends at 24. I haven't had the chance to disassemble the dist to see what is sticking, disconnected or broken, but hopefully will sometime over the weekend.
An issue I came across while checking the centrifigual advance, with vac line disconnected, was right around 1500RPM. The engine would stumble. By this time, I had set the mixture screws to achieve best mixture, using a vaccuum gauge and propane at idle. So, when the engine stumbled, I shot propane down the carb throat and it evened out. Too lean...Idle mixture screws are are used for just that, Idle...correct me if I'm wrong please. So my original thought was too small of jets. It was getting late at that time so I pulled the plug wires and distributer, just so I could have it ready for inspection when I got to that point. Thinking more about the issue, and reading these posts, I am beginning to believe that it may have been jets because the ported vac line going to the dist that I disconnected to check centrifugal was not plugged. Makes sense, air coming in from a point that does not have a say on the amount of fuel that gets metered with it. "Alien Air". So that issue may be just a cause of operator error on my part, or maybe I'll blame the wife. hehehe. Either way, I'll have to re-check that after I figure out the dist issue. Haven't yet checked spark or voltage at the coil/module.
TR: That picture shows the weights and (basically)limiters, correct? Replacing springs and weights is a means of adjusting how fast/slow, sooner/later the ignition advances, given different variances. If a person were to replace the springs and weights, in a non high performance application, like mine, they would stick with stock weights and springs, right? If so, where would that person find these stock weights and springs, short of a bone yard? Not Napa, Autozone, or Oreillys, the local jeep dealer doesn't have them, nor can they order them. The local ford dealer is in the same boat. They all require the purchase of a new or rebuilt distributor. But, I haven't inspected mine yet so I'm not sure if its broke as of now.
I'm gonna stick with my 7.5 PV for now. PTC is at 10hg. 2 down is 8, so my options are 7.5 or 8.5. I'll probably check out an 8.5 eventually, after I correct the distributor.
BTW, I am currently running the TFI with HEI module set up. It's all wired up as per the directions given, with correct gauge wire and relay.
Let me ask a question about spark, using my simple minded logic to clarify my reasoning. Obviously its pretty important to have spark, otherwise, the proper mix of air/fuel would not ignite...and yes, I know and understand how a diesel engine achieves combustion. We're talking about a gas engine, though. Why is it so important to have a "strong" spark? Will a "weak" spark not be enough to combust the mix? I'm thinking, as long as the spark is enough to create combustion with fuel, the intensity does not make a difference. How would a fuel burn more completely?...longevity, hence the idea behind multi spark discharge. Anyway, a spark occurs within an instance, whether weak or strong. doesn't the fuel ignite either way? And once that fuel is ignited, it completely combusts because of itself combusting, not because a spark was so intense that it scared it into complete combustion. That is what's going through my mind as I search out reasoning as to why I'm looking for a blue spark snapping and popping like a platoon of Marines in Boot Camp performing rifle manual during final drill, which, BTW, is an amazing sight for those of you who haven't experienced it.
Again, I appreciate everything I am getting from you fine gentlemen. Thank you for spending your hard earn time assisting me.
'88 YJ
Journeyman
Join Date: Feb 2004
Location: Arizona
Posts: 155
Thanks: 0
Thanked 1 Time in 1 Post
Wow, that was a long reply. I apologize.
'88 YJ
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