Burned points on distrobitor cap.

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2/3 of copper point seem to be a bit burned on the cap. Should I assume cap was crooked?

Flamethrower with Ignator 3 ignition coil.
Insulated by the last owner in 2013, but had maybe 5 -10k miles since.
 

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It's a 73 mustang.
Bought the car few weeks ago as is and looked into this today.

Runs rought at idle (likes to die when cold), chokes and at times stals when starting to accelerate from the dead stop (auto). Engine runs fairly smooth while driving.

Lookes like it has Petronix Flamethrower with Igniter 3, while rest of the ignition seems to be stock.
 
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We need more, how old, symptoms of the engine, etc
Looks like it was installed in 2013 (based on the date on the box), but had no more then 5k mile since.
 

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piper62j

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It appears that the secondary voltage must be higher to fire the plugs on the side of the distributor contacts which are worn.. The voltage produced by the coil remains constant unless there is interference down the line to increase the amount of voltage needed to fire the plug. These issues could be related to incorrect spark plug heat range, fouled plugs, high spark plug wire resistance, unbalanced compression between cylinders or incorrect cam lift to those affected cylinders creating an unbalanced rich or lean mixture. It's worth taking the time for diagnosing before replacing parts. The distributor cap and rotor should be replaced.
 
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It appears that the secondary voltage must be higher to fire the plugs on the side of the distributor contacts which are worn.. The voltage produced by the coil remains constant unless there is interference down the line to increase the amount of voltage needed to fire the plug. These issues could be related to incorrect spark plug heat range, fouled plugs, high spark plug wire resistance, unbalanced compression between cylinders or incorrect cam lift to those affected cylinders creating an unbalanced rich or lean mixture. It's worth taking the time for diagnosing before replacing parts. The distributor cap and rotor should be replaced.
Thanks for replying.
I will test compression next (block was never refreshed).

Spark plug wire resistance measures between 1300 and 1500 Ohms. Do you think its high for ignitor 3 system?
 
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I've had a bad experience with an Ignitor III, but that was installed in a stock Autolite distributor. I see you have a Pertronix dizzy, so may not be the same or similar issue. Check the top distributor plate for movement sideways and up and down. It is possible the "bearing" between the top and bottom plates is worn, allowing the "air gap" to change. That may result in the rough idle and burned contacts.
As said, installed in a Pertronix distributor, this may not be the case, but worth checking.
Added jpg of Ignitor III instructions and a pic of a III for stock distributor. Not sure if that helps.
 

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The plugs being loose enough to remove with using a socket tells me they were likely not grounded properly, which would have demanded more voltage to jump the spark plug gap. Also, the specs call for a spark plug gap of either 0.034" to 0.035" (varies, your spec is apparently 0.036"). When gapped wider, the voltage required to jump the gap will be higher than "normal" also. I do not recall what the nominal resistance per foot is for secondary spark plug cables. For me, rather than looking at the results of running the way things were set up, and guessing at the running voltage of the secondary ignition system, I would be looking for someone (like us) that has an old school Sun Oscilloscope so the secondary ignition firing patterns can be looked at to see exactly what voltage is used to initially jump the plug gaps, see what the arc sustained voltage is, then see if the collapsing voltage pattern looks like. I would also be checking the maximum coil output voltage, just to make sure there is enough voltage to jump the plug gaps and overcome any resistance in the secondary circuit paths. I am a big fan of modern electronic control of the engines, and the memory capability that stores Diagnostic Trouble Codes. But, we did not have that back in the olden days with old school electro-mechanical ignition systems. Those Sun oscilloscopes are wonderful tools, in the right hands, to look at an old school ignition system giving trouble, and ascertaining what the cause(s) of the trouble might be.

The spark plug you show in the post above my comment looks like it is firing properly, has a good combustion burn, and the electrodes are not burned off to a rounded or pitted edge condition. The slightly darker brown color on the center insulator is not anything I would worry about, as it is there due to that side of the insulator's exposure to the flame front of the burning gas in the combustion chamber. There is no excessively white insulator (indicates a too lean Air/Fuel mixture), and no black soot (indicates excessively rich Air/Fuel mixture), and no indication of excessive oil being burned in the combustion chamber. But, I can't tell the gap from the photo. If a plug's gap was too small (0.032" for instance), an engine will tend to run rough, allegedly due to the spark not being "large" enough to effect a good burn of the combustible Air/Fuel mixture. If it was gapped too large (0.040") it might idle smoothly, but at higher RPM there could be a misfire, allegedly due to higher combustion pressure that prevents the plug gap from being able to allow a spark to go across it. That lack of spark at the plug's gap was sometimes due to the high voltage in the secondary ignition system finding an easier place to arc to ground, leaving not enough remaining current/voltage to jump the spark plug's gap (it already shot its wad).

Often, with older oem, graphite core plug wires, the high voltage would arc to ground through failing insulation, especially at places where the insulation was exposed to too much heat where it would begin to become brittle. One way I use to be able to demonstrate the effect of insulation that was breaking down was by raising the hood at night when it was dark while an engine was running. It was amazing the kind of light show one could see with arcing voltage here and there with compromised insulation, often arcing to ground improperly inconsistently. But an external arc means that current never made it to the spark plug - hence a misfire resulted. Other areas where high voltage would arc to ground, other than at a plug gap, would be to follow a crack or residue/dirt in the plug's external insulator (or dirt inside a plug wire's "boot"), across a crack or carbon track inside the distributor cap (not likely on a new cap like yours), and once I even found the rotor inside a distributor cap was burned through at the center, so the voltage from the coil would ground through the distributor shaft - intermittently. With weak insulation, having spark plug wires running too close to each other, in parallel, would allegedly allow the current in one wire to transcend to the other cable laying too close to it. I never saw that myself, but I know it was a concern, especially when using a copper core ignition wire (I do not recommend copper core ignition wires, (BTW).

Anyway, the arcing indication I see on the rotor's tip, and some of the distributor cap's electrodes, especially considering those were new(er) parts, indicates a very high voltage is being required to fire the plugs - which could be from a combination of too large a plug gap, loose plugs providing a poor ground, and/or inadequate resistance of the ignition cables (depending on what the resistance specs are for graphite core cables). If only some of the plugs were loose, and others were fairly tight, that could account for the varying arc burn conditions you found with different cap electrodes. If you were closer to us (Rochester, NY) I would be happy to set you up on our Sun scope and see exactly what your ignition system is doing. That you already re-gapped the plugs, and reinstalled the plugs with the proper torque (not left loose) may have already corrected the bigger causes of issues. Thus, you may be in pretty good shape now, electrically.

As an aside, no matter what your ignition coil's maximum voltage is, the voltage it produces will never exceed the voltage required to get the high voltage current to reach ground. If you have a maximum 50,000 volt output, if all it takes is 35,000 volts to jump the plug gap, that is the most the coil will output. Thus, I do not put a lot of stock in ignition systems that claim to have extremely high voltage output. Rather, I preferred to focus on not exceeding a certain level of initial gap jumping voltage per the oscilloscope, where that required initial gap jumping voltage was appropriately lower than a coil's maximum output level. I also preferred to provide plenty of coil saturation with the primary ignition circuit by keeping the dwell angle at the wider end of spec (usually we have range of say 26 degrees to 31 degrees). That allows the primary ignition side of the ignition system plenty of opportunity to let the coil build up a nice, fat amount of electrical pressure at higher RPMs.

Although I happen to like Pertronix and other electronic retrofit kits, personally, unless you are tracking/racing your car, the old school electro-mechanical ignition systems are fine. If you are running significantly higher than normal RPMs, the electronic ignition systems may do some good, assuming the distributor is in good working order (no excessive wear with the distributor shaft bushings, breaker plate is not badly worn, no excessive engine blowby gas getting inside the distributor cap, etc.). As long as you are using a good aftermarket electronic ignition solution they will not hurt. But, you need to be careful to get the correct voltage to the "correct" style ignition coil. Some coils are designed to run at full battery voltage. Running full battery voltage to a running engine with an oem coil designed to run at 9-10 voltage will cause the coil to overheat and fail earlier than normal. But, not getting full battery voltage to an aftermarket coil designed for 12-13 volts can lead to inadequate secondary voltage - which leads to plug misfire. I have seen some aftermarket systems that can be used with the oem ignition coils, and other kits that highly recommend using their higher primary voltage ignition coils. Follow the ignition kit manufacturer's recommendations. If you need to provide full battery voltage to an ignition coil there are several ways you can accomplish that. One way is to run a non-resistance wire from the ignition switch to the ignition coil, bypassing the factory resistance wire (that is a real PITA to so). The other way is to tap into a switched 12 volt circuit normally used to power some other device. For First Generation Mustangs that can be done by tapping into the wiper motor's Red wire (Circuit #63). The draw on that circuit with the wipers running ought to be low enough to still let enough voltage get to the coil with the engine running, and the added current demand with the coil ought to be low enough to not cause a problem with any fuses or circuit breakers for Circuit #63. For 71-73 Mustangs there is a Red wire with Yellow Hash markers that powers a Throttle Position Solenoid (TPS). Not all engines had a TPS in 71-73, but the wiring harness still has the lead for a TPS. That is another great place to grab full battery voltage at. I have some folks tap the "I" terminal of the Start Relay to feel the coil - but that is because they do not understand how that circuit (#32) works - so do not do that, you will not get the results you seek. Also, for 1973 engines with electric chokes, do NOT tap into the White wire with a Black stripe (Circuit #4), as it is powered by the alternator's Stator terminal, which is 1/2 alternator output voltage and Alternating Current (AC), as opposed to Direct Current (DC). Here are some YouTube videos that may help with the 12 volt switch circuit:






More in the post below...
 

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Continued from prior post, 1,000 character limit per post)

I know that is a lot of information I just threw at you in the post above. I almost feel I should be apologizing to anyone who has taken the time to read it to this point. But, there is a little more I feel I ought to be sharing with you. So here goes... When you crank an engine over the Starter Relay's "I" terminal is used to send "full battery voltage" to the positive primary circuit terminal of the ignition coil. Often, too often, I hear folks say that is how you get a "full 12 volts" sent to the coil during cranking in order to provide a hotter spark to start the engine. Nope, that is not how it works. First of all, with an ignition system in good working order there is no need for a "hotter spark," and for that matter, a higher potential voltage from the coil does not mean it will necessarily output a "hotter spark." As I mentioned above, the coil will only output what is needed to get its current to ground, and hopefully that is done at the spark plug gaps. Here is what is really happening. The way I stated it is correct, the Starter Relay sends "full battery voltage" to the ignition coil's positive primary circuit terminal while the engine is being cranked over. BUT... when the engine is being cranked over the battery's voltage drops to about 9.6 - 10.5 volts or so. Thus, the ignition coil is only getting that much voltage sent to it (9.6 - 10.5 volts). When the ignition key is released and returns to its Run position, the resistor wire sends a reduced voltage to the ignition coil (about 10 volts more or less). The flip side is that when you replace the oem coil with one that requires 12 volts to run, you may be giving it 12 - 13 volts while the engine is running, but when the engine is cranking the most it will get is about 9.6 - 10.5 volts, meaning during cranking there is less potential output from the ignition coil - but that is still enough to send an adequate spark across a plug gap to start the engine. So, I guess the point is what you have likely been hearing about the cranking voltage to the coil being 12 volts is wrong, and the need for a higher voltage during cranking is also apparently wrong. Just something to ponder now that you have been told. We all have to be careful what we choose to believe, especially when it comes to how electrical systems behave.

I wish I knew someone in your area who has an oscilloscope and knows how to use it. I do know a former Sun rep, who has been working with other former Sun reps across the nation, who rebuilds, repairs, and uses these old school scopes. I you do not know where you can go to have your engine's ignition system scoped and checked for proper operation, let me know (email me at [email protected]) and I will ask him who he knows in your area who has a scope. If he does not know, he will know someone who does. Or, better yet, plan a road trip out to our place (Pittsford, NY, near Rochester) and I will scope your system. Free. Plus, we have a guest house (Casa De Shelby) you can stay at (also free). While you are out here, if you have not seen the Niagara Falls, this is your chance, as we are just about an hour away from there. Let me know. If nothing else you can see one of your cousin or sister cars (we have a 73 Mach 1 and a 73 vert) while out here.
 
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It's a 73 mustang.
Bought the car few weeks ago as is and looked into this today.

Runs rought at idle (likes to die when cold), chokes and at times stals when starting to accelerate from the dead stop (auto). Engine runs fairly smooth while driving.

Lookes like it has Petronix Flamethrower with Igniter 3, while rest of the ignition seems to be stock.
Yeah, I have more to share with you, re: the "Runs rough at idle (likes to die when cold), chokes and at times stalls when starting to accelerate from the dead stop (auto). Engine runs fairly smooth while driving." The runs rough at idle and the choking and stalling when accelerating condition tells me you are running into a carburetor issue, or at least something that is causing you to run a bit lean when you need a richer Air/Fuel ratio (cold engine). From your member info I see you are running a 2v carburetor, and I am assuming it is an Autolite 2100. If so, that is a good thing as they are simple to work on, fairly easy to adjust, and also easy to rebuild when needed. We also have a 2100 on our 73 Mustang Convertible's 302 engine, and I had to work on it recently, as it was causing a slight hesitation on light acceleration. Before I tore into the carburetor I first disconnected the vacuum line to the EGR valve (temporarily, it was connected again) to make sure the EGR valve opening off idle was not causing the hesitation - the condition remained unchanged, so it was not the EGR valve causing the problem. With the air cleaner off I watched down the venturi throats as I opened the throttle to make certain the accelerator pump was sending "adequate" fuel out the acceleration pump discharge nozzles. That also looked good.

A quick aside, I purposely said "sending 'adequate' fuel out the ... discharge nozzles" for a reason. Story time... Years ago, working as a tech at a Lincoln dealership, a customer with a new Mercury Monarch (Ford Granada) came in saying he had a hesitation on acceleration. I took the car out and he was right, but it was not as bad as most cars when an accelerator pump was having problems. I suspected the EGR valve, but as with our car unplugging it (temporarily) did not help. When I looked down the venturis and opened the throttle only one discharge nozzle was squirting fuel in an amount I was expecting. The other was dribbling (on a new car). I took the accelerator pump and fuel pickup assembly off and found some brass cuttings stuck in the one discharge nozzle(!). The customer was a young guy who was obviously tasting success in his business, so I told him what I found, and if he wanted I could make extra sure he had decent acceleration beyond just removing the machine cutting out of the nozzle, but it may cause his fuel mileage to drop a little - hardly noticeable. He was all for more pep, so I used a jeweler's drill bit and hand vise, and not only cleared the one accelerator brass outlet from the one nozzle, but I used a slightly larger drill bit to make both nozzles just a very tiny bit larger in diameter - it does not take much to effect a change in performance). I went out on a test drive, with him, after wrapping it up. Wow! He was impressed, especially once I changed places with him and let him drive us back to the dealership. Ever since then I have made it a habit of looking at the accelerator pump fuel discharge whenever I had a car come in, complaint or not.

Anyway, back to our 2100 project... With the accelerator pump looking like it was working good, the EGR not causing the hesitation, and the distributor vacuum advance system working properly, I felt the only other two possibilities were the air breaks for the venturi fuel pickup tubes were plugged (very unlikely), or the fuel float level in the fuel bowl was too low. Well, here is "the twist" in this situation...

This particular vert was literally barn stored over 30 years, after the 2nd owner had gotten very ill, and later passed away. He had purchased the vert when it was virtually new, as the original owner traded it in for a 4x4 when he retired soon after buying the vert. The 3rd owner, a Mustang enthusiast, came across it many years later, in a barn, and purchased it. At the time the Mustang only had about 13,000 original miles on it (circa 2007). When we purchased it in mid 2019 it only had just over 19,000 original miles on it (see attached image file)! The engine had been running well when we first got it, and later when the hesitation became evident I did not feel enough time had passed to have the air breaks in the venturi fuel pickup tubes to get plugged - but it was a lot of years. But, it also seems unlikely the float level would have been too low for what was essentially an almost new car, hardly used. No matter, the carb was coming off.

Upon removing the carb I noted the passenger front mounting nut was finger tight, at best. The other three nuts felt tight as I removed them. I looked at the gasket between the base of the carb, and the intake manifold. It was an extra thick gasket that was intended to prevent too much engine heat from getting to the carburetor fuel bowl and boil the fuel. The part of the gasket nearest the loose nut never crimped properly, so that meant we had at least a nominal vacuum leak. Enough to cause the idle mixture adjustment screws to have been run out by 4 turns, more than I would have expected (usually 2 3/4 - 3 1/4 turns). But, not enough of a leak to explain the hesitation. The air breaks for the venturi pickup fuel tubes were not plugged, the air inlet and venturi clusters looked very clean - what I would have expected for a fairly low mileage engine and carburetor. I then removed the top cover, and pressed on the fuel float tang over the fuel needle/valve inlet. Ah ha! I found the problem. The float was set about 1/4" too low, may be more. But, how? Why? It was not likely it came that way from the factory, and I had rebuilt enough of those 2100s back "in the day" to know their float levels were pretty much dead on from the factory. Then, I figured it must have been rebuilt for some reason, most likely a leaking or ruptured Power Valve, and the float was adjusted too low - maybe by accident, maybe "on purpose." But, why would anyone set it too low? Well, back "in the day" there were some folks who intentionally set fuel float levels a little on the low side to allegedly get better fuel mileage as it causes the carb to produce a leaner Air/Fuel ratio. But, this was lower than that kind of malarky. No matter...

I went ahead and rebuilt the carburetor, and found the Power Valve had been double gasketed. Definitely "someone" had it apart previously, and whoever it was used two gaskets (often two gaskets of slightly different shapes are provided in the rebuild kits) instead of just choosing the one that best fit where the Power Valve fuel channels were located (often two gaskets of slightly different shape are provided in the rebuild kits). So I installed the new Power Valve, using only one gasket, cleaned out the various air and fuel channels, replaced the fuel inlet needle and seat, and adjusted the float to its proper level (after shaking it to see if any fuel was leaking into it - brass float). After I reassembled the carb, it fired up immediately, and only required me to lean out the idle mixture screws a little bit, now that the base plate vacuum leak was fixed when I properly tightened down all for mounting nuts. On the test drive, the carburetor performed perfectly, the hesitation upon acceleration (light or heavy) was gone.

I (of course) had Lynda do a video recording of the carb rebuild and adjustment processes. It is a long video (over 3 hours), but if you have never rebuilt a 2100 before I think you will find some good info in it. You can fast forward past any boring parts if you like. I also have two other related videos. One shows how to adjust the cold high idle speed cam and screw, the Throttle Position Solenoid (TPS), the idle Air/Fuel mixture screws, and the Base Idle speed (TPS off) setting. Another shows how I corrected a fuel leak where the fuel filter is screwed into the carb housing, as "someone" previously screwed the filter in far too deeply, which caused me to have to deal with a fuel leak.

I hope you find the videos useful. I do feel your hesitation is due to an accelerator pump or related issue, but without seeing the car it is hard to tell for sure. But, the only other thing (besides an EGR valve that open too aggressively, or a too low fuel float level) that can cause a hesitation on acceleration is a ruptured or leaking distributor vacuum advance diaphragm, and that causes more of a sluggish performance issue on acceleration than a true carburetor induced hesitation or "bog." And, of course, I have some videos that show how to test a distributor vacuum advance diaphragm, and how to to test to make certain ported vacuum is making it to the diaphragm to begin with. You may need to skip around a it to find the vacuum advance diaphragm and ported vacuum testing parts, as I cover a few things in the following videos. But, if you end up watching more than what you need you may just learn something else that will help you someday.









I hope all that helps you with the hesitation issue you are having.
 

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piper62j

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Yeah, I have more to share with you, re: the "Runs rough at idle (likes to die when cold), chokes and at times stalls when starting to accelerate from the dead stop (auto). Engine runs fairly smooth while driving." The runs rough at idle and the choking and stalling when accelerating condition tells me you are running into a carburetor issue, or at least something that is causing you to run a bit lean when you need a richer Air/Fuel ratio (cold engine). From your member info I see you are running a 2v carburetor, and I am assuming it is an Autolite 2100. If so, that is a good thing as they are simple to work on, fairly easy to adjust, and also easy to rebuild when needed. We also have a 2100 on our 73 Mustang Convertible's 302 engine, and I had to work on it recently, as it was causing a slight hesitation on light acceleration. Before I tore into the carburetor I first disconnected the vacuum line to the EGR valve (temporarily, it was connected again) to make sure the EGR valve opening off idle was not causing the hesitation - the condition remained unchanged, so it was not the EGR valve causing the problem. With the air cleaner off I watched down the venturi throats as I opened the throttle to make certain the accelerator pump was sending "adequate" fuel out the acceleration pump discharge nozzles. That also looked good.

A quick aside, I purposely said "sending 'adequate' fuel out the ... discharge nozzles" for a reason. Story time... Years ago, working as a tech at a Lincoln dealership, a customer with a new Mercury Monarch (Ford Granada) came in saying he had a hesitation on acceleration. I took the car out and he was right, but it was not as bad as most cars when an accelerator pump was having problems. I suspected the EGR valve, but as with our car unplugging it (temporarily) did not help. When I looked down the venturis and opened the throttle only one discharge nozzle was squirting fuel in an amount I was expecting. The other was dribbling (on a new car). I took the accelerator pump and fuel pickup assembly off and found some brass cuttings stuck in the one discharge nozzle(!). The customer was a young guy who was obviously tasting success in his business, so I told him what I found, and if he wanted I could make extra sure he had decent acceleration beyond just removing the machine cutting out of the nozzle, but it may cause his fuel mileage to drop a little - hardly noticeable. He was all for more pep, so I used a jeweler's drill bit and hand vise, and not only cleared the one accelerator brass outlet from the one nozzle, but I used a slightly larger drill bit to make both nozzles just a very tiny bit larger in diameter - it does not take much to effect a change in performance). I went out on a test drive, with him, after wrapping it up. Wow! He was impressed, especially once I changed places with him and let him drive us back to the dealership. Ever since then I have made it a habit of looking at the accelerator pump fuel discharge whenever I had a car come in, complaint or not.

Anyway, back to our 2100 project... With the accelerator pump looking like it was working good, the EGR not causing the hesitation, and the distributor vacuum advance system working properly, I felt the only other two possibilities were the air breaks for the venturi fuel pickup tubes were plugged (very unlikely), or the fuel float level in the fuel bowl was too low. Well, here is "the twist" in this situation...

This particular vert was literally barn stored over 30 years, after the 2nd owner had gotten very ill, and later passed away. He had purchased the vert when it was virtually new, as the original owner traded it in for a 4x4 when he retired soon after buying the vert. The 3rd owner, a Mustang enthusiast, came across it many years later, in a barn, and purchased it. At the time the Mustang only had about 13,000 original miles on it (circa 2007). When we purchased it in mid 2019 it only had just over 19,000 original miles on it (see attached image file)! The engine had been running well when we first got it, and later when the hesitation became evident I did not feel enough time had passed to have the air breaks in the venturi fuel pickup tubes to get plugged - but it was a lot of years. But, it also seems unlikely the float level would have been too low for what was essentially an almost new car, hardly used. No matter, the carb was coming off.

Upon removing the carb I noted the passenger front mounting nut was finger tight, at best. The other three nuts felt tight as I removed them. I looked at the gasket between the base of the carb, and the intake manifold. It was an extra thick gasket that was intended to prevent too much engine heat from getting to the carburetor fuel bowl and boil the fuel. The part of the gasket nearest the loose nut never crimped properly, so that meant we had at least a nominal vacuum leak. Enough to cause the idle mixture adjustment screws to have been run out by 4 turns, more than I would have expected (usually 2 3/4 - 3 1/4 turns). But, not enough of a leak to explain the hesitation. The air breaks for the venturi pickup fuel tubes were not plugged, the air inlet and venturi clusters looked very clean - what I would have expected for a fairly low mileage engine and carburetor. I then removed the top cover, and pressed on the fuel float tang over the fuel needle/valve inlet. Ah ha! I found the problem. The float was set about 1/4" too low, may be more. But, how? Why? It was not likely it came that way from the factory, and I had rebuilt enough of those 2100s back "in the day" to know their float levels were pretty much dead on from the factory. Then, I figured it must have been rebuilt for some reason, most likely a leaking or ruptured Power Valve, and the float was adjusted too low - maybe by accident, maybe "on purpose." But, why would anyone set it too low? Well, back "in the day" there were some folks who intentionally set fuel float levels a little on the low side to allegedly get better fuel mileage as it causes the carb to produce a leaner Air/Fuel ratio. But, this was lower than that kind of malarky. No matter...

I went ahead and rebuilt the carburetor, and found the Power Valve had been double gasketed. Definitely "someone" had it apart previously, and whoever it was used two gaskets (often two gaskets of slightly different shapes are provided in the rebuild kits) instead of just choosing the one that best fit where the Power Valve fuel channels were located (often two gaskets of slightly different shape are provided in the rebuild kits). So I installed the new Power Valve, using only one gasket, cleaned out the various air and fuel channels, replaced the fuel inlet needle and seat, and adjusted the float to its proper level (after shaking it to see if any fuel was leaking into it - brass float). After I reassembled the carb, it fired up immediately, and only required me to lean out the idle mixture screws a little bit, now that the base plate vacuum leak was fixed when I properly tightened down all for mounting nuts. On the test drive, the carburetor performed perfectly, the hesitation upon acceleration (light or heavy) was gone.

I (of course) had Lynda do a video recording of the carb rebuild and adjustment processes. It is a long video (over 3 hours), but if you have never rebuilt a 2100 before I think you will find some good info in it. You can fast forward past any boring parts if you like. I also have two other related videos. One shows how to adjust the cold high idle speed cam and screw, the Throttle Position Solenoid (TPS), the idle Air/Fuel mixture screws, and the Base Idle speed (TPS off) setting. Another shows how I corrected a fuel leak where the fuel filter is screwed into the carb housing, as "someone" previously screwed the filter in far too deeply, which caused me to have to deal with a fuel leak.

I hope you find the videos useful. I do feel your hesitation is due to an accelerator pump or related issue, but without seeing the car it is hard to tell for sure. But, the only other thing (besides an EGR valve that open too aggressively, or a too low fuel float level) that can cause a hesitation on acceleration is a ruptured or leaking distributor vacuum advance diaphragm, and that causes more of a sluggish performance issue on acceleration than a true carburetor induced hesitation or "bog." And, of course, I have some videos that show how to test a distributor vacuum advance diaphragm, and how to to test to make certain ported vacuum is making it to the diaphragm to begin with. You may need to skip around a it to find the vacuum advance diaphragm and ported vacuum testing parts, as I cover a few things in the following videos. But, if you end up watching more than what you need you may just learn something else that will help you someday.









I hope all that helps you with the hesitation issue you are having.
 
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Loose plugs may be due to the use of a socket that is just a bit too large in diameter requiring it to be tapered on the open end. I learned this the hard way many years ago. Another source of corrosion inside the distributor is the ozone that is generated when the arc occurs. This is worsened with an unvented cap. The coloring on the plugs looks pretty good, just a tad rich and timing is close to being spot on. Chuck
 
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Thank you for detailed write up.
Car has original carburetor which was rebuilt 10 years ago by the last owner, not a shop (based on paperwork - car came with a book of receipts dating back to mid 70s).

I did not find any trace of 12v wire, bypassing speedo/tech or any non oem splicing under the hood to pull 12v. So ignition is most likely getting 9v - will test with a meter today to be sure. This distributor need 12V.

I gaped spark plugs to .036 because flamethrower with ignitor 3 required larger gap, assuming 12v. Needs to be 0.005 larger then stock. So .036 will be the smallest I can go once I have 12v.

My plan is to wire in 12v bypas as per video below and dive in to carburetor after per your recommendation.



I also purchased 6 volumes of 73 Ford shop manuals to gain better understanding of this retro technology.
 
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Excellent dialog mrgmhale. You are spot on with the info.. Thanks
Thank you, and sorry for the lengthy posts. I could not just provide a "little" info, as there is so much that can underly the kinds of issues being asked about. I just felt he deserved to see what he was getting into potentially. That said, I know it was a lot to read (and write). If I did not think it was useful I would not have taken the time to write all that. I just try to be clear and thorough when communicating with our fellow Mustang/Shelby enthusiasts. Done nearly to a fault, eh?
 
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Thank you, and sorry for the lengthy posts. I could not just provide a "little" info, as there is so much that can underly the kinds of issues being asked about. I just felt he deserved to see what he was getting into potentially. That said, I know it was a lot to read (and write). If I did not think it was useful I would not have taken the time to write all that. I just try to be clear and thorough when communicating with our fellow Mustang/Shelby enthusiasts. Done nearly to a fault, eh?

It's first time for me to have a carburated car. So lots to learn. Up untill now I been only messing around and tuning with cars with OBD2/ecu (installing cams, porting heads and manifolds, ecu programming to some degree).

So far, with just regaping spark plugs, using dielectric grease on boots and (lots of grease) on the main wire leading from the coil, as boot on the coil is cracked and loose on the wire - car start up better and idles better.


Also adjusted idle at cold to 1,000rpms. No staling backing out of garage after 1 min warm up.
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