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my 67 with 289 engine shakes when revving. it shakes the whole car when it does this. (see attached video) i didnt notice it before. is this normal? it also started stalling while driving. i'm not sure if it's related. also the gas pedal would get stuck in down position i used to have to pull it back up slightly with my foot but i have recently applied a temp fix until i wait for my new throttle rod to come. i haven't tested it to see if its that yet. im afraid of getting stuck. could all this be related to the shaking? or is this two different issues?
video:
 

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also the gas pedal would get stuck in down position i used to have to pull it back up slightly with my foot but i have recently applied a temp fix until i wait for my new throttle rod to come.
Check the throttle return spring, you don't really want the throttle stuck open.
 

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Discussion Starter #4
Check the throttle return spring, you don't really want the throttle stuck open.
springs seem fine. there was a lot of play between the pedal rod and throttle rod where the joint connects. needs a new bushing and washer. my main concern right now is the shaking and stalling
 

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Your shaking above idle could be several things: vacuum leak, ignition timing off a little, air/fuel ratio (too rich/lean), a bad spark plug or wire. You will need a timing light (for timing check) and a vacuum gauge (for vacuum issues). And you're correct, that engine miss isn't normal.
 

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SOUNDS like an ignition misfire.... hard to tell but I think I can hear it at idle, as well. Bad plug, plug wire, etc. Would venture a guess that a plug wire is arcing to ground somewhere... Grab a spritz bottle of water, start it up at night, spray down the distributor cap, plug wires, etc., and turn off all the lights.
 

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Greetings, This is my first post on this forum. I was a fleet mechanic for 30-year's. ASE Master tech, Smog License all that wonderful stuff that my job required. Now I'm retired. I've had 15 early mustangs between 1977 and now. I have a '66 GT-350 that has been sitting in the garage since 1984. It would qualify as an actual barn find by now. A '70 Boss 302 "project" car I have a couple '64 Falcon projects. A bunch of flathead ford hot rods projects. Probably a total of 15 vehicles. All Fords except for a couple 1915-1920 Mack trucks I hauled home for yard art. I bought a lot of these projects when they were still reasonably priced and I stashed them away for something to do when I retired. It's pretty hard to work on Fleet vehicles all night long and the want to work on cars at home.

Everything anybody tells you is just a guess including me. Mine are educated guesses but they are still guesses. I don't want to tell somebody to go out and buy a part and then I be wrong. I'd rather tell you how to diagnose it yourself. I'm interested in helping people learn about how there cars work. I'm not interested in solving some guy's problem that just wants somebody to tell him which part he needs to replace. If your not interested in how things work you have no business working on them.

I think its either ignition or fuel. If you had an ignition scope you could see if there was ignition problem. You could cancel cylinders one at a time doing a cylinder defeat test. You can see a lean conditions in the plug firing line, fouled plugs,bad wires all that good stuff. Those old Sun ignition scopes are cheap to buy. None of the new shops have a use for them. The problem with them is they take up a lot of room. I bought one cheap, $100.00 and it works perfect. The same Sun scope we used at work for 30-year's. The only problem with them is there are no parts if they die. You are at a big a disadvantage working at home without all these tools and when you are first learning about automobiles its a lot to take in. The good thing is there no simpler car to learn on than a Mustang or a Falcon. They are about as basic as a car gets. I think they are even easier to work on than my early Fords with the flatheads. They are the perfect car to learn on.

Before you do anything I would check the firing order to make sure you do not have two plug wires mixed up. Your engine runs like an engine with two mixed up wires. It will idle decent with a couple of wires mixed but as soon as you bring the rpm up it run like yours running.


There is a sequence that must be followed when tuning up an engine.

With a points ignition you always set the point gap (dwell) first. That is because dwell changes your timing but timing does not change your dwell. Dwell is always checked first. Make sure the points are not pitted and the gap is correct. If you replace them use a good brand name like Standard blue streak points. You should have a dwell meter to verify that you have the correct point gap but feeler gauges work just fine.

Next you set your base timing with a light. Not by ear, not using a vacuum gauge, only with a timing light. You have to hope the marks on your harmonic balancer have not slipped. It would have been really nice if the factory could have marked the inner and outer harmonic balancer pieces so you could tell if they had slipped. Just a couple timing mark dots on each half would have been great.

Next you need to make sure the distributor advance is working. Both the mechanical part and the vacuum part. A nice tool to have is a handheld vacuum pump. You can hook it to the vacuum advance, apply some vacuum and see if the diaphragm holds vacuum and that it is advancing the timing. While you have vacuum advance unhooked if you rev the engine the centrifugal weights inside the distributor should also advance the timing. With an a adjustable timing light you can measure the amount of advance and compare it to the specifications. Do not buy a timing light unless it has the feature to read the advance. I bought a really nice one, new in the box, at an estate sale for $20.00

The very last thing you adjust is the idle air fuel ratio and idle speed screw That is because anything you do that changes the ignition timing will have an an effect on the air fuel ratio. But the air fuel ratio has no effect on the ignition timing. I use a propane enrichment bottle to adjust the air fuel ratio.

If all that checked out above and none of it solved your problem we can continue diagnosing.

A vacuum, gauge is a wonderful tool and easy to use. It can tell you if you have weak piston rings, burned valves, bad valve springs. It is one of the best diagnostic tools, even on modern engines.


Bad motor mounts would not make it misfire but it would definitely cause a vibration. It just takes a little metal to metal contact in the mounts for you to feel it vibrate throughout the car. Its different feeling than a misfire. If you put it in gear, foot on the brake, parking brake set (it really takes two people to do this and don't stand in front of the car with your angry wife behind the wheel) Give it some gas and if it has a broken mount that engine will lift right up on one side and then clunk when it falls back down.

If it was fuel related, most likely a lean condition (plug jets, low float level) it might also backfire back up through the carburetor. Backfiring through the carb is a sign of a lean condition or your timing is way off. If you hold the throttle open like you did in the video until the engine is misfiring you can add propane or starting fluid into the carb and see if the engines smooths out, If it does you have a fuel problem. If not its probably ignition and hopefully not something mechanical.

A vacuum leak would would only cause it to run rough at idle but it would have very little effect on the engine at higher rpms. If you suspect a vacuum leak you can use a propane bottle to look for it. When the leak sucks the propane in the idle will smooth out. You ca have a malfunctioning PCV valve cause it to run lean. That is a maintenance item that needs to be changed according to the service specifications for your engine. Thy never get changed and they should be. I don't think a vacuum leak is your problem

Without scope you need to narrow the problem down to something either effecting all of the cylinders or just a single cylinder. Hold the throttle to that same position you showed in the video and one at a time pull off a spark plug wires and you better have some good insulated pliers or gloves or you are going to get bit hard even if you grab the wire far away from the end your going to get bit and it going to feel like a sledge hammer to your chest. The best thing is to pull all the wires ahead of time and then set them back on so they make contact with the plug but are not clipped on. That way it is easy to remove them. If its a good cylinder, doing its share of the work, the rpm will drop when you remove the plug wire. If there is no drop in rpm or very little drop that cylinder is not producing power. It could be ignition or it could be mechanical problem. Do not pull plug wires off of a running engine with electronic ignition. It can damage the ignition module or computer.
 

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Discussion Starter #9
make sure your harmonic balancer did not slip, check that all your plug wires are on
Greetings, This is my first post on this forum. I was a fleet mechanic for 30-year's. ASE Master tech, Smog License all that wonderful stuff that my job required. Now I'm retired. I've had 15 early mustangs between 1977 and now. I have a '66 GT-350 that has been sitting in the garage since 1984. It would qualify as an actual barn find by now. A '70 Boss 302 "project" car I have a couple '64 Falcon projects. A bunch of flathead ford hot rods projects. Probably a total of 15 vehicles. All Fords except for a couple 1915-1920 Mack trucks I hauled home for yard art. I bought a lot of these projects when they were still reasonably priced and I stashed them away for something to do when I retired. It's pretty hard to work on Fleet vehicles all night long and the want to work on cars at home.

Everything anybody tells you is just a guess including me. Mine are educated guesses but they are still guesses. I don't want to tell somebody to go out and buy a part and then I be wrong. I'd rather tell you how to diagnose it yourself. I'm interested in helping people learn about how there cars work. I'm not interested in solving some guy's problem that just wants somebody to tell him which part he needs to replace. If your not interested in how things work you have no business working on them.

I think its either ignition or fuel. If you had an ignition scope you could see if there was ignition problem. You could cancel cylinders one at a time doing a cylinder defeat test. You can see a lean conditions in the plug firing line, fouled plugs,bad wires all that good stuff. Those old Sun ignition scopes are cheap to buy. None of the new shops have a use for them. The problem with them is they take up a lot of room. I bought one cheap, $100.00 and it works perfect. The same Sun scope we used at work for 30-year's. The only problem with them is there are no parts if they die. You are at a big a disadvantage working at home without all these tools and when you are first learning about automobiles its a lot to take in. The good thing is there no simpler car to learn on than a Mustang or a Falcon. They are about as basic as a car gets. I think they are even easier to work on than my early Fords with the flatheads. They are the perfect car to learn on.

Before you do anything I would check the firing order to make sure you do not have two plug wires mixed up. Your engine runs like an engine with two mixed up wires. It will idle decent with a couple of wires mixed but as soon as you bring the rpm up it run like yours running.


There is a sequence that must be followed when tuning up an engine.

With a points ignition you always set the point gap (dwell) first. That is because dwell changes your timing but timing does not change your dwell. Dwell is always checked first. Make sure the points are not pitted and the gap is correct. If you replace them use a good brand name like Standard blue streak points. You should have a dwell meter to verify that you have the correct point gap but feeler gauges work just fine.

Next you set your base timing with a light. Not by ear, not using a vacuum gauge, only with a timing light. You have to hope the marks on your harmonic balancer have not slipped. It would have been really nice if the factory could have marked the inner and outer harmonic balancer pieces so you could tell if they had slipped. Just a couple timing mark dots on each half would have been great.

Next you need to make sure the distributor advance is working. Both the mechanical part and the vacuum part. A nice tool to have is a handheld vacuum pump. You can hook it to the vacuum advance, apply some vacuum and see if the diaphragm holds vacuum and that it is advancing the timing. While you have vacuum advance unhooked if you rev the engine the centrifugal weights inside the distributor should also advance the timing. With an a adjustable timing light you can measure the amount of advance and compare it to the specifications. Do not buy a timing light unless it has the feature to read the advance. I bought a really nice one, new in the box, at an estate sale for $20.00

The very last thing you adjust is the idle air fuel ratio and idle speed screw That is because anything you do that changes the ignition timing will have an an effect on the air fuel ratio. But the air fuel ratio has no effect on the ignition timing. I use a propane enrichment bottle to adjust the air fuel ratio.

If all that checked out above and none of it solved your problem we can continue diagnosing.

A vacuum, gauge is a wonderful tool and easy to use. It can tell you if you have weak piston rings, burned valves, bad valve springs. It is one of the best diagnostic tools, even on modern engines.


Bad motor mounts would not make it misfire but it would definitely cause a vibration. It just takes a little metal to metal contact in the mounts for you to feel it vibrate throughout the car. Its different feeling than a misfire. If you put it in gear, foot on the brake, parking brake set (it really takes two people to do this and don't stand in front of the car with your angry wife behind the wheel) Give it some gas and if it has a broken mount that engine will lift right up on one side and then clunk when it falls back down.

If it was fuel related, most likely a lean condition (plug jets, low float level) it might also backfire back up through the carburetor. Backfiring through the carb is a sign of a lean condition or your timing is way off. If you hold the throttle open like you did in the video until the engine is misfiring you can add propane or starting fluid into the carb and see if the engines smooths out, If it does you have a fuel problem. If not its probably ignition and hopefully not something mechanical.

A vacuum leak would would only cause it to run rough at idle but it would have very little effect on the engine at higher rpms. If you suspect a vacuum leak you can use a propane bottle to look for it. When the leak sucks the propane in the idle will smooth out. You ca have a malfunctioning PCV valve cause it to run lean. That is a maintenance item that needs to be changed according to the service specifications for your engine. Thy never get changed and they should be. I don't think a vacuum leak is your problem

Without scope you need to narrow the problem down to something either effecting all of the cylinders or just a single cylinder. Hold the throttle to that same position you showed in the video and one at a time pull off a spark plug wires and you better have some good insulated pliers or gloves or you are going to get bit hard even if you grab the wire far away from the end your going to get bit and it going to feel like a sledge hammer to your chest. The best thing is to pull all the wires ahead of time and then set them back on so they make contact with the plug but are not clipped on. That way it is easy to remove them. If its a good cylinder, doing its share of the work, the rpm will drop when you remove the plug wire. If there is no drop in rpm or very little drop that cylinder is not producing power. It could be ignition or it could be mechanical problem. Do not pull plug wires off of a running engine with electronic ignition. It can damage the ignition module or computer.
i'm too much of a beginner to understand all of that. but very interesting for sure and thank you for your response! i'll probably just replace all the plugs and wires and see if that fixes it and go from there. i recently replaced the pcv valve and hose but i didn't notice this problem right away after that unless i missed it. could this be linked to the stalling while driving? the engine would just cut out while cruising. loss of throttle and power steering. but would start right up after turn key. i fixed my pedal problem and took it for a spin today and didn't stall. i don't notice the shaking while driving on the road. only when i rev the engine while in park.
 

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Discussion Starter #10
so i replaced the coil today because that was the first part to arrive and it shakes even worse now. i can never catch a break.
 

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That test will show a faulty distributor cap as well. If you're throwing parts at it, throw a cap and rotor as well.
 

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Before you do Bartl's test, which is a great place to start, please make sure there are no fuel leaks anywhere.
 

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If you have not checked the firing order of those plug wires like I suggested and you replace them with new wires you might still have two wires mixed up. You need to check this.
 

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they are the right order
Hi Scott,
Hard to tell from the video, but it looks like you are running the HO firing order (13726548)..?

Not sure what's been done to your engine(cam?) but should you be running the standard order? (15426378)

Sent from my SM-G950F using Tapatalk
 

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Discussion Starter #19
i just replaced all the plugs and wires. made sure the gaps were correct, and in the right order (15426378 i also followed a diagram to make sure). and the thing still shakes. about the same as before. when i replaced it with a new coil it was worse. so im assuming my old coil is good. faster rpm i dont notice any shaking. seems when its revved at a slower rpm is when it really bugs out. there is a slight ticking sound but im not sure if its coming from the plugs or my belts. im new to this car stuff. so i'm stumped. i really dont want to keep paying a shop to fix this car for me. i got it so i could have a cool mustang to drive and learn some stuff along the way while saving money on doing the work on my own.
 

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Distributor cap and rotor, points and condenser, Are service parts and should be replaced when unsure of its service history.
Does it have points? Correct coil for your ignition type?
 
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