73 project (advice wanted)

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MMoyer

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Im 16 bought a 73 mustang with the 351c and auto transmission it is now occupying space in my yard. It runs and drives fine except for some electrical and weird tranny issue. my end goal is restomod with 350-400 hp/tq I want to do a lot of the work myself. I dont know any one that i could sit down and talk with about it so i came here. motor is in pretty good shape probably need new tranny and some body work including new floor pan. The first thing I plan on doing is getting a new ignition system (i think its easy enough to do myself) I dont have a whole lot of experience with mechanics so any advice would be greatly appreciated. also I would like to be able to daily drive it after the transmission and wiring are fixed
 
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I wish you were in Texas, I would be more than willing to help you here. What is the weird tranny issue? 350-400 HP out of a 351 C is very doable, but you will need a complete combination to make it work right, the correct converter for the cam you choose, some rear end gears, and a good trac loc differential with at least 3.25 gears, but preferably 3.55's. If the tranny needs a full rebuild, and you are doing a resto mod, you may just look into swapping an AOD or AODE in it...
 
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Welcome from Phoenix. Small upgrades like the ignition are good but before you start buying parts put together a plan for the drive train and then start collecting parts! Don't forget that car parts make great birthday and Christmas gifts!

Do you know what ignition system it has now? Is it the original points? How good is your understanding of how the ignition system works?

I am happy for you! I got my first car, a 1973 Mustang when I was 16. Of course the car was only 7 or so years old at the time. LOL. Still have my second Mustang. I learned A LOT about working on cars with my Mustang. And that was before the 'internet'. We will be glad to help
 
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73 Grande will undergo three phase build process. Phase 1 is to make roadworthy. Phase 2 is interior/exterior restoration. Phase 3 is ++ performance.
Welcome to 71-73 Mustangs. I think you will find great advice here. Many of us are members of both VMF and this forum. I prefer this for my 73. One thing most of us remember when we were 16 with our first car. It was that we spent money on parts before we fully engaged our brains. You cite both electrical and tranny issues. So, let’s discuss each in detail before you buy fix it parts. There are folks here who can likely narrow the problem down to one or two parts. So, when you get the time, outline each problem in as much detail as you can. What do you do and how does the car respond. Is the car hot or first thing cold? If your car is stock, the parts are simple and it might be a very simple problem to solve.

Also, you should get a set of Ford service manuals; the books the dealers used to fix the cars. They are available in both paper form and as a PDF.

Again, welcome to the group.
 

MMoyer

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73 351c
Welcome to 71-73 Mustangs. I think you will find great advice here. Many of us are members of both VMF and this forum. I prefer this for my 73. One thing most of us remember when we were 16 with our first car. It was that we spent money on parts before we fully engaged our brains. You cite both electrical and tranny issues. So, let’s discuss each in detail before you buy fix it parts. There are folks here who can likely narrow the problem down to one or two parts. So, when you get the time, outline each problem in as much detail as you can. What do you do and how does the car respond. Is the car hot or first thing cold? If your car is stock, the parts are simple and it might be a very simple problem to solve.

Also, you should get a set of Ford service manuals; the books the dealers used to fix the cars. They are available in both paper form and as a PDF.

Again, welcome to the group.
I wish you were in Texas, I would be more than willing to help you here. What is the weird tranny issue? 350-400 HP out of a 351 C is very doable, but you will need a complete combination to make it work right, the correct converter for the cam you choose, some rear end gears, and a good trac loc differential with at least 3.25 gears, but preferably 3.55's. If the tranny needs a full rebuild, and you are doing a resto mod, you may just look into swapping an AOD or AODE in it...
when i was getting my car home for the first time the transmission would have trouble grabbing reverse and drive and would sometimes not shift at semi high rpm (around 3500) i got home filled transmission fluid next day drove it a bit and that seemed to fix the issue then last sunday i refilled all the fluids and went for a little drive around my area and it grabbed fine but it wound NOT shift into second when i would give it a little bit of gas it would make a sound that I can only describe as whirring like something just spinning freely not grabbing so i babied it home sorry for the lack of intelligent descriptions
 

MMoyer

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Welcome from Phoenix. Small upgrades like the ignition are good but before you start buying parts put together a plan for the drive train and then start collecting parts! Don't forget that car parts make great birthday and Christmas gifts!

Do you know what ignition system it has now? Is it the original points? How good is your understanding of how the ignition system works?

I am happy for you! I got my first car, a 1973 Mustang when I was 16. Of course the car was only 7 or so years old at the time. LOL. Still have my second Mustang. I learned A LOT about working on cars with my Mustang. And that was before the 'internet'. We will be glad to help
it still has the stock distributor and spark plug wires the spark plugs and starter i think were changed sometime before I got it. My understanding is alright not from a 'science' point but i have a general understanding of the chain of parts
 
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First thing is to invest in some good jack stands and floor jack. Mustangs are heavy, and gravity likes 'em. A floor jack (or scissor jack) alone is not safe when you are crawling around under a car. Stamped steel really isn't the best option for jack stands - I've seen the holes for the pins deform due to weight. Remember that you typically put one end of the car on two stands before you can put it up on the other two, so it's the total weight of the car that matters for the rating. Go for the 6 ton with the cast toothed posts. Mustangs are a lot less fun when you are squished beneath one.

Next is tools - a good set of ratchets (1/4, 3/8 and 1/2) with extensions and standard sockets. Spend a little here. There is nothing more frustrating than spreading the only 9/16's socket you have when you are in the middle of something. You can get these used if you look around - Facebook Marketplace, eBay, garage sales, flea markets are reasonable sources. Craftsman and Snap-on are brands to look for.

Drip pans and trays are handy and your folks will appreciate at least an attempt to be tidy. Bigger is good, deep is good too. Transmission fluid will splash everywhere if you have to remove the pan on your transmission, oil gets everywhere when you change it, and don't get me started on coolant. Recycle the fluids too - any place that does oil changes should take your used motor oil and transmission fluid. Most communities have recycling centers for antifreeze.

For the transmission - Could you shift it manually from first to second to drive?
 
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73 Grande will undergo three phase build process. Phase 1 is to make roadworthy. Phase 2 is interior/exterior restoration. Phase 3 is ++ performance.
Great info for the transmission. One thing to check, and I don’t think it will resolve the trans issue, is the Vacuum Modulator. There is a vacuum line from the intake to the transmission. If it’s missing or worse, disconnected, it could create a vacuum leak which would result in a poor running engine.

If you find it, start the engine and see if it is pulling vacuum by using your finger on the end of the hose. You should also check the vacuum modulator on the transmission by manually applying vacuum to it to see if it holds it.

For the transmission, it doesn’t sound good. If you’re sure the fluid is at the correct level and everything else is connected to it correctly, that whirling sound is likely the front pump not pumping up enough pressure for the transmission to engage the clutch pack. You might get lucky and it’s simply an incredibly clogged and plugged up filter in the transmission. The only way to check that is to remove the pan and replace to filter. Then you can see if that replacement solve your problem. If not, it’s likely time for a rebuild or a new transmission. But don’t go there yet until you’ve done those other steps because that’s an expensive proposition.
 

MMoyer

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73 351c
First thing is to invest in some good jack stands and floor jack. Mustangs are heavy, and gravity likes 'em. A floor jack (or scissor jack) alone is not safe when you are crawling around under a car. Stamped steel really isn't the best option for jack stands - I've seen the holes for the pins deform due to weight. Remember that you typically put one end of the car on two stands before you can put it up on the other two, so it's the total weight of the car that matters for the rating. Go for the 6 ton with the cast toothed posts. Mustangs are a lot less fun when you are squished beneath one.

Next is tools - a good set of ratchets (1/4, 3/8 and 1/2) with extensions and standard sockets. Spend a little here. There is nothing more frustrating than spreading the only 9/16's socket you have when you are in the middle of something. You can get these used if you look around - Facebook Marketplace, eBay, garage sales, flea markets are reasonable sources. Craftsman and Snap-on are brands to look for.

Drip pans and trays are handy and your folks will appreciate at least an attempt to be tidy. Bigger is good, deep is good too. Transmission fluid will splash everywhere if you have to remove the pan on your transmission, oil gets everywhere when you change it, and don't get me started on coolant. Recycle the fluids too - any place that does oil changes should take your used motor oil and transmission fluid. Most communities have recycling centers for antifreeze.

For the transmission - Could you shift it manually from first to second to drive?
i didnt think about that! i will try going from 1-2-drive.
 

MMoyer

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Great info for the transmission. One thing to check, and I don’t think it will resolve the trans issue, is the Vacuum Modulator. There is a vacuum line from the intake to the transmission. If it’s missing or worse, disconnected, it could create a vacuum leak which would result in a poor running engine.

If you find it, start the engine and see if it is pulling vacuum by using your finger on the end of the hose. You should also check the vacuum modulator on the transmission by manually applying vacuum to it to see if it holds it.

For the transmission, it doesn’t sound good. If you’re sure the fluid is at the correct level and everything else is connected to it correctly, that whirling sound is likely the front pump not pumping up enough pressure for the transmission to engage the clutch pack. You might get lucky and it’s simply an incredibly clogged and plugged up filter in the transmission. The only way to check that is to remove the pan and replace to filter. Then you can see if that replacement solve your problem. If not, it’s likely time for a rebuild or a new transmission. But don’t go there yet until you’ve done those other steps because that’s an expensive proposition.
I will look for that line today after school thank you, will the location of the filter be obvious if i remove the pan?
 

MMoyer

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As an OLD guy, my best albeit boring advice is to concentrate on stopping and steering before you even think about performance. We would hate to see you get hurt!! Make sure the car is safe... THEN go have FUN!!
speaking of safety i went our for a short test drive earlier and forgot to pull the parking break out, i realized this about halfway through and i had no trouble moving so that is another thing on my list!
 

giantpune

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As an OLD guy, my best albeit boring advice is to concentrate on stopping and steering before you even think about performance. We would hate to see you get hurt!! Make sure the car is safe... THEN go have FUN!!
This 100%. There's a recent video of a guy with 20yr worth of time and 6 figures worth of money fixing up a car but he was riding around on sub-par brakes and crashed the thing and got hurt pretty bad.
 

MMoyer

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Im 16 bought a 73 mustang with the 351c and auto transmission it is now occupying space in my yard. It runs and drives fine except for some electrical and weird tranny issue. my end goal is restomod with 350-400 hp/tq I want to do a lot of the work myself. I dont know any one that i could sit down and talk with about it so i came here. motor is in pretty good shape probably need new tranny and some body work including new floor pan. The first thing I plan on doing is getting a new ignition system (i think its easy enough to do myself) I dont have a whole lot of experience with mechanics so any advice would be greatly appreciated. also I would like to be able to daily drive it after the transmission and wiring are fixed
as a side note i would like to remove my ac unit and my smog pump neither of them function and my ac doesnt even have a belt wheel on it
 
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Welcome from NE, PA Great to see you digging in. For myself even though PDF manuals are convenient a hard copy is nice to have while near the car. I find a laptop sometimes not bright enough and sometimes you need to have multiple pages at your finger tips. Especially true while reading the electrical schematics connections from sheet to sheet.
 

Ron Tanzi

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Welcome from RI. Do you know what transmission you have? If the information was in this thread I did not see it.

Ron
 

Paul M

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73 loaded Q code car w/a 351 4v C6 it came with 2 cars in parts.
Im 16 bought a 73 mustang with the 351c and auto transmission it is now occupying space in my yard. It runs and drives fine except for some electrical and weird tranny issue. my end goal is restomod with 350-400 hp/tq I want to do a lot of the work myself. I dont know any one that i could sit down and talk with about it so i came here. motor is in pretty good shape probably need new tranny and some body work including new floor pan. The first thing I plan on doing is getting a new ignition system (i think its easy enough to do myself) I dont have a whole lot of experience with mechanics so any advice would be greatly appreciated. also I would like to be able to daily drive it after the transmission and wiring are fixed
If your existing transmission is a C6 have someone rebuild it. Use the stall converter necessary for your cam. If you want to be cost effective, build what you have as much as possible, instead of grabbing that "Resto-Mod" title and running with it. If you don't have a deep bank account, there's no need to replace parts that aren't even needed.
 
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Regarding the ignition upgrade. What I would do first is replace the points and condenser and toss a new rotor and cap on along with some new spark plugs. The points/cap/condenser and rotor are pretty cheap and they are adequate to the task of getting it running good. Once you have it running good then look at doing upgrades. This will provide you a baseline and is better than swapping parts on an unfamiliar car. If you can't get it to run 'decent' then you may have bigger issues that need to be tended to.
 
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My all time favorite vehicle is our 1969 Shelby GT500
In looking at the many posts from my fellow enthusiasts in this forum i can tell you they have offered some great advice already. Not to beat a dead horse, but the suggestions by "[B]MikeGriese[/B]" are dead on - especially about needing to purchase and USE a pair of jack stands. Years ago, while in the Army, I knew a soldier who changed his own oil. He neglected to use a jack stand and ended up with his chest being crushed. He survived, somehow, but he had a long, painful recovery. Please, don't you end up like him - or worse.

Another member advised you to check the vacuum line leading from the intake manifold to your transmission vacuum modulator. You can get a vacuum tester (good to have one) and make sure the modulator valve diaphragm is not leaking. If it is leaking or disconnected from the vacuum line your 1-2 upshift will be late, very late, and when it does slam into 2nd gear it will be at a fairly high road speed (40 - 50), and it will either go into 3rd gear very late, at a very high speed (70 or more), or it may not shift into 3rd gear at all. Those auto transmissions are very durable, please do not be in a hurry to replace it with a manual transmission., If you simply MUST replace it, consider getting a later model Automatic Overdrive (AOD). But, unless you have a really good reason to do so I would stick with what you have.

The ignition systems on those 73Mustangs is quite simple. Unless you plan to do some serious track racing I would not bother "upgrading" it to an electronic system. Despite claims made by those who sell electronic conversion kits, the stock system is fie unless it has a worn distributor shaft/bushing, worn breaker plate, the vacuum advance diaphragm vacuum line is disconnected or connected incorrectly, or the vacuum advance diaphragm is ruptured. I have a few YouTube videos re: the distributor, vacuum advance diaphragm, vacuum hose routing, that I think would be well worth your watching. Over time I will be doing ever more videos with Lynda (wife), and I encourage you to watch those videos, and videos done by others, to learn ever more about your car.

I have a nice little library of electrical schematics that I have annotated, show corrections to a few publisher errors, and am willing to share with you. The file is too large to attach to this posting. But, you can get the same schematics, and other manuals (shop) that will be invaluable to you from Forel Publications at:


The various manuals are in PDF file format, and are very reasonably priced.

Malachi, I sincerely suggest you feel free to reach out at ANY time with ANY questions you have about your Mustang. Between myself and our other enthusiasts you are going to find you have tapped into a huge resource of very experienced folks. You are also welcome to email me at [email protected]. I look forward to seeing photos of your Mustang, and hearing from you either through this forum, via my email, or both.

Here are some of the more relevant YouTube videos I put together re: the ignition system on our 73 Mustang Convertible's 302, which is very similar to your 351. I also attached an engine emission systems and vacuum schematic snippet from the 73 Shop Manual Volume 6.










I have a lot more videos on our YouTube channel (Gilbert Hale). Please feel free to peruse them to see what else I have that may be of use to you. And, if you have a question about something not covered in our videos yet,, let me know as often we choose to cover a video subject based on questions from other folks.
 

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