Why Did Everyone Forget About This Rare Mustang? - 1971 Ford Mustang BOSS 351

In this Rare Cars documentary, we are going over the history of one of the coolest yet most often overlooked Mustangs that Ford has ever built, the 1971 Boss 351
This r-code 351 Cleveland powered Mustang was a truly special car when it came out in 1971, yet it is hardly remembered amongst its BOSS 302 and BOSS 429 brothers. Why is that?
Today you are going to learn all there is to know about the 1971 Mustang BOSS 351 in episode 34 of our documentary series on the world's most fascinating cars.
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*Note, we are not historians. If you see an error in our research then please mention it in the comments!
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[@rarecars3336]

Which boss would you take if you could only have one? 🤔 BOSS 302 BOSS 351 BOSS 429

[@ralphthomas7868]

429

[@robertstone9988]

All 3.

[@skaldlouiscyphre2453]

Deuce

[@gray_space_alien]

I'm a 302 fan.

[@justme307]

Boss 429. But at original MSRP.

[@johnsmith-js9nv]

Cleveland. One of the best Ford engines ever made.

[@mikewasfaret9563]

They did not have 4 valve heads. The 4V stood four 4 barrel carburetor. Although the four barrel heads were huge!

[@jasmith1867]

The narrators expert credentials got busted on that blooper.

[@badass6.0powerstroke10]

It actually meant 4 Venturis in the Carburetor, hence the "V"

[@daveridgeway2639]

@@badass6.0powerstroke10 Correct!

[@matrox]

Yeh...I said to myself WTF? Was I missing something all these years?

[@mid-westbigfootresearchers8665]

exactly~

[@chuckselvage3157]

The 351 Clevo is a legend.

[@thomasbaker1961]

Graduated high school in’69 and my first job was a food market delivery boy. The other delivery boy got a Boss 302 for a graduation present, it was super sweet!

[@troyday5887]

In Australia we got the R code 351 in our 1971 falcon GTHO phase 3.which made it the fastest 4 door production car in the world at the time.

[@m42037]

Naturally aspirated unlike most supercars today that are supercharged, not a fair comparison

[@edwinyoung2719]

The gtho falcon was no joke … i like those cars and im not from aus

[@ytpaletot1]

I had a classmate, in France, in 1971, and her father sometimes came to pick her up with this car; we were stunned, with our friends!!! It was a very rare car at the time!!!

[@derektrieglaff9103]

I had a buddy in the mid 90's who had a neighbor, that had a chartreuse Boss 351 with silver hood and side stripes... ROTTING into the ground. Covered with about 200 lbs of pine needles and bird crap. I'm not a ford or mustang guy... but, that was a sad sight.

[@georgehuerta1990]

Yeah that would be a sad side I don’t really care for that mustang myself but man that car doesn’t deserve that put it in the paper and give it away to a father and son and make that a project car for the son. And to keep that car alive and not just let it rot away

[@mylanmiller9656]

there are a lot of guys around that are doing that, I know of a 1970 Cuda 340 6 pack that was scraped after years of buyers wanting to buy it. The owner just refused to sell.

[@georgehuerta1990]

@@mylanmiller9656 that sucks I hate owners like that me personally if I’m not gonna do anything with it I just can’t afford to do anything with it I’d rather pass it on to somebody else that’s going to keep the car alive. There was a 1995 Ford F150 that I have seen at this one house for years just sitting there on flats really nice body and everything went and asked the owner if he wanted to sell it and he told me know that the truck is just gonna sit there that was his first truck and that he just rather have it rot out and all I could do was just shake my head and walk away.

[@dukecraig2402]

​@@georgehuerta1990 I've seen so many cars like that go to waste sitting around behind barns and garages usually under tarps which is bad for them in their own way if you don't uncover them regularly and let them air out, cars I've watched sit since I was a little kid in the 70's that nothing gets done with them until the owner dies and his family sells it and by then they're reduced to just being worth parts because the frames and floor pans and just about every panel and door are rotted through. And it was the same thing with every one of those guy's for the decades they had them parked rotting away, "One day I'm gonna do something with it", after the first decade they should come to terms with the fact that they're not going to and get it to a good home before it's too late.

[@georgehuerta1990]

@@dukecraig2402 you’re absolutely correct it’s sad to see such iconic cars from every brand just sit in a field or in a garage rotting away. Let them go let someone else that wants to put the love into them and bring them back to life.

[@tonywestvirginia]

I just love the 71-73 Mustangs! (71 most) I'll take a "Flat backer" any day!

[@ralphthomas7868]

A ball buster that punched well above its weight

[@user-nn6qc2tc1v]

The 1974 AMC Javelin with the Typhoon 401 had 5 hp less than the legendary Firebird SD455. Also the Javelin could be had with a 3:91 rear end all the way to a 5:1

[@frogdude21XXX]

The term 351 4V means 4 Venturi (4 barrel carb), not 4 valve as you stated. ✌️🐸💨

[@awilson2385]

Figured I'd find someone in the comments that corrected the mistake. Yours is the first one I found that correctly identified what the "V" was for. Nice.

[@williamfoster9039]

I didn't forget this Mustang! Not now, not 20-30 years ago!!😁👍🛠️⚒️🔧

[@-POISON-]

Always loved this body style. Boss 351 or Mach 1 are the ones to have.

[@scottslater-nb5ch]

4v means 4 Venturi the amount of carby throats Ford Australia's version the HO engine produced 385 HP with 780 Holley.

[@financialconnectioninc]

The 351 Cleveland did not have 4 valve per cylinder heads..

[@robertstone9988]

Common mistake with young guys they see 351 v4 and thank 4 valves lol they don't know shit about carbonation😂. For kids who don't know 4v stands for 4 venturi, or in English 4 barrel carb.

[@douglasmcdowall5006]

I came here to comment that aswell.. 4v.. 4 Venturi or 4 barrel carburetor. @@robertstone9988

[@rarecars3336]

You are indeed correct that is my mistake it is in fact NOT a 4 valve but for 4 barrel carb. I have a 2004 Mach 1 which is a 4.6L 4V which has 4 valve heads so I applied the same logic to this motor but I was in fact incorrect. Thank you for the clarification.

[@ralphthomas7868]

Big port, larger valve head stamped with a 4, sometimes stamped 4 with a dot

[@robertstone9988]

@@ralphthomas7868 I have a Cleveland Ranchero

[@rodmoore1577]

In 1972 a man would pass by our house everyday a little past 5 driving a red Boss 351 with the black accents. I made sure I was outside everyday to watch him drive by. To this day that is my dream car. I just want to say to him whoever he was or wherever he is thanks for the memories. This was in Texarkana Texas

[@Tshade67]

My uncle bought a '71 Boss 351 right after he returned from Vietnam where he served as a Marine. It was white with black stripes and black interior. Unfortunately it was an automatic but still would get up and go. I remember him talking about the aftermarket/day 2 performance parts it had but I was only 4 or 5 years old at the time and the only thing I remember for sure was headers and a larger Holley carburetor. It may have had an aftermarket intake manifold, not sure about that. I also remember going to the drag strip with him and him running it. If my memory serves me right it ran somewhere in the 11s with street tires and would levitate the left front tire a couple of inches in the air on launch. I do have a pic of that somewhere and you can clearly see daylight under it. We both wish it was still in the family. BTW it was a daily driver and was driven to and back home from the track. I do remember he had some sort of exhaust dump he uncapped at the track, but it was still loud with the full exhaust.

[@DonDrogowski]

No such thing as a Boss 351 with an automatic from the factory.

[@stacyhazelwood4033]

@@DonDrogowski I thought the same thing when I read the post. I could be wrong, but I thought ALL Boss 351 cars were 4 speeds.

[@DonDrogowski]

Boss 302 and Boss 429 were also only 4-spd from the factory.

[@Kgio-2112]

​@@DonDrogowskiyea, when I saw automatic I was like. Ok. Yea. Sure it was

[@stevefisette1709]

I ordered a Grabber Blue 1971 Boss when I was in Viet-Nam. It was in the dealer's lot when I got home. Beautiful and fast.

[@terrywalchuk4793]

The Boss 351 engine one of ford better ideas truly a remarkable engine the baddest of the small blocks of the 70’s

[@mcm95403]

In 1971 a neighbor down the street bought a bright red BOSS 351. We used to ride our bikes down the street and just stare at it. That was one of the most beautiful cars I've ever seen in my 60 years.

[@hailstorm1986]

It's crazy to believe that there was actually a '71 boss 302 made as a prototype and someone actually found it and is trying to restore it and they've actually been tracking their progress here on KZbin.

[@DemnRaig80]

Why?

[@jwrockets]

Yeah, I've seen him. He comes off a bit of prick to me. Your milage may vary.

[@stevejarred6484]

Even though I grew up more of a GM & Chrysler guy, I do have a soft spot for this era of Mach I and Boss Mustang. Growing up in suburban Detroit, seeing one of these cars in silver over Ford blue always gave me a good feeling like I was cheering for the Detroit Lions!

[@ricktaylor3748]

Ford actually built a scant handful of 1971 Boss 429 ci Mustangs. I have a friend who owns one. It handles like a stagecoach.

[@carolnelson9269]

Pictures posted would be neat. Understand the rarity. Nothing but the car would be great. Car, engine bay, interior shot.

[@godsowndrunk1118]

Like the stagecoach analogy....I used to say my big block 67 Mustang handled like a chariot.

[@ricktaylor3748]

@@godsowndrunk1118 👍

[@DonDrogowski]

They were not Boss 429's in 1971. They were standard 429's and not the semi-Hemi heads of a Boss 429.

[@ricktaylor3748]

@@DonDrogowski I saw it several weeks ago. The valve covers say "Boss 429" It's probably an old 10:1 compression 375 horse slug.

[@Barbutt]

I actually saw this car at my local market within last 2 weeks and was astonishing at the size. I had guessed 73… but was corrected when I asked the driver. Not a BOSS… just surprisingly hUgE!

[@blackgenesis7472]

only 2 inch longet and wider then 69/70

[@PhilBesch]

I hated my 71 Mach 1. One day, when it broke down, again, it was near a 79 black on black Trans Am. So I sold my Mach to my friend so I could buy the TA and never looked back. Because I was used to not being able to actually look backwards through that stupid rear window. Also, my friend was happy to get my Mach 1 because he now has it with his 71 Boss. We did a drag race once. He was surprised that the 6.6 got the win. I kept telling him that those cars were land yachts. But it was still fun.

[@terrywalchuk4793]

Ok what ever you say he must have been a bad driver a 351 C 4V would smoke a smogged out 400 any day maybe the screaming chicken decal on the trans am hood made it faster Lol cars of that mid 70’s and late 70’s period were slow they replaced the performance with decals that the way it was after 1972 GM guy those cylinder heads of 351 C 4V had valve sizes of 2.19 intake valves and 1.71 exhaust valves canted-valves or semi hemi cylinder heads the same size valves as 454 Chevrolet engine deep breathing cylinder heads means more power think about it

[@PhilBesch]

@terrywalchuk4793 Both are 6 sec cars. Factory the quadrajet was set to open later, which made it slower. First thing I adjusted. Next is the big difference with their ignition systems. I can tell you from first-hand experience, the Mach was a real pain! The Pontiac, only thing that I did to it was changed wires and cap. The Pontiac also wasn't really smoged out then. The latter years like 81, it definitely was. Mine only has a cat and evap canister. And finally, the Boss and Mach were auto's. I can go through all the details about the 3 cars. I don't have the nostalgia glasses on as I can literally park all 3 next to each other and highlight the pros and cons. Like the Bandit will be pulled over more by cops. The red Mach got pulled over once because the cop couldn't see me from the rear. Then he tried to explain how that could be dangerous to drive. I thanked him for pointing that out rather than asking him how would I fix it. Like, bro, it's built this way. Hope this helps.

[@philsocks3386]

I used to wipe the streets with trans am with 70 mach 1 351 Cleveland 4 speed.

[@PhilBesch]

@philsocks3386 A 1970 was a different car all together. I wanted one of those real bad, but I missed a chance getting 1 when I was also after a 69 Dodge Charger. I'm sure you gave some firebirds a run for their money.

[@gordocarbo]

@@PhilBesch Hated the Duraspark boxes from Ford .Always left me stranded .

[@mry82]

Sweet, a new one! Today, I have been binge watching the videos that were released before I subscribed, lol. Cheers!

[@louiswoodbeck249]

Great videos, awesome summaries. Look forward to each new video you publish

[@jasmith1867]

I give this video a 4 Vs up. For blooper value.

[@richardobryan8041]

Drove a 4 speed 351 (A little juiced) 71 that was for sale years ago and gotta say, it was one fast/fun drive. always loved the bigger body change. love the fastback cars of every manufacturer from the era. Wonder what a fastback couger woulda looked like....

[@chawenhalo0089]

Always like the mach1 shape. Would love to see what could be done as a restomod. That 351 seems like an American Aston, love it.

[@myleslong5584]

Love the W-30 tag on front of the Mustang at 1:10!

[@racer6583]

There is one mistake you made you said four valve,a Cleveland had eight canted valves per head, the 4V on a ford stood for the venturis , i.e. the carburetor a 4 barrel. Other than that you are dead on the mark. Good job on shinning a light on the only race car that never raced for ford.

[@ox-cetane4887]

Boss 351 engines also had an oiling problem. they oil the cam before the crankshaft. Smart Ford guys corrected the problem

[@cjespers]

The rarest boss. Thanks for the video.

[@BigBoss1292]

The 71-73 fastbacks are hands down my favorite Mustangs…I adore all the ones that preceded it, but something about these cars just look better in my opinion and the Boss 351 is one of the coolest muscles cars ever made

[@henryjohnson4061]

LOVE LOVE LOVE these cars!!!

[@jameshaynes8489]

great info. thanks

[@tj-597]

Had a. “72” Grande with a 351 Cleveland (didn’t appreciate what I had) the rear window was pushed in so visibility was ok.The only thing I didn’t like about it was the rear-end was a little squirrelly.The interior wasn’t great but functional

[@hkguitar1984]

I love the BOSS 351, great video. Back in 1982 my older Cousin had a Grabber Blue BOSS 351, the only modification was a timing gear set that replaced the chain. That engine with the timing gear set had a totally unique sound all its own.

[@clevlandblock]

I owned a Boss 351 back in the early 1990s. I first fell in love with one sitting in a Ford showroom back in the autumn of 70. Main complaint - Ford forgot to equip the car with TORQUE. It was geared and cammed for stoplight racing, period. As far as the body style goes, that's an acquired taste. Is it/was it a forgotten car? I think not, especially if you are a Ford guy. For a one year only model, it got a pretty fair amount of attention in the car magazines of the day. They just lagged in collector status for a few decades relative to the too cute and cuddly 69-70 Mustangs.

[@rarecars3336]

I agree on the body I used to dislike out now i like it. I think changing the tail lights could make a huge difference. I think these were under appreciated by non ford people, most hardcore ford guys know about them but I feel like most other people unless they walked right up to it couldn’t tell it apart from a Mach

[@theone861]

The 71-73 Mustang is smaller than 2005 - current models.

[@tomstamatakos8027]

Thabks for a great video on these cars! Always liked this generations Mach1 the best, was cool to learm of the Boss 351 variant 👌

[@ZacLowing]

LOL, 4v heads means 4 barrel carb heads. The 4 valve heads didn't come for a couple of decades. 4:40

[@ralphthomas7868]

Big port, big valves heads stamped with a 4, sometimes a 4with a dot.

[@jameshaynes8489]

I was always a boss 351 guy. a big block chev guy designing a ford small block 351C, they really come to life with boost, ports and valves were large

[@txboss2318]

All time 2nd favorite Mustang. I've never owned one, but I did own a 71 429 SCJ 4 speed and a 71 351 4V 4 speed convertible and loved them both. My all time favorite is the 2013 Boss 302. A street beast!

[@rono3045]

The boss 351 is an all-out race motor solid lifters ,780 double pumper 11 to 1 compression the only problem was bad block design too thin and pour oil distribution..otherwise that motor would dominate NASCAR circuit back then

[@olikat8]

1971 Ford "Banana Boat" Boss...not forgotten, just not as desirable because it's almost a Torino

[@rarecars3336]

Lol I never heard the banana boat name thats funny

[@torque3022]

certain years of cadillac escalades have banana tail lights

[@philsocks3386]

I've seen these cars run 10 seconds in the quarter mile with mild 460, street cars.with tags.

[@olikat8]

@philsocks3386 figures, not doubting that, but a Dart with a 440 can do it as well and not look so ponderous. In the right colors & options, this era is not bad. But they are big, with ponderous proportions. That's all I was saying

[@Zekais]

@@olikat8 I admit that after I first saw a sinister '71 Mach One 429SCJ in black with the argent stripes, I never thought of that Mustang SportsRoof generation as looking ponderous. Dangerously badass, but not fat. The paint details/stripes could make it look more or less ponderous, I'm sure. I'm not sure about the Mustang, but I read at the time that the '71 Cougar was actually lighter than the '70, although it looked somewhat bulkier. When I first drove my 1st wife's '71 Mach One, I was prepared to be disappointed, but I was pleasantly surprised to find how responsive, flat-cornering and light it felt to me. It wasn't quite up to my '70 Cougar Eliminator, but it didn't have the Trans Am oriented suspension of that Boss 302 powered Mercury, either. A really nice, confidence inspiring car to drive, IMO. It was kind of a stripper for a Mach One, aside from an automatic (yuck) trans, so maybe a hugely optioned one with smaller tires than the Mach One/other performance variants had would have been more of a pig, but her's was a joy to drive.

[@kingdomculture5743]

Awesome vid! I sure would like to own one!

[@rnt45t1]

I still like it!

[@tomstrains4129]

My dad bought a 71 convertible when we were kids (early 2000s). Bought it for 1,000 bucks off a guy who was bracket racing with it. The PO took out the inline 6, painted it black, threw in a 70s Lincoln 460 with cherry bombs, a C6 transmission with a 9 inch rear. It’s what started my love of cars although it was Frankenstein’d. Dad sold it right as I turned 16, but the car rides always made us laugh and we’d always wait outside to watch and see it try to start and wake up the neighborhood. The sound alone can make any non-car lover grin. On the search for a 71-72 now, fastback or convertible is fine with me! Not as pretty as the other first gens, but definitely sentimental.

[@321-Gone]

4::37 - They're not 4 valve heads. The 4V means four venturis. 4 Barrel carburetor

[@mpetersen6]

4 valve heads on an OHV V-8 may be trick but for the mass you lose on the valve weight you gain it back on the extra mass in the valve train. Ford actually built some prototype/engineering 4valve heads for small blocks on the late 60s. Various GM division messed around with them too.

[@dieholdendie]

Had a 73 Mach1 fastback 351 4v , 4 speed with Hurst shifter and 3.5''s in the late 80's. Went really well, drove it hard Don't remember ever being worried about visibility out the rear window, would have been the last thing on my mind

[@mpetersen6]

Not a fastback. More of a flatback.

[@Kgio-2112]

My brother had a 73 mach one q code , 4 spd back around 1986-87. He didn't lose many races.

[@steverifenberg8859]

Had a 73 fastback, couldn't see crap out the back window 😅 wish I still had it

[@rarecars3336]

Lol it’s so funny how they definitely didn’t realize that till they already made the first prototype and were like “eh it’s fine”

[@psa10hunter94]

I’ve been a Mopar guy from day one, but the 71 mustang Mach 1 is my favorite mustang.

[@shanechostetler9997]

I actually love that body style. Wish I still had my 351 CJ ‘73 Mach 1.

[@Joshua-uw7wm]

I love this style mustang it's second to me behind the Fox body

[@LR-my2di]

I bought one of these in 1980 from an airman in Valdosta, GA just to resell. I was in grad school and had no place to keep it. It had been very well maintained and was silver with the factory 15" X 7" chrome plated Magnum 500 wheels. It was said to have been "dyno tuned" by a For "expert" and the only mod was a 800 cfm Holley. It was a close runner to my stock 1970 GS Stage 1 that I'd bought new, and that car had never lost a race to any other stock muscle car. The Boss 351 would beat my Chevy buddy's 1970 Z/28 by 2 lengths every time we raced. I ended up selling it for $3800 (1981) through the old $25 Hot Rod magazine ads of the day, but I was left with some very good memories. Good ol' days for sure.

[@gardenave2531]

Mopar guy here. Why are the Mach One’s so cool? Generally don’t like Ford lines, but the these.. that’s a damn fine automobile.

[@rarecars3336]

I like the body style! I think if they switched these twilights it would truly make most people rethink their opinion!

[@josephg41]

I knew about this one but it was the last Boss I heard about. It really wasn't one to forget about but I think it's because it's the less desirable '71-73 body style and the middle child between the Boss 302 and Boss 429. But I'd love to have one, almost more than a boss 429 actually, it's more of a daily drivable car, and one that corners better and is a little bit easier to work on due to the extra room compared to the big block cars. It's a shame they're so rare. The Boss 351 and '71 Mach One were the last hurrah for truly fast Mustangs for a long time.

[@gordocarbo]

True...mid 70s were horrid for all Charlie Angels stangs, Monzas etc bad time for the big 3 Toyota was getting real popular back then.

[@dukecraig2402]

It was a Mach 1 instead of a Boss but still it was a 71 that James Bond was tearing around Las Vegas in with Tiffany Case next to him in Diamonds Are Forever, that makes the 71 Mustang officially a Bond car and it don't come any cooler than that.

[@rarecars3336]

YES, I am a huge bond fan and when I saw him finally driving a Mach I was so excited. The Aston from the living daylights is still my favorite though

[@brycemorrill8764]

Lovely car

[@GrandPitoVic]

This was my favorite body style Mustangs.

[@danbaumann8273]

I think they're freekin' gorgeous. Can't remember the first time I saw one I think a car show, but it was a looong time ago. Was like 😮😘😍

[@billypater5287]

WITHOUT A DOUBT THE MUSTANG 🐎 MADE HISTORY,FOX BODY,i owned at least four 69 Fastback,67 Notch back 70 Fastback 3 Speed on the Floor loved 😍 THOSE Stangs

[@dalebecker6583]

Yes, it’s bigger than a 65 by a lot, but if you compare it to 69-70, change was not so much(size)! And, yes, factory rating was 330hp, but if you look at later Dyno tests of stock BOSS351, it made 400 hp! Even the M code 351 4V that came in Mach1, made 375hp, not 300 as factory said!

[@tomstamatakos8027]

Yeah I was thinking something was off with 11.7:1 compression and big valved heads something wasn't adding up. Expected more like 400hp💪🙂

[@edcain9492]

Exactly,the Quarter Mile Times weren't too far Behind 427SCJ❤.

[@justme307]

Who forgot it? I didn't.

[@stevejohnson6858]

I felt the same way about the body changes in the 71 Mustang as I did the changes to Mopar B-bodies in the same year. For me, both became land yachts. Great motor, ugly Mustang.

[@GroovyBabyYeah]

It grew on me, unique but not ugly unique

[@terrywalchuk4793]

Sleek

[@RobertSmith-le8wp]

My Dad used to have a 1973 Charger w/ a 400. While not necessarily ugly it wasn’t nearly as good looking as the ‘68-‘70 ones. Unfortunately 1973 was close to the end of the line for the Charger. They became a personal luxury car and then went away

[@ShaunHensley]

That is the common opinion of most post-70 American cars. Complete smog dogs

[@blackgenesis7472]

71 is ultimately muscular car design comared to prior years. very similar to 69 GT 500 - designed after that.

[@jokerzwild00]

Im weird i guess, I always loved the chunky boi Mustangs of the 70s. I grew up in the 80s and 90s, and they were more classical Mustang than the Fox bodies driving around at the time, to me. One of our neighbors had an olive green completely ragged out Boss 302 up on blocks in his yard, i always dreamed of getting that car and fixing it up. The name alone made it cool.

[@mylanmiller9656]

As tested by the Hoit rod magazines of the day, the Boss 351 ran better quarter mile times than ether, the Boss 429 or the 429 super cobra jet. The 1971 Car was 300 pounds heavy than the 1970 car. i would have loved a 1970 Mustang with a 351-Boss engine.

[@JC-gw3yo]

The 351 Cleveland produced the most horsepower per cube of all small blocks, according to Richard Holdner. A fantastic engine even in this heavy car

[@fredclements6843]

I have one an I’ve loved it ever since I was kid best one it was the MUSHORSE! I looked for ever an finally got one!!!!

[@leonardhirtle3645]

The v in 4v stands for Venturi as in 4 barrel carburetor. The heads on the boss 351 did have huge valves.

[@WingWalker1]

I guess I'm not "Everyone" because myself and all of my friends haven't forgotten about this car.

[@SteveBueche1027]

My Aunt had one when I was young (10) but even then, I didn’t like it and thought the Stang was finished. When I got older I had a Gran Torino fast back 2 door, in gold with a 351M. I had major rust issues.

[@bricefleckenstein9666]

We didn't forget the 1971. It NEEDED that Boss 351 just to try to keep up with the 1969 Boss 302 due to it's BLOAT (though to be fair, the bloat was in part to be ABLE to fit the 429's extra width over the older FE-series 428 that had to be custom-installed in the older narrower engine compartment of the 1969 and before).

[@whytebearconcepts]

7:35 "The first rule of Italian driving, what behind me is not important" ~Franco, Gum Ball Rally

[@saleen367]

Four valve heads in 1971 would have put the rest of the auto industry on their heels. Sadly, not the case, but the heads were stellar none the less with 2 canted valves per cylinder. Also, while I personally love the Boss 351 because of its engine, the 69-70 Boss 302's would probably have an advantage on a road course due to their weight advantage. Don't forget to mention the one of one 1971 Boss 302.

[@AG-fs8yn]

In person, they look pretty cool. There’s one that goes to the same autocross events that I do, but it doesn’t race in CAM-T with my Bullitt

[@mrfairsthename7470]

Looks wise the Boss 429 hits my spot .

[@jamessharp9790]

The development was the earlier Boss 302 for Trans Am series. Needed x number of models for homologation. Boss 351 being a 351C 4v with solid cam was pretty stout.

[@mpetersen6]

From 1970 on the manufacturers no longer had to offer a 5 liter V-8 in a production model to meet SCCA A/Sedan rules. That's what the 5 liter TransAm cars were. This allowed Chrysler to enter using destroked 340s. And Pontiac to enter with destroked 400s. AMC took advantage to destroke Special Service Block 360s. These were 360 blocks with 390 webs and water passages. Sold over the parts counter unbored. The 1970 TransAm series in many ways was the high point of Road Racing in the US imo. Solid factory involvement. Competitive racing and great drivers. The 69 and 70 Boss 302 had great acceleration out of the corners. One reason was the cylinder heads (1). Another was the short deck height which allowed short pistons and short rods. Also a shortervalve train. A 3 inch stroke is about as big as you want to go in a Windsor short deck. To go to 351 they had to increase the deck height. A lot. 1) The Boss heads flows lot better than the Chevy heads. So do the 340 and AMC heads. But it's not just flow at maximum opening. The valves spend a lot of their time with a lot less lift. Ford also got creative with carburation. Building inline 4 barrel cards that were essentially 4 barrel Webers. The SCCA shot those down pretty quick.

[@jamessharp9790]

@@mpetersen6 I remember. Auto lite inline four barrel

[@patrickkelly9721]

I've always preferred the look of the 69-70 to the 71 & newer.

[@rarecars3336]

I do as well

[@Rick-last1]

I had a 1971 Mach 1 and it had an automatic trans and a 2 bbl carb. I still smoked Trans Ams any time I ran against them.

[@tomedwards7847]

I am pretty sure it put out more than the advertised 330HP. Probably closer to 400 (They underrated allot of engines back then for insurance purposes)

[@sombra6153]

The Boss 351 motor would have been more expensive to produce and harder to meet impending smog regulations over a hydraulic lifter 351 Cobra Jet. The last hurrah was the 1972 Mustang 351 HO which still had solid lifters but the compression ratio was cut and the cam likely changes - a detuned Boss 351. Sold about half the numbers. To date, I never drove a 71-73 sports roof, but would love to have one, especially a sports roof. The Boss 351, while rated at 330 horse power, was actually cranking out around 380 gross. I recall reading the road test where the 71 Boss was clocked at 13.80 in the quarter - that car reportedly had headers. Real world, if traction could be achieved was closer to low to mid 14s.

[@mcm95403]

Funny, my current V6 Challenger is quicker to 60 and almost as quick in the 1/4 mile, has the same top speed, but gets 37 mpg on the highway, stops better with the 4-piston Brembos and will pull 1.2+ g's. Amazing how technology has advanced things. I'm not building any more cars, but this body is one I really wished I had built one of.

[@Musclecar1972]

The funny part is the Boss 429 was only produced in 1969 and 70, in 1971 the 429 was a Super Cobra Jet motor, not the Boss. If you wanted a Boss in 1971 you got a 351 Boss.

[@angelo_giachetti]

1975 I was 19. I bought a 71 Mach1, 351C 4 brl. silver with red/black base interior but it had factory tach, 4speed, no posi, no ram air but did have AC, rear de icer. I raced a 1970 AMX, 390, 4 speed. I pulled ahead at the top of every gear but not by much. We did it several times. 11 months later I traded it for an F100. That was a mistake.

[@angelo_giachetti]

And my cousin bought a new 1972 Mach1 Grabber blue, 351C, 4brl with ram air, auto trans, no ac. His had premium black int. A neighbor, Sammy had a black on black 71 Mach1, 351C Ram air, 4 speed with posi. It was a low option Mach1. I lived a few miles from the Chicago Ford stamping plant. There were alot of Fords around here. One guy had a 70 Torino GT, dark green, 429, 4speed. Another local had a 71 Mach1, red, 429 ram air, 4 speed. I never seen a Boss Mustang back then in the mid 1970s.

[@terryharris2569]

Okay I've been waiting for someone to talk about the beast of 1971 Mustangs that I owned, yea the Boss 351 was hot, but not as hot as the Mach1 429 SCJ not to me mistaken for 429 CJ which pops up 99.9% of the time. The difference between the 429 SUPER COBRA JET W/ DRAG PAK and COBRA JET was the SCJ was a solid lifter cam like the Boss 351, The SCJ was rated at 375hp for insurance, it got air & gas from a Holley 780cfm double pumper carb, pumped out more like 450hp came with C6 auto 3:91 Posi traction 9inch, trans cooler, no air, staggered shocks, I hate that I sold mine after having it 12yrs, I was young, dumb didn't realize how special it was they made 500 SCJs to this day the place I've seen one like I had a real "SCJ" is rolling cross the block on Barrett Jackson sold for 176,000

[@johnlambert7056]

Once people realize the low numbers available , R code, 4spd, compression . Plus awesome looking . Prices will start going high north soon !

[@AA-ke5cu]

I had a 351 Windsor in a stock 1986 Ford f150 xlt supercab lariat package; took all the anti pollution devices off ;threw on a set of blackjack headers. Stock posi rear. Engine made in Canada. Dual gas tank switch; full 8 foot bed with cover ;and matching paint Lear top with screens and sliding windows dark navy blue and white. Heavy bitch but she moved when needed full or empty. Never had a problem with that engine.

[@jasonamerica7618]

4v does not mean four valve, it stands for four barrel (venturi)

[@pinocarrozza1645]

Guessing front end design of this got carried through into XB Falcon here in Oz? Def wouldn’t say no to one of these… unless I was being offered a ‘70 Boss at the same time 👌

[@karlmoltzan6196]

You have one big m7stake. The 4V heads do not mean it was 4 valves per cylinder. They were 2 vavles per cylinder. The 4v was used because it had a 4 venturi car berator. The 2V heads were for the 2 bbl or venturi carberator. It is not like the mod motors the came out in the 1990s into the 2000s.

[@daveridgeway2639]

The 1965-1970 Mustangs where based on the Ford Falcon. The 1971-1973 Mustangs where based on the Ford Torino. I you where to raise the cars up on a lift side by side you can see what I am talking about. Also take note of the engine compartment firewall on the 1971-1973 Mustang Vs. the Torino. You will also see the same with the 1967-1970 Vs. 1971-1973 Mercury Cougar. Please reply. Dave...

[@mcjams66]

They dyno'd @ 386hp and for those that say they lacked torque, the torque curve was just slightly better than the LT1 Chev and with 50 more hp.

[@ryanmuir6338]

I like the integral power steering and concealed wipers, but not the rear glass that is more like a sunroof than a windshield Good engine, but the crank should have been forged steel like the B302 and LT1 though

[@Zekais]

Glidden, Roush, Nicholson and so on ran the Clevelands with stock iron cranks to 9500+ RPM in Pro Stock with no failures. Yeah, steel cranks are better, but there was nothing wrong with the Cleveland crank. The NASCAR guys would pay huge money to have Hank the Crank or somebody like that make a steel crank for them. But running 7200-8600 RPM for 500 miles or so on a race track is a lot different than running high RPM for less than 8 seconds down a drag strip, too. Integral power steering? That's a new one on me. I've seen a number of 71-73 Mustangs without any power steering. Rare, but not unknown. My 1st wife's '71 Mach One had manual drum brakes, but I don't remember if it had power steering. It may have, but there's nothing "integral" about the power steering on those cars. The same general layout and design as the previous generations of Fords, with minor changes for the chassis differences.

[@ryanmuir6338]

@@Zekais I still have an old magazine featuring an in-depth 351C build for 650hp at 9500 rpm. The integral power steering I'm referring to is the design change eliminating the slave cylinder. You know, the bane of header installation because a drop bracket had to be used for clearance. With fatter, stickier rubber up front, over time the bolts tended to rip out of the frame rail internal nuts because of the increased leverage. Parallel parking went a long ways to causing trouble. My 65 Impala debuted with integral design power steering, so it's bizarre how long it took Ford to adopt it. Must have been "Bunkie" Knudsen that finally got it done.

[@Zekais]

@@ryanmuir6338 Ah, okay. Guess I just don't know that much about power steering. It was not unknown for me to remove the belt and sometimes the pump/hoses on cars I owned that had power steering, since it might have been "stealing" a horse or two. I do hate the slave cylinders of that era, so I can see how eliminating them would have been a boon. Thanks for 'splaining what you meant.

[@jimmymccormick142]

The baddest of the bad mustang Ford power forever baby keep on pulling the knot out of them boties and the horns off them mopars l love it

[@AG-fs8yn]

The boss 351 sounds a lot like the 2001 Bullitt, but with a ton more power

[@jimmyhamm6041]

At 4 minutes in I know where one sits as we speak . Not even 50 miles from me I would love to get $$ up to put up an offer . It is in good shape all there & sits outside .

[@johnvaluk1401]

Four valve heads? News to me. 351-4v means four barrel(Venturi) carb

[@mikev1759]

As I was about to comment, I saw another comment at the top referencing what concerned me. I'd guess that it's peppered throughout, so I'll only mention that you must have misspoke when claiming that it had 4 valve cylinder heads :)

[@jackylsmith8138]

Ford designed the 71-73 Mustang around the 429 engine. So they had to make things a little bigger. It is a pain to work on a 428 or even a Boss 429 in the 69-70 mustangs. The 429 in the 71 is easy peasy to work on.

[@vadenk4433]

It’s a crying shame that Ford didn’t drop the BOSS Cleveland into the 1969-70 mustang. Imagine the legend that would’ve become.