Question For Our Readers: 1973 Triumph Stag


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I knew this one had the typical Triumph Stag engine issues as soon as I saw the picture with the car’s nose in the air. At least this owner pulled the engine before calling it quits! The Stag is well-known for its engine woes, basically having two TR7 slant-four engines merged together to make a 3.0 liter V8. Casting issues, cooling issues and an unusual cylinder head stud arrangement have led to an estimated 25% of all Stags produced ending up with engine transplants. This one was sent in by reader Jim S., and is located in Trenton, New Jersey. It’s up for sale here on eBay, where bidding is below $1,000 but hasn’t met a reserve yet. Ultimately, though, I have a question for you Barn Finds readers to answer!

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This looks like a pretty solid Stag, with mostly original paint and what appears to be little to no rust. It’s been stored inside after the engine was blown up until last winter. Since then it’s been outside and the owner wants to pass it on (maybe they are making room for the Spitfire in the background).

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A Stag has a really nice interior, and apart from the damaged wood at the shifter (which you are probably going to have to replace anyway, keep reading please) this one looks pretty nice. The seller does say the original Triumph four speed is included.

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So here’s my question. What would you put under this hood? I’ll help you out by giving you the ten options that I have seen or heard of.

  1. Original Triumph Stag 3.0 liter OHC V8 (obviously, the easiest fit of all)
  2. Triumph TR6 2.5 liter I6 (bolts up to transmission, easily adapted as Stag descended from 2500 sedan)
  3. Buick 231 V6
  4. Buick/Olds/Pontiac/Rover 3.5 liter V8
  5. Ford small block V8
  6. Chevrolet small block V8
  7. BMW I6
  8. Nissan I6
  9. Ford 2.8 V6
  10. Ford 2.3 I4 turbo

So, I’m wondering–which one would you put in? Me, since I have three sitting there waiting to do something with them, I’d install a TR6 engine. However, I’ve driven a car with the Rover 3.5 liter and it makes one heck of a nice car! Tell us what you would install in the comments, and don’t forget to include the reason why!

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  1. Grr

    The original engine, rebuilt with all the fixes available these days. Maybe tuned to deliver a bit more power…

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  2. Bruce

    Buick/Olds/Rover 215 V8 because I have one sitting in the shop.


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    • Ross W. Lovell

      Greetings All,

      I’m with Bruce.

      “All the fixes” only gets you an adequately designed engine that is less trouble-free, not actually trouble-free as typical Brit maint schedules developed in the 50’s apply.

      Played with several of these, numerous issues, enough to make me avoid NOS parts, and not just the Lucas ones.

      The Buick V6 can be built the most potent and least expensively but I’d likely opt for the Olds 215, keeping with the V8 theme but mindful of the fact the car’s soul will enjoy one that runs regularly.

      Have to give credit to the owner, looks better than just about every example I’d ever seen over the years.

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  3. grenade

    Because it’s a direct swap, the one that fits the easiest. Get it to run and drive, then decide on the full restoration or sale. If you’re going full on “I don’t care what it takes, I want it to be fast and cool”, a BMW 8 cylinder, a Toyota 8 cylinder, modern engine & trans with EFI.

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  4. Healeydays

    Hellcat Hemi with nitrous of course.

    Seriously, if I had a 215 like Bruce has sitting in the garage, I would do that. If not, the web has many stags converted that you could learn what works and doesn’t. With a Stag, I wouldn’t mind if it’s not a purebred and it’s turned into a Tiger wantabe…

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  5. Kevin Harper

    Well to stay with something British and a V8 how about a Jag AJ8. I know the Jag motor had some issues originally, but they have been all solved and I am seeing a few of them with 200k on the clock. The motor is light and relatively small, and makes good horsepower and I like the sound.
    Since I wouldn’t have to meet emissions I would do a stand alone fuel injections and back it up with a tremec 5 speed. Yes this is mostly bench racing, but it is fun to contemplate

    Kevin Harper

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    • Joakim

      Hi Kevin,

      I think you’re on the right track with suggestion the AJ-V8 engine, which is also essentially the same as Ford’s Duratec engine. You’d probably easily find a suitable donor car in a Lincoln LS with the AJ30 or AJ35 engine…

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  6. skloon

    Go weird Volvo B5234t

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  7. Paul

    11. Restore the Spitfire in the background.

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  8. Bobsmyuncle

    If you don’t care about the British connection then the Chevy small block is cheap, easy to source and modify. It’s the no brainer as most already know.

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  9. Larry P

    The original Stag engine, when running right, is awesome. Nothing else has that same sound!

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  10. Roger Owen

    Ford V6 (Essex) was a common replacement in the UK. But the original V8 had a lovely ‘burble’ – I’d try and fix it or find another one.

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    LS motor of course ,LOL

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  12. DirtyHarry

    Triumph deserves a triumph motor. Make mine the 2.5 inline six with blower and fuel injection.

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    • grenade

      This, is really cool.

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  13. TVRMK3

    TR6 engine is to long to go in the engine bay. I would go with a 3.5 Rover V8 and 5 speed trans.

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    • Jamie Palmer JamieAuthor

      Actually, the TR6 engine fits perfectly, although you have to either use the front extention from a 2000/2500 sedan or an electric fan. The Stag came from that same platform.

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  14. wagon master


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  15. Mark P

    Ford 2.7L V6 ECO TECH. 325HP/364 LB/FT.

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    • grenade

      Nice choice with the Eco Tech V6.

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  16. Tim

    As built back in the day, the Stag’s engine did have a list of problems. But that’s all been resolved, and if the engine is rebuilt with all the known fixes, including a better radiator, then it gives good service. I’d choose to keep the car a original as possible by rebuilding the engine with upgrades.

    For those more prone to an engine swap, then I’d favor the 3.5 Rover/ BOP V8. It’s all aluminum and light, so it won’t upset the front suspension, balance and handling. Plus it still has that V8 sound, like the original. The TR6 straight six might be an easy bolt in, but it’s heavy, and way down on power by comparison.

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  17. Scott in San Jose

    As a lover of the looks of the Stag, this is a question I’ve asked myself. My preference is to have it original as they sound good and have had bad experiences with engine swaps.

    Question is who in the US is experienced in the rebuild and modifications? Also any idea on cost?

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  18. Bobsmyuncle

    Experience? That’s what manuals, and now the internet is for. It’s not magic it’s mechanics.

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  19. Richard

    GM 3800SC. with FWD drive train. Plentiful relatively inexpensive and pretty much bullet proof.

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  20. Madbrit

    Either use the tried and tested Rover V8 or if you want even more fun, go with the Chevy small block and be that little bit more outside the box. Once it’s no longer original, it doesn’t matter what you install, just do it for the fun factor…….

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  21. Van

    I had an original V8 car
    It was a great driving car but it had issues that can be resolved.
    I had a TR6 powered car and it drove fine although down on power.
    I dropped a ford 3.0 V6 into one and it was easy to do.
    I wanted to get a Subaru STI drive train.
    I didn’t check the measurements for fit but I’m sure it’s doable.
    But I’m insane.

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  22. Fred

    Where have I seen that front end before….oh yeah, ’73 Opel Manta!

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  23. sheffield cortina centre

    LS chevy or Toyota 6 or V8,here in the uk i’d go for the later due to price/avl.

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  24. jim s

    i like to keep things stock or close to it, but the motor is missing and a 4 speed without overdrive would not be fun. if i had a TR6 motor ready to use i would go that route and add overdrive. if not then either a rebuild stag or rover motor, which ever is less costly, and a 5 speed transmission. .

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  25. Steve B

    11. Slant 6

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  26. Casey

    Mazda rotary ;)

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  27. Murray

    To me the obvious choice for a transplant is the Rover Aluminium V8. Comes is 3.5, 4.0 & 4.6 capacities and there is a huge range of people in the UK making all sorts of tuning kits for this engines. Its quite easy to get 5.0 capacity out of these when combined with EFI and other goodies is enough to blow off all but the outrageous Good ole Boy American V8 options. Team the Rover with their fabulous five speed manual and you’ll have a fabulous, nicely balanced car which complete reliability.

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    • Ross W. Lovell

      Greetings All,

      Hey Murray……guessing you are from across the Pond. Here’s an epiphany for you…….

      THE ROVER ENGINE IS AMERICAN!!👍 BOP/Buick, Olds, Pontiac, sold the tooling in the 60’s to the Brits, you didn’t possibly believe the Brits came up with that bit of kit did you?😂

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      • Murray

        Here’s an epiphany for you Ross. You guys came up with the engine but decided early on it was not much good for the big heavy cars that you guys love. The Brits bought the design and were able to utilise the engine and develop the engine for use in the cars that Rover/MG/Land Rover were making. Many of which were sold back across the pond to Americans who preferred a more refined automobile than was being offered by American manufacturers. As for the Brits not being able to come up with “That bit of kit”, I’m sure they’d be more than capable had they needed to. They preferred to save their cash and buy it off GM who rather stupidly gave it away for peanuts. By the way I’m not from across the pond. Am from Down Under, third generation actually.

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      • Ross W. Lovell

        . Greetings All,

        Murray, just saying it wasn’t designed there. Not a Brit design.

        Personally, I think highly of the engine and the size is perfect.

        The one V8 that deserves praise is the Daimler 250. The amount of HP one of those can deliver is amazing when modified.

        Current Jag V8’s have suffered from typical Brit complexity, Four different chain tensioners, all made out of “space age” plastics, before metal was finally utilized. Nik-a-Sil coatings poorly applied in house, far from clean room status, it goes on.

        The Rover BOP unit that was sold to Rover was a good engine because we designed it but a great engine because we had high enough production numbers to work through long term issues BEFORE it was sold. That is usually the problem with many of the Brit cars. Jaguar walked through that gauntlet and somehow managed better considering they were part of BLC.

        The sale, not some of GM’s better decisions but the HP wars were on their way and this was considered not needed, unfortunately as I still would like to see sub 3.0 liter V8 platforms today.

        I took umberage at mentioning that engine as “yours” while using the Good Ole Boy moniker on the rest of the American iron, but nothing personal.😊

        Meanwhile, you a Ford or Holden man?

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      • Muz

        My garage/s currently house:-

        1937 MG-SA
        1945 MG-TC
        1997 MG-F (bought new)
        2012 Mini Cooper S John Cooper Works Edition – Wife’s car
        2014 Range Rover Vogue S/C V8 – My daily
        2016 VW Amarok Pick Up – Work Truck

        So am neither a Holden or Ford man, although I did buy new in 1979 A Holden Commodore SL/E 5.0 V8 4 Spd Man which I found to be a great car. GM lost the plot afterwards.

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      • Ross W. Lovell

        . Greetings All,

        Murray, the Holden/GM models in Australia are a complete mystery to me. Learning slowly as we had a strange Ford here some time back.

        Is it Holden when they do good and GM when they screw it up?👍

        I’m a Jaguar guy but our daily drivers are Subarus.

        Jaguars for us, range from a ’34 SS1 Tourer to a ’82XJS HE and some in between, most run and are legal.

        GM loses focus often chasing public whims of fancy and kissing up to whatever administration occupies the White House. More of a follower than a leader.

        These are the same group that put a Hybrid badge on a SUV that had a modified alternator that made 120VAC, absolutely nothing powered forward motion on the vehicle other than a conventional gas engine.

        Your SA, OHV or Flathead? Who made the engine?

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      • Julles

        Hey Ross. In my research I found that the Jag engine with the plastic tensioners were on the early XK8’s and XKR’s but in 2003 Jaguar fixed that problem and the engines are great since then. It is the reason the pre-2003 XK8’s and XKR’s are dirt cheap but 2003 and up you double the price. I had a stag or metal garage jockey for 15 years. I love the way it looked and sounded but we couldn’t keep the car running. We had engine, carburetor and suspension problems. I finally had to sell it because Van kept collecting other stags for parts and I was worried they were breeding. I would love to see the original engine really working in the car but I am so discouraged with it that dropping in a 2003+ Jag V8 sounds really nice as an acceptable fix and it was heartbreaking to see my baby languish in the garage and finally sold to put everyone out of their misery over it.

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      • Ross W. Lovell

        Greetings All,

        Julles, Jaguar went through either 3 or 4 different designs for the tensioner before they eventually decided on metal, according to their service bulletins.

        The price difference in engines has to do with the Nik-a-Sil debacle. It was a coating that was supposed to protect the aluminum bores in the block. It was improperly done. Jaguar blamed unburned gases from combustion. Oddly my 1980’s two stroke motocrosser had this, not an issue, and a fair bit more unburned gases in that design, being two stroke, not four,

        Engine replacement was the fix, hence the price difference.

        If you look on line, the process is linked to VIN numbers so it can be verified.

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      • Julles

        Ross you are bloody amazing! You stun me with how much you know. Obie-wan please continue to teach me.

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  28. John

    If the original is complete and can be rebuilt with the various updates, then by all means, keep it original. It will simplify life immensely.

    If the original motor is no longer complete, I’d consider a German Ford V6 2.6 or 2.8 from a Mercury Capri. It would provide very nice performance and its longevity is unmatched. They are available at attractive prices.

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  29. Murray

    Never been a fan of V6s. Always seem to me to sound like a V8 with two plugs missing 😀

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  30. Larry P

    Hmmmm, this is making me think I should sell my ’73…

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  31. zaphod

    The originals had timing belt tensioner problems.
    Most of the one I have done have had the Rover 3.5 or the Land Rover 4.0 liter transplanted. Stags should have been better than they were but, as anything British produced during that era, they were built for export and what the Brits thought the rest of the world wanted.

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  32. dj

    I have a GM 4.3 that the previous owner went wild and spent tons of money to make it haul butt in an Astro Van(don’t ask me why because I don’t know). It would work great in this car.

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  33. Crazydave

    The answer is ALWAYS the SBC

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  34. Van

    The original engine produced close to 145 hp.
    Find the lightest engine you can to do that.
    That’s like improving brakes, stiffening the springs, and improving weight distribution all in one shot.
    I’m just saying.
    Maybe Hyabusa!

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  35. Keith Matheny

    Ummm,,,. How about the SHO motor I have at the garage, 300hp? Just turn the intake around to face the front, add tuned exhaust for a sweet sound. Ya, I like it!
    Always liked these, Giovanni Michelotti designed body and an upscale British interior, roomier than my Spitty, and much softer ride, lol.
    Would be a rare sight to see another coming.
    Ya, 300hp and a nice t56, poach a stronger IRS if needed, would do just fine in this!
    But, now, NJ is not the place where I’d expect to find good bones to start with.
    PPI is mandatory on this project I think. Bring a porta lift.
    $3k would be tops to start with this much work, just my opinion. Money talks, etc.!

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    • Van

      Like your choice

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  36. Bill McCoskey Bill McCoskeyMember

    Had a wealthy customer here in the US with 3 British cars in Barbados, I used to fly down to his $10 million estate for a week at a time & work on the cars until about 1998. They were:
    Mini-Moke [Assembled in Portugal]
    Morgan +4 [the only one on the island]
    Triumph Stag.

    The stag never ran well, and had constant overheating problems, and because the use of anti-freeze is almost unknown in the islands, this resulted in head gasket leaks. We didn’t have the facilities anywhere on the island to handle the removal of the heads, and the engine was too far gone to repair. I had a TR-6 that had been fully restored before being badly burned in a building fire, but the engine was perfect. We sent the engine down to Barbados on a pallet, and it was an easy install, needing no modifications except for an electric fan in front of the radiator.

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  37. Van

    I still say cut the body of a WRX-STI slide under Stag be glad it has a roll bar.

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  38. Terry Hunt

    Well to answer the question properly.. I just bought this car and it getting the original Stag engine!!

    Yes really!!

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    • Jamie Palmer JamieAuthor

      Terry, be sure and update us! Congratulations on the purchase!

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      • Terry Hunt

        It will be a few years but I’ll try..

        My website is It will be on there soon. My 4th restoration and my retirement project. The next year or so is collecting parts, I doubt I’ll start anything yet.

        I think that all these engine choices are great in theory but the Stag does not pull high prices, restoring the body and interior alone would push the price of any of those non standard engine cars over its worth, the engineering needed to convert is not trusted by future buyers, they just won’t buy.. The only way I can restore this car and expect at least most of the investment back in the future is to keep it original, and do everything myself.

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  39. EDWARD

    Try the Ford 260 V8 punchy and supercharged would be overpowered.

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  40. stagman

    Mine was outfitted by the original owner back in the 70’s with a 327. Although now it’s a 4-bolt 383 in hindsight if I could not refit the original motor I’d go with an LS6 or a last generation Rover 4.6 w/5 speed and trick to tears.

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  41. Terry Hunt

    One Triumph V8 engine ready, Gearbox rebuilt and converted to overdrive. I am planning on electric water pump and a header tank to help with the cooling. Starting the body (which is remarkably rust free) in the spring.

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  42. Terry Hunt

    Its looking a bit different now! Media blasted and a coat of epoxy and I’m sorting out the areas that were attacked for a gearbox replacement. Its definitely a solid car but there is some rust in the rear seat pan that needs sorting.

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  43. Joakim

    Looking great, Terry, good work!

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  44. Terry Hunt

    Its back on its wheels… Engine in soon. I will add an electric water pump and have mounted a trigger wheel for future improvements, Hopefully this is just months away now..


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  45. Terence Hunt

    cant remember how to post pics so lets try this

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