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This is my GT6 V8 project. In future posts, I will provide some history and detail (including pix) on how it was done in future posts.


Owner: Al Gunnarson

Location: Victoria, B.C. Canada

Model: 1972 Triumph Gt6 Mk3

Weight: 1990 lbs.

Built by: Owner (35 years)

Youtube: https://www.youtube.com/watch?v=k1m0alKUHYY

                 Google GT8 Video 001 if like does not work.

Engine: Rover 3500 cc V8 (SD1) High torque starter, Pertronix distributor, NOS Rochester 2 barrel carb and Buick manifold.  Buick V6 water pump, machined crank damper for pulley to match Chevy water pulley. Current output dyno’ed at 200 ft. lbs. torque at rear wheels. July 2016 - updating to Edelbrock 500 cfm on stock Buick 4 barrel manifold, Spectre 4†low profile fresh air intakes system and a 24 lb. steel flywheel.

Exhaust: D & D Fabrications block hugger headers, Single 2.25 inch exhaust and Flowmaster muffler.

Cooling:  Afco Scirocco style aluminum radiator (overall dimensions - 21.5†wide, 13.25†high, 3†thick) with single electric puller fan.

Transmission: LT77 5 speed manual transmission from 1980 Rover SD1 V8. Remote shifter from Sherpa van.

Differential: 1972 Datsun 240Z (R180) (3:364 ratio) with Datsun half shafts.

Front suspension: Spax adjustable shocks, Spitfire springs 25% uprated and lowered 1â€.

Rear Suspension: Stock lower wishbone layout with additional spring added and Corvette shocks mounted to earlier style mount holes on frame.

Brakes: Stock Gt6

Wheels and tires: 13 x 6 Minilite style mags, 175 70s 13 Radial T/A tires, wheel studs uprated from 3/8 to 7/16 inch.

Body – All rust removed and panels replaced. Rockers removed and inner panels re-formed with double folded 1/16 sheet steel for additional strength. Inverted louvers from TR7 cut into hood for additional cooling. Hush Mat on interior floor.  Body raised on frame for additional engine clearance, minor notching for engine clearances at firewall. Gas struts for hood support.

Frame – minor notching and boxing, additional bracing on engine mounts, suspension turrets, trans mounts and diff mounts.

Electrical:  GM Alternator, additional fuse block for added for fuel pump, cooling fan, lighting relays. Alpine stereo with Alpine amplifier, Scosche 400 watt sub amplifier and 8†Sub-woofer in custom box. Additional instruments include oil temp, oil pressure and vacuum gauge. Lower late model Mustang battery mounted in trunk.

Status: V8 Conversion completed in 2013 and the car was driven until July 2016. At that time engine was pulled to fully inspect conversion after three years of driving and to complete performance upgrades.


The engine is out of the car for performance upgrades In future posts I will provide detail of the initial V8 swap and talk about some of the improvements planned from lessons learned while driving the car for the past three years. Let me know if something n particular interests you so I don't miss anything.

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I've come across that video before! Very nice car :)


I think the PO of my blue Spitfire had a similar idea, but ended up cutting a massive hole in a perfectly serviceable bonnet and glassing a scoop on :S


What performance mods are you doing on the RV8? As you're on the other side of the pond you should have access to the alloy Buick 300 heads which flow quite a bit better than the stock Rover heads.


Looking forward to updates :)

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GT6/Rover V8 swap history and proposed updates.


This project began 35 years ago in 1981 when I purchased a very rusty and worn out 1972 Gt6 Mk 3. At the time, I was 26 years old and possessed the most rudimentary of tools and space. (Primarily some spanners, large hammers,  an oxy acetylene unit and a double carport). Over the next year, I replaced or repaired all of the rusty panels and did a frame off restoration. This included installing a 2500 cc TR6 motor and transmission. I also installed a 240Z differential and half shafts. But, that is a different story.


I drove the car for almost 20 years and really had a lot of fun with it. During this time, I rebuilt the engine and in the process decked the block, skimmed and ported the head and installed a Kent TH2-6 cam and twin 1 3/4†SU carbs. I parked the car in 1999 and focused “too much†on work.

 I would be happy to share the challenges of the initial TR6 drive train swap in a different thread.


Flash forward to 2011. I had recently retired and could focus more on my “preoccupation†which was restoring the GT6. By this time, I had built a fully equipped shop and accumulated all of the necessary tools.


The re-restoration of the car was a very interesting process. Many restorers curse the DPO (devious previous owner) during restorations. I found myself looking at a younger version of me in the mirror and alternating between “you idiot†and, “that was f...ing brilliantâ€.  It was a very interesting process. 


When it came time to install the power plant, the plan changed. I had purchased a nice California 69 Tr6 that I was also restoring and decided to use the Tr6 engine from the GT6 in that project. I had also picked up a low mileage 1980 V8 Rover SD1 along the way.


While it was my intent to also restore the SD1, a fellow came along and made a great offer on the body that I had stripped to bare metal and de-rusted. This left me with a very nice 3500 V8 with only 100,000 km on it and a rebuilt lt77 5 speed. 


After some quick measurements, I decided it “could fitâ€, if I did not go too crazy with power. I was committed to not cutting a hole in the hood. This proved a real challenge, but seemed possible if I stuck to a 2 barrel carb, block hugger headers and Pertronix distributor.


I drove the car for three years without any issues. The frame and differential were definitely up to the task. There was lots of power, but I felt it was “running out of steamâ€, above 4000 rpm.


This brings us to the present. I have decided to pull the power train out. I don’t want to go overboard with the power as I do not want to do extensive mods to the frame, and definitely do not want to cut the bonnet.


The plan is to freshen the engine up with new seals and gaskets, new timing gears and chain, 4 barrel Edelbrock carb and a fresh air system. In addition, I have purchased a light flywheel (24 lbs. as opposed to 34 lbs.). This should provide more acceleration with less of an “inertial shock†to the frame and drive train when shifting fast. I simply want a very reliable, smooth driver. A long legged cruiser that will light the tires up at will.


With the car now apart, over the next few posts, I will provide some of the detail (and pix) required to get the engine and drive train into the car and under the hood in the first place. So, the focus of my challenge is to drop  the engine low enough to accommodate the four barrel and fresh air system and still have comfortable ground clearance.  What is motivating me is the knowledge that the swap is more than worthwhile and that it all works.




I want to go from this




to this




And so, it begins....


Comments and suggestions are welcome. Stay tuned.


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Hi Richbike,


Good question.


While the car is pretty fast from the torque it produces ( almost 200 ft lbs @ 2400 RPM), the horsepower remains modest and flattens out at 4000 rpm at around 120 hp at the rear wheels on the dyno. The A/F ratio is pretty much spot on. The issue is the small 2 barrel carb and a very restrictive air filter, which drops down around he carb and is pressed very tightly to the bulge in the hood. The only air getting up there is pretty warm also.


Here are the Chassis dyno results. The most recent is a bit higher, but not much. Just can't find it.





The carb is pretty restrictive and is rated at under 300 cfm. It's small size did facilitate the original build.



Also, I wanted to capitalize on the cars lightness and switch up to a light flywheel (24 as opposed to 34 lbs).

Having such a heavy flywheel in such a light car, really gives it a "jump" forward, but I want to exchange this shock to the drive train for even faster acceleration. (And yes Nick,  it will bark the tires in 4th....but not 5th gear.


Final reason, the engine, while having only 117,000 km on it is 36 years old, and leaks a bit of oil when it sits. Something it never did before. I have dubbed it "the Blackbird" as it only leaks when it is cold. A product of alloy block and steel rear main seal retainer having lost the bonding seal...we will see.  This will also give me a chance to change the timing chain and gears, which are probably getting a bit sloppy.


There....you have it.



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 I have had a bit of bad luck and I have to stay out of the shop for a few days. A piece of lathe swarf decided to wrap itself around the end of my ring finger and almost took it off. makes me wince just thinking about it. Eight stitches have kept my finger intact and so far...without infection.


So, notwithstanding my typing with a huge bandage on, ( I apologize for any typos)......I have some time to talk about the initial work to get the Rover into the GT6. Over the next few posts, I will include the Datsun diff, exhaust, frame mods, body mods, suspension and engine mods. (and anything else you would like to know about it)


When I planned the swap, I wanted to keep it "conservative" to see how the frame, diff and suspension worked with the V8. A limiting factor with the car is hood clearance,even with the GT6 bulge. I did not want to change the look of the car. I was also reluctant to drop the rack lower as this does cause unacceptable bump steer.


One solution was to move the engine rearward, but the LT77 gearbox will only go so far back into the narrowing frame due to the width of the box and the clutch arm. Also, I wanted the gearbox lever to be in the stock position and this was perfect with the Sherpa van shifter.


With the engine almost touching the steering rack, there was barely room for a ten inch K an N filter on a home made drop base. A NOS 2 barrel Rochester from a Buick 215 and stock Buick manifold gave the lowest option.


Still, there was very little room for air to enter the carb due to the hood being so close to the air filter and the limited clearance within in the dropped filter housing.




When I did the TR6 engine swap, I initially changed out the GT6 diff for a Datsun 240Zs in 1981. The first one was a 4:11, which proved too low geared with the TR6 4 speed.


In 1982, I replaced it with a 3:64 which is pretty close to stock and is perfect with the LT77 five speed.


The diff was prepared by fabricating a spring saddle and welding it to the top of the diff. While I was uneasy about this, I had it done by a certified welder and there has been no hint of trouble for 35 years.




I initially bolted two new rotoflexes to the diff (GT6 flanges bolt right on). After a couple of years of spirited driving with the TR6 engine, the rubber rotoflexes started to tear up. The solution was to put a flange onto the rear axle and install a set of Datsun half shafts.




These half shafts must be turned end for end to clear the frame and are a bit long, so the inner shaft needed to be shortened and the C clip moved inboard to keep the inner shaft from hitting the end of the outer casing.


A front and rear trans mount were fabricated and the frame bushed for the long bolts that hold them on. The diff angle can be adjusted by putting shims between the saddle and the diff, or the mount and the frame. to raise or lower the diff nose. The driveshaft is MGB (Spicer) with a Spitfire rear yoke. This is the same pattern as the Datsun diff.










My buddies came over to the "happy dance" with me after the initial engine fitting and to help with the first trial fit of the body.


Well, that's about it for now....gotta give my finger a rest...


More to come.


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I like the idea of welding on the spring mounting to the body of the diff. Is it cast iron or steel? If it's iron it might be a bit beyond my capabilities to weld at home :S


Also, can you remember roughly how much interference there is between the protrusion in the bellhousing and the chassis if you'd put it so that the frontplate of the engine is behind the steering rack?


Just wondering if there's a possibility to notch the chassis and reinforce the opposite side of the rail to allow you to mount an LT77 further back...

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Hi Biturbo,


The diff is cast. That is why I had a pro do it. I believe he said the rod he used  had nickle/bronze in it, but that was a long time ago.


The biggest  protrusion between the bell housing and the frame was the clutch lever housing. I recall feeling a bit uneasy about cutting in further than I did.

Here is a pic of the notch I cut out and boxed. With this, the pan hangs over the rack by about an inch.





There are further areas of concern in moving the engine back. As the LT77 moves back into the frame, things become very tight and further notching is required.




Also, any further back and you will have to do much more serious notching of the firewall than I did. This also changes how where your gear lever comes out and how the trans cover fits.




Hope this answers your questions.



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Perfect :) exactly what I was looking for :)


As (if it works alright) I'll make a habit of welding my bodyshells to my chassis' I should have a bit more 'chassis rail' to play with when notching it.


One of the future ideas for my Spit6 will be a Rover 2600 engine and LT77 'box which will probably need it to be a bit further back than yours does, but would help with bulkhead clearance issues.

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Greetings from the colonies! While I convalesce, I will continue with some of the detail on the V8 swap.


Exhaust –  When putting in this system, the design was limited by the design of he GT6/Spitfire.  In the end, it did come together with sufficient ground clearance. Going with dual ed


It is very fortunate that the pipes fit, one size going into the next until it sized up to a 2 ¼†single exhaust. I did have to make  a couple of trips to the local muffler shop for some bends on the long pipe between the frame rails as well as a couple of swages.


 The system begins a set of  D and D Fabrications “block hugger†headers. These did leak a bit at the flange at the head and had to be built up and machined for a tight seal.


I purchased their "high torque" starter which gives lots of clearance for the exhaust down pipe and avoids any heat issues with the solenoid.


A couple of swaged "L" bends slipped tightly onto  to the down tubes between the frame rails. This did require some minor grinding on the frame flanges. These L pipes lined up perfectly with the old SD1 collector. With a bit of bending of pipe, it tucked up nicely into the frame. (Again, I did need to trim some frame flange for clearance).





The pipe had to kick a bit off to the side to clear the bottom of the trans. Thankfully I had mounted the trans in a V mount rather than from the bottom.





The nice thing is that when I lower the motor to fit the new induction system, the s header pipes can be shortened and the L shaped down pipes can slip further up the headers..








The diff mount was notched tor clearance and a Flowmaster 40 muffler provided the sound I was looking for with no resonance in the cockpit.


It would have been nice to put a dual exhaust onto the car, or even a larger pipe,  but these would have been much heavier and would not have provided the same ground clearance.


More to come.

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