Category Archives: ’73 Triumph TR6

'73 Triumph TR6, Build Projects

British invasion, The ’73 Triumph

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After declining to rebuild my neighbor Wendy’s Triumph TR6 for a few years because I was too busy building these old trucks, she finally approached me with an offer I couldn’t refuse. “Give me $250 and send another $250 to my favorite charity, and it’s yours.” Thus began a two year rebuild… not at the Barn but in my garage at home.

My plan for this narrative is just to post pictures of the process, with captions. I’m sure that there will be posts dedicated to specific problems and solutions, but this build story will be heavy on photos.

Here is the current state of the TR6 as of Fall 2021…

Next guy can paint it… I have grandkids, and they don’t use the doors
California Special… no heater or top
Now it’s a “fuelie”… Patton TBI system
Short drive in the TR6 on a nearby twisty road.

Enjoy the (mostly) photographic narrative of the two year journey. Click on the Triumph link in the table of contents at the top or left side of the page for a complete archive of posts. There is a list of vendors we used on this project in the Stuff We Like post.

'73 Triumph TR6, Build Projects

1973 Triumph TR6 rescue and restoration

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Here are a few pictures depicting the state of the Triumph after sitting outside under a fabric car cover for twenty years… thank goodness it resided in Southern California. But it was truly a rodent hotel.

Just to get it home I needed to buy two new wheels and four tires. And find a locksmith… the keys were missing and the steering was locked.

Clearly we are looking at new floor pans in the passenger area, as well as the trunk. And pretty much everything else!

One word of advice for you when cleaning out an old car that has been host to rodents… MASK! The trunk, for example was at least four or five inches deep in droppings and twigs and nut shells and dirt. Gross.

I was somewhat careful about wearing a mask as we filled a garbage can with rodent droppings and shells and whatever the heck all that other stuff was, but not as careful as I should have been. My lungs have literally never been the same since that original cleanup. This is serious advice, heed it, please! Best practice would have been a good painter’s mask with dual filters, reasonably priced at Harbor Freight. I did utilize one, but there were occasions when I just wore a paper or cloth mask… that is not sufficient.

'73 Triumph TR6, Build Projects

Triumph TR6 restoration: Removing the engine

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Added strength because hoist is fully extended
Making sure I could lift it high enough
Engine was removed with transmission then separated
There’s a hole in my Triumph
Head removal
Lighten the load for the engine stand
Engine removal crew: wife Linda and our friend Ellen Lawson
Old friend and racer Chuck Burnett “supervising” engine removal

The engine removal was straightforward. I left transmission and cylinder head attached, but removed manifolds and alternator, disconnected driveshaft, wires, and hoses. The head was stuck on the block so we used the hoist to separate it from the block, making sure it was pulled up evenly. Because the hoist was fully extended to the 1/4 ton hole, I added a reinforcing square tube all the way to the hook, which required drilling a hole for the 1/4 ton pin.

'73 Triumph TR6, Build Projects

Triumph TR6 restoration: Engine stand installation

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Will this work?
1/4 plate was beefy enough
Engine mount used as a template for holes
Yep it works, easy to rotate the engine
Side mount worked out well for the TR6
Piston tops and cylinders looked decent

The other engines I’ve rebuilt were always mounted onto the stand at the rear of the block. After reading what other TR6 owners had done, I chose the side mount. This worked out very well, and the 12″x6″ quarter inch thick plate was plenty strong… no flexing or movement at all.

'73 Triumph TR6, Build Projects

Triumph TR6 restoration: disassembling the engine

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Measuring the bores
Noting the position of the oil pump drive slots
Piston/rod assemblies coming out
Carbon buildup
Lots of combustion chamber cleanup to do
Head is stripped except for guides
Rotating assembly gone, block almost ready for machine shop
Hmm… how much can I increase the compression?
Cleaned up piston, but HDS wanted to bore the cylinders, so these were not used

Well, everything looked as expected for an engine that probably hasn’t been freshened up since it was manufactured nearly fifty years ago. The cylinders looked fine to me, as did the pistons, but my machine shop of choice HDS/Carquest in San Marcos thought otherwise. Casey, the owner, knows what he’s doing. I absolutely trust him. Before getting the block and head over to him for the serious business, I decided to clean up the combustion chambers, ports, and connecting rods myself, as shown in subsequent posts.

'73 Triumph TR6, Build Projects

Triumph TR6 Restoration: Engine prep before taking it to the machine shop

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So much fun with just a rod and a file
Removing metal to get rid of sharp edges and ridges
Got rid of some weight, too. They’ll be peened later, at HDS
Smooth, and now they each weigh 640 grams
Minimal work getting rid of sharp edges here, too
Nothing drastic was done in the ports
Just a little cleanup, imagining the airflow
Modified intake manifold
The original
Ready to measure combustion chamber volume

Easily one of the most enjoyable parts of my rebuild was the file work on the connecting rods. I have read the stock connecting rods weigh in at 684 grams, which means I filed about 44 grams off each. My aim wasn’t lightening them, though, just wanted to remove any sharp edges, grooves, etc., that might be a point of failure by propogating cracks. HDS would restore surface strength with their peening process.

With the ports and manifolds, my goal was just to clean them up a little to aid the flow. I would advise being very careful around the valve seats… make sure you leave enough material to insert new seats and still have a nice smooth transition to the port with no big pockets behind the seats. I tried to be very conservative there.

In the combustion chambers, I was again just focused on removing sharp edges to eliminate hot spots and smooth things out a little bit. It comes at a very slight cost in terms of compression ratio since I was making the chamber a little larger in volume. I was asking HDS to lop .140 of the heads, so it was of no concern at all.

'73 Triumph TR6, Build Projects

Triumph TR6 Restoration: machine shop work performed on the engine

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Note all the holes drilled to balance the assembly
Looding up for the trip to machine shop
More goodies for HDS
Bored and waiting for those new pistons
Camshaft will now spin in bearings
Rear view
So clean
Ready for assembly

I brought the engine block and cylinder to head to Casey down at HDS Autoparts & Machine Shop in Escondido, California. Along with those heavy pieces I dropped off the following:

GP3-110 camshaft; ATI Super Damper; lightweight steel flywheel; new clutch and pressure plate; hardened valve seats; new valves; ARP head studs — all from Goodparts. I brought Casey my matched-weight set of County .020 pistons/rings/pins from Wishbone Classics. I also brought him my crankshaft; new timing gear; and my lightened 640 gram connecting rods. And probably other stuff I’m forgetting. Anyway he got the entire rotating assembly from damper to pressure plate.

HDS cleaned and magnafluxed the engine; bored the block and installed cam bearings; bored the cylinders .020″ and surfaced the block; peened my modified connecting rods; kissed the small end of the rods; modified the rods for ARP rod bolts; installed cast iron valve guides and hardened valve seats; polished the crankshaft; machined .140″ from the cylinder head; and balanced the entire rotating assembly. The compression ratio should be in the area of 9.5:1 with the milled head.

With the matched piston and rod weights, there wasn’t much to do on the rotating assembly except for the pressure plate. As you can see from the photo above, quite a bit of drilling (metal removal) was needed to balance that puppy. Should be smooth sailing, especially with the inherent smoothness of the six.

Postscript: the spec I gave Casey for the valve guide height was from the factory manual. That was a big oops, explained in the engine assembly article later.

'73 Triumph TR6, Build Projects

Triumph TR6 Restoration: body removal

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Bringing the leverage
I took lots of photos to jog the memory later
Don’t want the body to fold in half
No new holes or welding in this solution
What I envisioned
And what I ended up building
Front floor mounts
Seat belt threaded hole
Engine hoist, wife, and self and it’s off

Separating the body from the chassis was a momentous occasion, and pretty straightforward, with the engine and transmission and the passenger floors and gas tank already removed. One of the online sites, can’t remember whether it is TRF or Moss, has a good illustration of all the bolts securing the body, and that was helpful for removal and re-assembly. Of course there are brake lines and fuel lines and other bits that need to be undone, as well.

We used our engine hoist to do the lifting, anchoring the chains as shown in the photos. I built a stand with wheels so that the body could be moved around in the garage. The stand also allowed me to work while standing up inside the engine bay or passenger area when necessary. As you can see in the pictures, I utilized the door hinges and latch holes, along with a couple other existing holes, to brace the body so it would not fold and create problems later. I really didn’t want to go to the trouble of welding and and then grinding off the braces, nor did I want to drill any holes.

'73 Triumph TR6, Build Projects

Triumph TR6 Restoration: reparing the frame

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Right front fulcrum pin bent
Shock tower factory weld broken loose
Tie rod distance piece squished out of shape
Fulcrum bracket bent
$150 porta power from Harbor Freight

As I looked over the frame after removing the body, I was really pleased at the absence of rust and absence of cracks in the usually suspect areas. However, upon closer inspection it was obvious that the car had taken a hit in the right front corner. The direction of the hit seemed to be from the right front wheel on a vector through the driver’s head, as if it had been driven into a culvert and struck something immovable.

I thought about taking it into a body shop that had frame straightening equipment, but ultimately decided that a little work with a porta-power hydraulic ram would solve my problem. Well, that along with some new parts and a bit of welding. I was already planning on replacing every bit of the car that could possibly be worn, so adding few more pieces to replace bent parts was no big deal.

The porta-power worked great pushing the shock/spring tower back to where it belonged. We’re only talking about 7/16″ but the frame is a little springy so it had to be pushed a bit further than that to allow for spring back. I replaced both upper fulcrum pins (left and right side of the car), welded the shock tower where it had come apart, and then trusted that I could get the alignment right when it all got bolted back together. And it worked out perfectly.

'73 Triumph TR6, Build Projects

Triumph TR6 Restoration: frame and suspension rebuild

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Home made spring compressor
The bottom half
Worked like a charm
Rear suspension off
Cleaned up front front wishbones
Painted and rebuilt
Test fitting
New rotors
Adjustable swingarms test fit
Adjustable fronts and re-valved levers
Shorter and stiffer springs
Engine hoist is multi-purpose tool
Primer was followed by black frame paint
Back together and ready for alignment
Setup for rear camber measurement
Rotated horizontal for toe adjustment
New brake lines and fittings
Rebuilt rear drum brakes
More stopping power

Rebuilding the suspension and restoring the frame was very satisfying, and it feels good to have all new bushings and bearings, brakes and brake lines, shocks and springs, and a fresh coat of paint on everything.

The alignment process was simple enough. First I found the centerline of the car and then set up a couple parallel strings running along the length of the chassis, a little wider than the car’s track and running through the centerline of the wheel hubs. I used a length of 1/4 thick aluminum bar to represent the wheels. With the bar vertical I adjusted the camber angle. With the bar horizontal I was able to adjust the toe. I set it up without the springs installed so I could raise the suspension to where I estimated they would be if the car was sitting on the ground. Any additional adjustments will come after the car is driven.

In addition to replacing all the bushings, nuts and bolts, and worn out stuff, I replaced both upper fulcrum pins and the passenger side vertical link. New parts also included 390 lb front springs and 470 lb rear springs from Goodparts, which lowered the ride height by an inch and stiffened up the ride. GAZ adjustable shocks in front and rebuilt lever shocks in the rear with custom valves to suit the stiffer springs. World Wide Auto Parts did the rebuild of the lever shocks.