Triumph Stag : Cylinder head removal

The Triumph Stag’s cylinder heads aren’t known for their longevity or strength…

And our man in Detroit has found this out to his cost. But thanks to the right specialist, he’s a happy man again with a working engine in his stag again.

Words and photography: Richard Truett

Total Flow saves the day

Steve Sanchez, owner of Total Flow Products, with Richard Truett's Stag cylinder head.
Steve Sanchez, owner of Total Flow Products, with Richard Truett's Stag cylinder head.

LAST fall I bought a 1973 Triumph Stag that had been stored in an Indiana barn since 1987. I got the engine running barely well enough to propel the Stag into my warm garage for the winter. My plan was to have the car roadworthy by spring. I performed a compression test and found 7 of the 8 cylinders were all within 125-140 pounds. But one was a disappointing 105 pounds. That meant the heads were coming off.

And you know what that means when you are dealing with any version of the Triumph overhead-cam engine: There’s a good chance a stud or bolt will break, leaving you to deal with the frustrating nightmare that goes along with that. But I got lucky. Using the special stud removal tool you buy from Stag specialists, I was able to remove the heads with no trouble. I saw a thick crust of black carbon on the piston crowns and combustion chambers, but nothing structurally wrong.

So, I took the heads over to my local machine shop — the same one that built my TR7 Sprint engine a few years ago. — I wanted the heads checked for straightness, cleaned and the valves inspected. A week later came the call you dread when you own a Stag. ‘Mr. Truett, you need to come down here and have a look at these heads. I can’t really explain what’s wrong over the phone, you just really need to come here and see it.”

My heart sank. This didn’t sound good. When I saw the Stag’s heads, all cleaned of carbon, I couldn’t believe my eyes. Chunks of metal were missing from the combustion chambers. During the long storage, moisture eroded the aluminum and left deep pits in the metal. One of the valve seats looked ready to fall out because there was so little aluminum around it. On the gasket face or deck of the heads, more metal was missing where moisture had eaten it away. The shop recommended I buy a good used set of heads.

But that’s no easy thing with a Stag. With a total production run of around 26,000 Stags and only around 2,400 ever sent to the United States, these unique cylinder heads aren’t exactly common. And when a good pair does become available on eBay or elsewhere, they don’t go cheap. Now I understand why so many Stags have Rover, Ford, Chevrolet and other engines under their stylish bonnets. Some people just find it easier to install some other engine instead of dealing with the Stag’s unique, some might say, finicky OHC engine.

But installing some other engine in a Stag means you have to essentially re-engineer the car. Not only do you have to buy the new engine, but you need a new transmission, new driveshaft, radiator, etc. There will be all sorts of modifications to make such things as the power steering work, and to get the exhaust to fit. Also, the replacement engine isn’t going to weigh the same as the Stag’s engine, so the car’s handling is going to be affected. And even if you get all that stuff sorted out, you’re Stag‘s value probably will be severely hurt because the car is no longer original. For me, the only choice was to get the Stag heads repaired.

So, I called a few gearhead friends who have built their own performance cars. They know where all the great shops are in Detroit. There are hundreds of unique businesses catering to the auto industry that are tucked away here in quiet industrial parks. Many of these businesses don’t advertise much because they specialize in something very specific. They are so well known for what they do that people seek them out.

Total Flow Products in Troy, Michigan, just north of Detroit, is just such a place. I ended up there on the recommendation of Mark Bradshaw. He’s a GM engineer friend of mine who had his TR8 heads built and modified at Total Flow. Bradshaw was thrilled with the results. My Stag’s heads needed major, radical surgery if they were going to live. And Total Flow was really the only place capable and willing to do the job.

When you walk into Total Flow, you see an immaculate, well-lighted machine shop with shelves and workbenches loaded with hundreds of cylinder heads. There’s also a lot of expensive machinery, Much of it is computerized, and it is manned by a young, friendly, knowledgeable and enthusiastic crew.

When it comes to complex problems with cylinder heads, Sanchez is not the kind of guy who backs down from a challenge. He’s seen and fixed it all — valves embedded in combustion chambers, damage from shattered pistons, broken valve springs, leaks of every variety, warpage beyond imagination and more.

Most of the work done at Total Flow involves creating perfect heads for dragsters, stock cars and other super high-performance race engines. This is a company that can custom design and manufacture complete cylinder heads from solid blocks of aluminum. Total Flow takes in cylinder head work from engine builders and machine shops from all over the world. The company has earned a reputation for turning out flawless work. I found out later that Total Flow had already done work for me. A few years ago when I built my TR7 Sprint engine, my machine shop shipped the special 16-valve Triumph head to Total Flow where it was ported and polished and given a valve job. The work was beyond excellent.

Sanchez looked over my Stag heads carefully and pronounced them ‘rough but savable.” Sanchez said he believed the heads could be made better than new, not just repaired. The tone of his voice was reassuring. I felt he was enthusiastic about the job and really wanted to do it. My heads wouldn’t be some annoyance he’d get to when things were slow.

Sanchez told me his plan for rebuilding the heads, and I liked it. First, he would take precise measurements of a good combustion chamber with one of his computerized machines. Then he would weld all new metal into the areas where the aluminum had been eaten away. Finally, using the measurements he’d taken, new combustion chambers would be carved out of the fresh metal by a computerized cutting machine. When it was all done, each combustion chamber would be exactly the same size and shape. This job would not be cheap and would not happen quickly, Sanchez warned. But he could do it if I was patient. With the Stag tucked away for the winter, I said let’s do it.

What Sanchez needed from me now was not a huge pile of cash, but sixteen new valves, sixteen new springs and keepers, a set of head gaskets and all the factory literature on the engine I could dig up. He also wanted the camshafts. The job had to go slow, Sanchez explained, because of the high heat the heads would be subjected to. Too much heat, Sanchez said, could cause the aluminum heads to warp. So, only a small amount of welding could be done at a time, perhaps only a few minutes a day. The heads were kept wrapped and at a consistent temperature. The cams would be used to ensure that no warpage occurred.

I stopped in once or twice during the time it took to complete the job. Blobs of new aluminum, shaped like dollops of mayonnaise, were in the combustion chambers, I could see now that this repair would be a very labor intensive job.

After about 90 days, Sanchez called and said the heads were ready. When I arrived at Total Flow, I couldn’t believe these were the same Stag heads. First of all, they were totally spotless. The metal — inside and out — shined like new. Looking closely at the combustion chambers, I could not tell there had been any welding. More than that, I could see written in black magic market on the valves and sides of the heads that precise measurements were taken. All the tolerances and distances of the valve seats and guides were consistent. Even the cam tappets were checked, measured and matched to each valve. The heads were checked and inspected in just about every way.

Total Flow made a special jig to mount the heads for pressure testing. Both sides of the heads had been resurfaced to ensure a flat fit for the intake and exhaust manifolds. Each head sported all new helicoils and freeze plugs. A more robust set of valve seats with thicker metal than the originals had been installed. But what really got my attention, though, was the surface of the combustion chambers. They were perfect.

Total Flow doesn’t see many Triumph cylinder heads, of course. But you’d never know that by the finished job. In more than 25 years of restoring Triumph sports cars, this was far and away the nicest work and biggest mechanical miracle I’d ever seen performed on Triumph components.

Sanchez was rightly proud of his crew’s work. It was not an easy job and certainly not a job for a run-of-the-mill machine shop. In talking to Sanchez and explaining the delicate nature of the Stag engine, he decided that the work he did on my heads did not have to be a one-time thing. Now, he wants Total Flow to be the world’s number Triumph Stag head repair shop.

All the data from the work done on my heads has been saved in computers. It’s not an exaggeration to say Total Flow now knows Stag heads inside and out. Every possible measurement of my heads was taken. The computer program that carved out combustion chambers on my heads can now be used on other sets of Stag heads. The good news, Sanchez said, is that any Stag owners who come after me will probably get similar repairs done cheaper. Most of the prep work and set up work needed for my heads can now be duplicated easily. And now that Sanchez knows the quality of the aluminum used in Stag heads, the job can probably go a bit quicker. Still, you won’t get the heads back until they have been checked and inspected in just about every way and reassembled and then checked again.

‘First, we make sure everything works mechanically and all the fluids stay where they are supposed to,” says Sanchez. ‘In other words, no oil leaks, no oil drainback holes draining into water or the outside of the head.”

As for my heads, Sanchez said: ‘It took us a number of days to put the right amount of heat in the heads and do the right amount of welding. And then cooling them slowly. Every day we kind of went through that slowly a little bit at a time so we didn’t overheat and warp the heads. Those heads were rough.”

I wondered how my heads could have possibly disintegrated. Sanchez’s theory: ‘The engine probably had water in the cylinders and it sat in a place where the temperature probably changed 100 degrees in a year. What you brought us was oxidized and eroded ‘70s aluminum from Europe that we didn’t even know that much about. Aluminum that old has a lot of impurities in it, a lot of dirt compared with what we have today,” Sanchez said.

A neat thing happened as Sanchez got into the project. As he took a close look at the Stag heads, Sanchez found some pretty nifty design work, especially in the intake and exhaust ports. He says the design is very advanced for heads created in the late 1960s. Sanchez didn’t quite agree with the angled stud and bolt arrangement or the lack of water ports in the center cylinders. That was something he’d never seen before. But Sanchez feels the Stag heads are well designed in many areas.

I explained to Sanchez that most Stag heads warp because of overheating caused by low coolant, an ineffective radiator or other problems. Once a Stag engine overheats, marginal cylinder head sealing becomes totally ineffective and causes coolant leaks and uneven compression due to warping. Total Flow can fix most warped heads by a combination of welding in new metal in low areas and resurfacing the gasket faces. But, Sanchez warns, if the head is so badly warped that the camshaft doesn’t turn freely, things can get ugly (read: expensive) quickly.

Sanchez believes the Stag’s heads have room for cooling improvements and can be made to deliver higher performance. He thinks water ports could be added to the heads to improve flow. If you look at the Stag engine block, you’ll see each cylinder bore has matching water jackets, but the heads don’t. In fact, in the center of each head, there are no water jackets. The head gasket covers up the jackets on the block. ‘If we have an opportunity to work on more Stag heads, I wouldn’t mind looking into that. I’d like to drill some holes and see if we can transfer some water.”

For a 3.0-litre overhead-cam V8 engine, the Stag doesn’t make much power by today’s standards. But Sanchez also sees ways he can increase the amount of air and exhaust that flows through the heads. ‘Everything starts at the valve seats, the seat angle where the valve hits the seat,” he says. ‘That’s where everything happens right there. I always approach any kind of engine build that you start with the exhaust seat.

You have to figure out where the exhaust valve is going to have to go. And build the whole engine around that. Then you try to put the intake in the happiest place in the chamber.”For me, any kind of performance improvements will have to wait for my next Stag engine project. Sanchez’s refurbished Stag heads are about to be installed on a freshly built block with balanced 0.40 pistons, rods and crank. I am expecting a smooth, quiet engine that runs cool. The Stag engine can be a very sweet engine, I have learned. And now the last thing I am going to worry about are the heads.Looking back, I know I made the right decision in trusting Total Flow to fix my Stag’s heads.

You want a guy like Sanchez doing that kind of work. He likes the challenge of fixing something that most people would throw away. ‘That was a more difficult repair than an explosion,” says Sanchez. ‘In an explosion, unless the floor of the valve seat register is just completely wiped out, you’ve got good metal to adhere to. Most shops would have never touched that job.”

If you’ve got Stag heads that need work, Total Flow will examine them free of charge. You, of course, have to pay the shipping both ways. But Sanchez will tell you if your heads can be saved. Mine were about as bad as they get, so with what Total Flow now knows about Stag heads from rebuilding mine, yours can probably be fixed, too. And another Stag can live with its original engine.

Need to know:

Total Flow Products
1197 Rochester Road, Suite N
Troy Michigan USA
Telephone: +1 (248) 588-4490

Keith Adams
Latest posts by Keith Adams (see all)

1 Comment

  1. Great article. Just about to rebuild my stag engine and I just know that there will be problems. This place sounds just what I am looking for.
    Thanks very much

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