Triumph TR7
After a year and a half, the TR7 is back on the road
Give me an A-series and I will happily spend a day rebuilding the top end and putting it all back together. But the Triumph slantfour is a slightly less straightforward beast. It was easy to start with… I’d removed the head and had it machined after major failure of the head gasket in summer 2019 and I had removed and rebuilt the water pump, too. I was a Triumph hero in my own head. I had then started and almost completed the process of fitting a new timing chain and tensioners. That’s when I had a wobble. I was ‘almost’ certain I had done it correctly, but I wasn’t ‘entirely’ certain. It looked right and I had followed the correct process, but I needed reassurance.
Robsport International near Royston in Hertfordshire is pretty much ground zero for TR7 and Stag expertise. It is also only down the road from where I live, so I threw the wedge on a trailer and dragged it down there. Time to learn Triumph slant-four properly.
Boss Simon Hebditch, (his dad ‘Rob’ started the business), greeted me with a knowing smile and guided me to a service bay. I was to have the best of both worlds: get to sort my car and have expert instruction. Ben Porter was to be my Yoda and first – ‘told me set up a tidy workstation, he did.’
I cleaned the head thoroughly and then sealed the inlet manifold gasket to it with Sikaflex, the engine was given the same treatment and the distributor was removed with HT leads marked. I set the jackshaft pulley to the correct position (there’s a scored line that needs to be angled at just gone a quarter past three). Then I dropped the rebuilt water pump in having removed the old bearing cage and replaced it. Gentle tapping with a rubber mallet saw it home.
Most important here is to check the pump’s securing nut is not touching the water pump cover. A dob of grease on the inside of the cover followed by a fit and an ‘assess’ showed I needed
a slightly thicker gasket to avoid the possibility. This mechanical water pump design is ingenious, but also ridiculously over complicated. A front mounted pump would have been simpler, less prone to leaks and failures and easier to replace. The lack of room at the front end of the engine on the Stag V8 (the slant-four is basically half a Stag V8) is apparently the reason for the positioning of the water pump in the engine block.
On with his head
With all this completed it was time to fit the head. The notorious angled studs were first in followed by the gasket and then the head, all surfaces sealed with Wellseal, old school but effective. The bolts were then inserted and nuts fitted to the studs. Everything was torqued up to 60lb ft… not 55lb ft as it says in the workshop manual. The ‘55’ guidance was corrected by BL with a supplement in the late Seventies, but this piece of paper was soon lost. Most original manuals still state the 55 figure – it is wrong and you risk further gasket failure by sticking to it. I retorqued it to 60lb ft three times at 20 minute intervals.
In between straining at the wrench I, under the watchful eye of Ben, made sure the engine was at top dead centre and the camshaft was correctly orientated. Then we started setting up timing chain. Chain over pulleys first with guides in next and then the tensioner. I reapplied the top pulley to the cam and fitted the lock tabs to the pulley.
Then it was out with the sealant and on with the covers – time consuming and dreary, but worth doing carefully, particularly where it attaches to the sump – a slapdash approach would result in a fantastic oil leak. Alternator and crankshaft
main pulley were next, followed by the cam cover… and then it was time to go home. Working with Ben had been immensely helpful.
Dawn breaks, TR7 doesn’t
A new day and I got straight into things – unpacking a fresh bag of hoses from Rimmers and some ethanol compatible fuel lines. As I removed the old fuel lines they disintegrated, crumbled and split in my hands as I took them off. They looked OK in situ. It was only when manipulated that they revealed their secret. Go to your classic now, squeeze and bend your rubber fuel lines and see what happens.
Next on was the thermostat housing with its direct fitting into the water pump, a smear of silicone sealant helps avoid leaks here. Then it was on with the carbs at last and the fan, belts, radiator and coolant hoses. New points, new plugs, leads, cap and rotor arm were all fitted fresh from the Robsport ‘cave of new bits’.
Suddenly it was time to fill the engine with its required juices. All timing marks were checked and the engine turned over to get pressure. Then I fired it up. And it ran! The cooling system needed a couple of ‘burps’ but soon settled and everything appeared normal. One new headlight and track rod end later, I had a ticket.
Another oil change was required to get rid of the last of the emulsified gasket fail gloop and then, the last major job for now, fitting a recon rear axle. I had one, and if this car is to become daily transport in 2021 then, with the Polybushes I fitted earlier in the year, I’ll be thankful for it.
Job done. I now have a TR7 that has had enough attention to last it for several years. Thanks to Robsport and especially Ben, I have full faith in the car’s ability to go anywhere. Must remember to re-torque the head after 300 miles though.
‘This TR7 has had enough attention to last it for several years’