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Triumph Repair/Triumph TR7 Timing Chain Replacement

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QUESTION: Hi Howard:

I have a general question about TR7 timing chains.  Do these units require periodic replacement?  If so, at what intervals and what symptoms indicate it needs replacement?

The reason why I ask is that I know the engines on the TR7 and Stag are related, and that the stag does require timing chain replacement at 24K mile intervals (if memory serves).

Thanks for your help,
Matt

ANSWER: Hi Matt,

I was factory trained on the TR-7 engine and I never seen any recommended chain replacement time. The tensioner is an oil pressure operated automatic adjuster.

If however the head has been off and resurfaced or the top of the block surfaced "decked" it is advisable to check the travel of the automatic tensioner to see that it is not extended too far and running out of travel.

Excess chain ware can be checked with the cam cover off and grab the chain at the very top and pull up to see if there is any slack in the links at the very top of the sprocket. A badly worn chain can still be tight but the links at the very top of the cam sprocket will be loose. This is an indication the chain needs to be replaced. It is also normal procedure to replace the chain when any engine rebuild is done. Even just a ring and valve job.

The TR-7 was half of the Stag V-8. The TR-7 was designed to be an MG and to replace the MGB and receive the Rover 215 V-8 (Buick / Olds engine) but the engine was not ready when the car was finished and BLM decided to take half of the Triumph Stag and make the car a Triumph. When the Rover 215 was ready they put it in the car and called it the TR-8 Triumph.

The TR-7 got a bad reputation because of the odd design and mechanics who didn't know how to work on them. It was necessary to know how to replace the water pump in the block and how to work on the head due to the odd design angled head studs.

Any time that the engine overheated the head would warp and no American auto machine shop could straighten the head before surfacing and that made the cam bore out of alignment causing the cam to break. And even if they did get the cam bore straightened out (most machine shops didn't have a boring bar small enough to do the head) And if they did it left the valves too long and no valve adjustment could be done unless the valve stems were cut short. This also made the Triumph valve shims not have enough range to get the valve clearance. Some mechanics figured out that the SAAB 99 valve shims had a wider range and could be used. Additional problems with the Opus / Lucas electronic ignition system that failed often and all of that gave the TR-7 a bad name. The car also had a headlight system that was troublesome and the early models had wheel bearing problems. However, in the later TR-7's most of the car had been corrected except the head. I owned several and learned to like the car.

Howard

---------- FOLLOW-UP ----------

QUESTION: Hi Howard:

Thanks for the information.  I will check the timing chain very soon.

One further question, which is unrelated to the TR7 timing chain.  

I saw something on a TR7 related internet site that the viscous coupling on the fan can seize, causing the fan to go through the radiator.  This site indicated that lubrication was required.  I cannot find anything in the TR7 ROM about lubricating this part.  Can you comment/advise on this?

Thanks for all your help,
Matt

Answer
I have had some fail but most don't have any way to lube them. Different brands are designed differently. Some have a small screw to remove and fill them. I found one that could be taken apart. If you have one with the refill screw the oil is Silicone Oil. Usual test is to feel for any play in the bearings and if there is any free play (Wobble movement)you need to put on a new unit. Also rotate the blade to see if you feel hydraulic resistance, if not replace it or fill it.

Howard

Triumph Repair

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Howard M. Fitzcharles III

Expertise

Triumph TR-4 up & Spitfire, and Engine theory

Experience

Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

Organizations
Associate member SAE EAA member

Publications
Import Car magazine

Education/Credentials
ASE Master Auto with L-1 certification up to 2000

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