Timing Chain Interval on TR7 1980/81

[Sparkyhx]

Hi,

I'm new and one of the things i've been trying to find out for planning preventative maintenance - what is the timing chain replacement interval.  I'm getting very mixed messages when I search from anything from 25k to 80k,  Any Advice?  My car is new to me (present from wife) and I haven't even seen it yet to see if there are any stickers or anything saying its been done and when.  Every car I've have personally had it done on,  the mechanic has done this.

Otherwise I'm probably going to have to just get it done to be on the safe side.  The car has done 87k so probably best to err on the safe side.  Does anyone know the workshop time duration is?

[Pete Lewis]

its a morse chain  they last for ever but as the pivots and links wear the chain effectively grows in length and the cam timing starts to get a little later than when new   none are jaw dopping events if its noisy have it changed if its quiet sleep easy

there will be a good few thoughts on this but im sure there will be other far more needed repairs to do before you jump into

the bigger jobs   sorry its not something you can pre judge  , use the ears  is a good start

but it wont fail and cause any  catastrophe.

you really need to get to know the car before you drum up worries and empty the wallet 

pete

[Wagger]

I am not sure if your engine is 'Non Interference' if the chain fails. I had an 1850 Dolly which did 180k with no chain change. Usually, you will hear clatter long before failure.

PeteL beat me to this, so looks like the engine is 'Non Interference'.

Engines with Timing belts have made you, and others, paraniod about cam chains. Belts do fail if too old or over used and many engines suffer bent valves, cracked pistons and far worse. I prefer chain driven camshafts. With regular oil changes, they go on for years and high miles.

Edited November 8, 2023 by Wagger

[Nigel Clark]

As has been said, the timing chains on the OHC Triumph engines last well, and will start to rattle when either chain or tensioner is worn and needs replacement.

Make sure you get a good quality chain, New Old Stock if available. There are German timing chains available for Stag engines and they have a good reputation. Don't know if similar are available for the TR7. Cheap eastern chains should be avoided. A TR7 specialist like Robsport or S&S should stock a decent chain.

Nigel

[Pete Lewis]

from experience of warranty  more belts fail after the OE is replaced due to not conforming to the tension tooling etc 

then blame the belt for failing , its rarely the belt that gives out they are made from pretty bullet proof Kevlar 

we had many dealers claim a belt failure a few hundred miles after fitting , when asked where is you tension tool ..."we dont have one " 

bye bye warranty !! 

Pete

[Wagger]

The belts that I have replaced have been on Ducatos, Audis and BMWs. Always replaced the tensioners and Idlers. The procedure stated that the tensioner should be allowed to take up the slack with the spring supplied, then the nut was tightened. It stated that belts should never be re-tensioned in the procedure.

A friend of mine had an early Vauxhall Cavalier FWD. A stone went through the grille and the plastic cam box, went between cam drivewheel and belt changing the cam timing by two teeth. Needless to say, it did not run very well.

Many serpentine belts have spring loaded tensioning pulleys that cannot be locked. They maintain tension and negate the effect of eccentric pulleys.

[johny]

3 hours ago, Sparkyhx said:

Hi,

I'm new and one of the things i've been trying to find out for planning preventative maintenance - what is the timing chain replacement interval.  I'm getting very mixed messages when I search from anything from 25k to 80k,  Any Advice?  My car is new to me (present from wife) and I haven't even seen it yet to see if there are any stickers or anything saying its been done and when.  Every car I've have personally had it done on,  the mechanic has done this.

Otherwise I'm probably going to have to just get it done to be on the safe side.  The car has done 87k so probably best to err on the safe side.  Does anyone know the workshop time duration is?

Yes normally measure the chain to see if its stretched more than the allowable limit when doing other major overhaul work on the engine rather than use mileage. The hydraulic rubber faced tensioner used on these engines is probably going to need replacing before the chain.

The Triumph workshop manual for TR7 is available free to download online....

[Sparkyhx]

On 08/11/2023 at 10:14, Wagger said:

I am not sure if your engine is 'Non Interference' if the chain fails. I had an 1850 Dolly which did 180k with no chain change. Usually, you will hear clatter long before failure.

PeteL beat me to this, so looks like the engine is 'Non Interference'.

Engines with Timing belts have made you, and others, paraniod about cam chains. Belts do fail if too old or over used and many engines suffer bent valves, cracked pistons and far worse. I prefer chain driven camshafts. With regular oil changes, they go on for years and high miles.

I had a Nissan 200sx for 10 years as a toy, The SR20DET was chain driven that was 'life of the car'.  It was a common joke that it meant "if the chain went, that was the end of the car" cos it was an interference engine.  Most people were pushing the specs of the standard engine (270hp from std 200) with no issues, but those pushing beyond the stage 1 build into the 300 - 400hp some people went to the trouble of changing them.  Beyond 400 you were usually looking at changes to the internals anyway, so it would be done as part of that.  Curiously, the related but none turbo'd SR20 was prone to chain issues.

Also same club SXOC had a friend who swapped a Stage 1 SR20DET into a Dolly Sprint - that was a hoot.   

SR20DET powered TR7 anyone?  OMG - Someones actually done it   https://illmotion.com/im-feature-chriss-triumph-tr7/

Edited November 13, 2023 by Sparkyhx