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OK ... on the road to getting the car back on the road and the MOT was booked. 


I drove the car to the test station and clearly all was not well, loads of brake pedal travel, new master cylinder, rear cylinder, front calipers new seals and pistons.


Anyway brakes werent going to be an issue as the car was hugely hesistant then misfiring really badly so abort abort abort....


New condensor fitted a little improvement (the last one wasnt old though). The rich smell of petrol pervaded the air so screw up the jets.  Still back firing.

Now I cheked the timing chain as i fitted a new one a month back all still lining up, TDC on the crank, line on the came matching the cam cap, and the dizzy rotor pointing to the rear inlet manifold so reasonably happy with timing.

Check on Valve clearances.

Inlet should be .008

1 . 0.0028

2. 0.005

3 correct 

4 correct

Exhaust should be 0.018

1 0.020

2 0.016

3 0.020

4 0.020

So i have measured and got new shims on order.


On to checking the Carbs, i rebuilt them but have had issues with float chamber overflowing, new float needles though. The floats are loose on the spindle though so may have ovalled the hole. What level should the floats be?


Compression shows the engine in not bad shape;

1 170

2 150

3 165

4 170


Ignition point coil plugs and leads are all new. 

One point i have wondered about, I set the jet to level with the bridge then turn down 2 turns. However the jet bearing sits a little above the carb bridge, should the two turns be from the jet bearing or carb bridge.

Any one any more ideas on where to check or tips pointers on the above much appreciated.

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Im surprised the jet bearing protrudes above the bridge because the piston could hit it before settling down on the bridge as it should. Normally the bearing sits slightly below however assuming this isnt causing any problem I think the jet adjustment starting point should be flush with the bridge to match the piston/needle position.

Anyway this is just an initial start up setting and will probably need changing on road testing... 

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The mounting pin for the floats is a fairly loose fit. But because the way it is mounted in the float chamber the pin can't escape. As for the float level. With everything fitted to the float bowl lid, hold it upside down and measure the gap between the lid and the lowest  point of the (top of the) float. It should be between 3,2 and 4,8mm.

The two turns should be done at the mixture adjustment nut, the brass nut in the attached picture. Though two full turns might well give a mixture that is too rich.

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Right more investigations;

IT appears I should check before posting the jet bearing IS slightly below the bridge , my memory is going!

I have sorted the valves to within 0.001" so that will do!

Spark plugs have been cleaned, they arent that old either

New condenser in new dizzy cap on

Bob wieghts in the dizzy are free to move and new springs on them too.

The following have been refreshed in the last year whilst the car has been in the garage being welded up

Plugs leads are pretty damn well new. Coil is a new lucas sport points checked and new


I have restarted and still get the occasional miss ...


I have new floats and hinge pins to fit . One of my old hinge pins was well pitted so its getting changed to remove any sticking of the float to incase there is some wear causing it to catch

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Right back out again, got the car running 1500 rpm attached timing light to the car and the timing is quite a lot BTDC adjusted the dizzy but still couldnt get to 10 BTDC. I have checked crank at 0TDC cam cap line up and the dizzy pointing to rear most inlet manifold bolt.

Looking at the top of the dizzy i have the following connections;

Bottom left No1 

Bottom right no 3

Top right 4 

Top left 2.


As I cant get the timing marks to line up, i have a feeling I have made a school boy error with the plug lead connections.

Can anyone post a picture with which lead goes to which cap for peace of mind

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I'd say it's not likely to be the plug leads. Have you had the disi out? Oh, actually, I see you've changed the timing chain. Did you make sure the jack shaft didn't move? It's not sufficient just to time up the camshaft because the disi is slaved off the jack shaft, so if that skips a tooth or three then your timing's going to be out. You can probably fix it by removing the disi and its drive gear then rotating the drive gear a tooth or two, like you would with a Herald that had the disi in the wrong place.

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Robs probably right but before going down that line you could try moving all the leads one place round anticlockwise in the cap and then turn the dizzy back clockwise before checking the timing again. In the end with rotor arm pointing to the inlet manifold bolt the nº1 lead should exit the cap in roughly the same place...

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The Dizzi came out previously, due to a knackered Jackshaft. The dowel on the jack shaft and the centre piece had ovalled out. The locking tab was missing so the gear on the end moved greatly. 

A S/H jackshaft was acquired from Robsport and gear and timing chain. 

With this procedure clearly the Dizzy had to come out , replacement was check TDC insert jackshaft and new gear, Align scribed line, check cam shaft marks. Add timing chain, tensioner check all is correct, rotate engine lots, lines still alligned. Refit water pump fuel pump and then dizzy, rotor arm pointing at rear inlet manifold bolt.

I have No 1 plug lead somewhere near the rear manifold bolt.


Pretty much most ignition components are new. 

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Hopefully some pics will help, been out again swapped leads around one turn around didnt star back to the original position then.

Start car and attach timing light, i have a gunson timing light which allows me to dial in the advance on the back. I set it 20 as the car was running at 2000rpm, manual suggests this is the total advance at 2000 rpm.  I had to turn the dizzy to the extreme to bring the line to 10 BTDC line so still in some advance. 

Whilst running the light missed a pick up and this corresponded with the engine noise stuttering.

Hopefully the video plays i have attached.

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If I remember right the Gunson timing light 'adjuster' is just a means of identifying the engine rpm (in case it has no tacho or its inaccurate) which you turn until the red LED just stays on. The knob now indicates the engine rpm so you can now look up from the manual what the timing should be set at.

If at 2000 rpm you managed to get to 10º BTDC Id say youve got no dizzy problem as it should be around 17º BTDC at those revs. I would advance it to this value and measure it again at tick over revs <1000rpm where there wont be any vacuum or centrifugal advance and you should have 10º BTDC....


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Thanks for the reply, The gunson light is this one https://www.gunson.co.uk/Product/77008/Timing-Light-with-Advance-Feature

the dial on the back allows you to adjust from 0 to 60 degrees advance allowing you just to line the marks up. So effectively I dialled in 20degrees which is what the WSM specifies for 2000rpm which should mean the line aligns at 0 with the crank mark. If i set the dial to 0 it means i should line up the crank with the 10 BTDC at around 1000 rpm with vacuum disconnected. 


If you watch the video you will see the white marks jump as well in a couple of places.

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oh theyve changed the technology since the model I had however I would always set my timing at tickover and then check the advance through the rev range to see how the dizzy is performing.

When you rotated the lead connections in the cap did you rotate the dizzy back clockwise? If not the timing would have been really retarded and might explain why it wouldnt start...

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Yes when i rotated the leads i turned the dizzy back.


I was only at 2000rpm as it had just started on choke and i have to fiddle with the carbs again having adjusted the valves. When fully warm I will go at idle.


I am thinking i need to take the dizzy out and rotate the shaft a gear tooth.

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Right , gear tooth moved one more clockwise so the dizzy arm is pointing more towards inlet tubes now than rear manifold bolt and all is good!

Who knows why mine is like this but considering it was build 5/10/81 I guess it was what left over stuff was left!

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On the small chassis Triumphs apparently theres an issue with the dynamic balancer joint of some front pulleys separating so the outer part with the TDC timing mark can move relative to the crank. This of course then means its impossible to set the ignition timing accurately by the usual method...

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The dynamic balancer issue (which isn't nearly as prevalent as some reports suggest) applies only to the six cylinder cars. The four cylinder SC engine doesn't have one. I'm not sure about the TR7 - there looks to be a raised ring on the pulley which could be the rubber part of a damper?

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Thanks Rob. Looking at the TR7 manual the outer V ring of the front pulley is indeed a separate part from the inner keyed to the crank so gives the possibility of movement between the two.

I suppose the only way of checking TDC is by putting something in through nº1 sparkplug hole to make contact with the piston and indicate when it reaches the highest point?

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