The Triumph Dolomite Club - Discussion Forum

Hello all

I’m my quest to trace the noise I’m experiencing in the engine bay. I’ve been going around with the long screwdriver and ear trick and believe I’ve traced the noise to the dizzy.

The noise is like a loud clockwork toy at high speed! I guess the dizzy is shot? But what could cause the noise? Mechanical advance weights? Has anyone else experienced this? It’s not the rotor and cap - the noise comes from the body of the dizzy.

I’m guessing that a rebuild is necessary? Distributor doctor or elsewhere?

All help appreciated.

Bish.

Hi Bish, not got a broken bob weight spring have you?

Tony.

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NOW A CLUB MEMBER 2017057

I guess I’ve got to whip the dizzy out and have a look Tony. I’ve never had a dizzy apart so it will be interesting to have a look at it. When you say bob weight spring - that’s the mechanical advance?

I was wondering if anyone has experienced a noisy dizzy themselves? When trying to trace the noise in the engine bay I wasn’t expecting it to be coming from the dizzy! I had suspected tappets and or timing chain.

That's the little devil's Bish, there should be two from memory.... I have only seen 3 or 4 break in my time, but all in lucas distributors. They are not difficult to take apart just fiddly, use a magnetic screwdriver when undoing the baseplate screws unless you are taking the dist out. The weights could possibly be hitting the side of the casing if a spring has gone. It will be obvious when apart

Tony.

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NOW A CLUB MEMBER 2017057

Take the distributor out - I'm assuming we are talking a Sprint, not a 1300/1500.

I know the set screws that hold it down are little buggers to get at - even worse in the TR7 Sprint -, but doing the springs in situ will be awful. I don't even like doing the points in situ.

Also, I have on occasion, forgotten to turn the engine to a known position before pulling the disy - TDC No 1 cylinder, with the rotor arm pointing at the lug that locates the cap is my pref. Last time I forgot, I got the wrong TDC putting it back first time - thought I had it at top of compression on 1, but didn't. That heart rending moment when it won't fire!

Graham

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The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

Thanks chaps. It is a sprint, and yes it’s not the easiest dizzy to access, so I’ll take the it out to get a proper look at it. I may send it for reconditioning dependant on what I find. I know there’s a little play in the shaft so it may be time to get it sorted. I’m thinking the distributor doctor is the man to go to. Or, has anyone had any experience of ignition car parts in Essex?

Well, the dirty dizzy is off and on the bench.



It appears that the springs have seen better days as Tony suggested. They aren’t snapped but are very loose and the weight mechanism is slopping around. When I spin the shaft the weights are clacking more like a maraca than a dizzy! In the last photo you can see how loose the bottom spring is, it’s not holding on to the pin.





I hope that’s the noise that I’ve been trying to trace, found at last?! And to think that I thought the car accelerated well, but it can’t have been quite right.

I guess I could find springs and fit them but I reckon it’s time for the distributor doctor. He’s quoted £195 + the dreaded vat for a full recon. If his service is as good as his reputation then it should be money well spent.

I've taken a few apart that had one spring loose and weren't noisy - it may even be all of them were like that. And I'm not sure how those springs, given their size and the relatively small extension asked of them, would ever be strained to the point of yielding in use.

Graham

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The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

Fair point Graham. I’m convinced that’s my noise though. Surely those springs must need to be taught? Just spinning the shaft, by hand back and forth, has the weights slopping about noisily.
I’ve booked it in for a refurb. Piece of mind and all that. The four week turnaround is a bit strong though. I hope I get it back soon enough for a few drives before the weather turns to crap.

One of those springs was doing nothing Bish, so it should run better with it done Did you see the one on fleabay? £165 looked almost new, and not exchange.

Tony.

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NOW A CLUB MEMBER 2017057

Yes I did see that one Tony, but I thought with it’s condition being unknown it was a £165 punt. Punt as in gamble! If I had a spare £165 I would snap it up as a spare. When I weighed up my options, I thought my funds were best placed with a recon from a guy with an excellent reputation.

Like you say the car will certainly run a lot better with the recon dizzy so it will be money well spent. Whether it solves the noise mystery? We shall see.....

It don't mean it's doing nothing if it's slack at zero rpm, it just makes for a corner in the curve between rpm and advance.

That is, it lets advance increase quickly with increasing rpm, set by the other spring, which, from what I've seen is the lighter of the two.
Then advance increases more slowly with increasing rpm, once it goes beyond the advance/rpm value at which the gap between the spring and pin closes.

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

Can I ask which points you use Bish? I'm hearing so much about poor quality Lucas parts now, that maybe getting a stock of old stock may be the way to go.

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Triumph Dolomite Sprint,RNK 957W

Built 26/6/1980 (one of the last built), Auto, Porcelain White - Genuine Mileage 52,820 (warranted).

Only 3 previous owners, (2 within the same family).

Supplied by Lavender Hill Garage Ltd, Enfield, London, by garage owner Jimmy Metcalfe on 30th September 1980 to Geoffery Robinson, Enfield.

Club Membership No: 2017092

An average pic of an advance curve. The light spring causes the first steep part from idle. When the second spring start helping the advance is less related to rpm as two springs are holding the weights from now.

There need to be two different springs and you cannot mix up or use springs from another dizzy. These may look the same but probably aren't.

Jeroen

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Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com

And in order for there to be a kink in the curve, one of the springs has to have no effect, i.e. be loose, below the rpm where the kink is.
The second kink is where the bobweight hits the stop, the advance angle of that being stamped on the weight in degrees.

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).