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Author Topic: Crackle and Pop - thankfully not Snap,  (Read 465 times)
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Paul Johnson
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Posts: 17


« on: 13 July, 2020, 08:23:00 PM »

Enjoyed a run out this afternoon and the misfire on my S2 never seems to go away. It definitely lessens as she warms up, but should I be worried? Always when coasting - letting off the throttle, but also under gentle acceleration.
New plugs fitted very recently.
Thoughts appreciated.
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1972 Fulvia S2
nistri
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Posts: 313


« Reply #1 on: 14 July, 2020, 01:39:14 PM »

Did you check the ignition timing? Andrea
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Andrea Nistri

Ardea S2
Appia S2
Fulvia GTE
Fulvia Sport 1.3 S
Fulvia Montecarlo
Fulvia Coupe 1.3 S
Paul Johnson
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Posts: 17


« Reply #2 on: 14 July, 2020, 07:24:18 PM »

Nope. Probably beyond me, but willing to learn.
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1972 Fulvia S2
SanRemo78
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« Reply #3 on: 14 July, 2020, 08:20:23 PM »

Do Fulvia distributors have bob weights to advance the timing? Possibly seized or weak springs?
Guy
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Mikenoangelo
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Posts: 174


« Reply #4 on: 14 July, 2020, 08:27:30 PM »

If the distributor has a vacuum advance I'd suspect that. On light throttle or on the over-run the vaccuum advance mechanism should advance the ignition (this is when the vaccuum in the manifold is at its greatest). If it does not then under those conditions the ignition is too far retarded to properly fire the restricted amount of air/fuel mix some of which escapes into the exhaust and pops and bangs resulting in the symptoms you describe. Make sure the pipe connecting the vaccuum advance to the inlet manifold is sound. If it is then possibly the vaccuum actuator on the distributor is faulty. I've not tried this but if you had an ignition strobe light to watch how the spark related to the timing marks on the flywheel or the fan pulley, youa could try nipping the rubber vaccuum pipe to see whether the timing changes.

Mike
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nistri
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« Reply #5 on: 15 July, 2020, 07:16:08 AM »

The distributor does have bobweights (that rarely go wrong). I suggest to read the Fulvia manual for checking the ignition timing: this is often out and also changed by the points wear. Andrea
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Andrea Nistri

Ardea S2
Appia S2
Fulvia GTE
Fulvia Sport 1.3 S
Fulvia Montecarlo
Fulvia Coupe 1.3 S
lancialulu
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« Reply #6 on: 15 July, 2020, 07:35:07 AM »

If the distributor has a vacuum advance I'd suspect that. On light throttle or on the over-run the vaccuum advance mechanism should advance the ignition (this is when the vaccuum in the
Fulvia Distributors do not have vacuum advance.

After checking the timing you might have some issue with blocked idle jet especially if the car has been standing for a long period of years before being used. The pilot jets are accessible under the small cover on top of each carburettor. They are the shorter of the jets (2 per carb).
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Its not the winning but taking part! or is it taking apart?
1955 Aurelia B12
1967 Flavia Vignale iniezione
1967 Fulvia 1.3HFR
1972 Fulvia 1600HF
1972 Fulvia 1600HF
1972 1600 Fulvia Sport
1979 2500 Gamma Coupe
1988 Delta 1.6GTi
1998 Zeta
davidwheeler
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« Reply #7 on: 18 July, 2020, 08:52:16 PM »

You will find elsewhere reference to the "idler"/"slow running" jets and advice to increase the size to cope with the higher viscosity of modern petrols.   For instance http://www.lancia.myzen.co.uk/forum/index.php?topic=10197.0 
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David Wheeler.  Lambdas, Aprilia, Fulvia Sport.(formerly Appia and Thema as well).
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