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Help misfire


hardyferret

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so the ferret runs but i have the following not as sweet as it should be,and if i rev up it backfires on the over run through exhaust not the carb

so far i have put in new points and condenser, plugs cleaned and gapped and fresh fuel

So any ideas from you all gratefully received

Regards Jerry

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so the ferret runs but i have the following not as sweet as it should be,and if i rev up it backfires on the over run through exhaust not the carb

so far i have put in new points and condenser, plugs cleaned and gapped and fresh fuel

So any ideas from you all gratefully received

Regards Jerry

 

 

Jerry,

 

You headed this thread "misfire", is it actually misfiring or only banging on the over run? I have to ask, have you had this Ferret running before? So many questions, but this is my job you see :-)

 

On Ferret exhausts the two tubes which link the manifold elbow to the hull elbow, are intentionally slack, because the engine has slight movement in its mountings. After a time the tubes rattle in the elbows and also scale them selves, resulting in a looser fit. Now on over run, any leak in the exhaust system is going to result in backfires.

 

What you have to determine, is whether the performance is down or whether it is just banging on over run, due to leak in exhaust system.

 

Richard

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Did you synchronise the points as per the manual? Was the condensor a new one or one which has been in a box for years? Also check the mixture screws, remember there are 2 of them and you must do exactly the same thing to both of them.

 

Have you left it to warm up? Does it do the same thing when warm? Those tubes Richard talks about should expand and close up any gaps when warm.

 

Chris

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Sorry Richard

 

Has run before but has and did have tendency to hunt at tickover ie revs not steady

 

 

Jerry,

 

OK, something to work on now. Assume you have done everything correctly. Now this bang on over run may not be due to a leak in exhaust, but weak mixture on idle settings. Might pay to richen the two needles, not forgetting to move them equally as per the EMER.

 

Richard

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Thahk you richard will try also I will check timing and syncro what voltage bulb for tester??

I have another carb which looks brand new may go the whole hog

 

All this started due to hunting as described no bang so cleaned plugs and gapped

had a nos dizzy so used points and condenser

at this point it all goes tit shaped.....

why can we never just leave things alone..........

 

feeeling silly Jerry

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Jerry

 

before swapping the carb, the other standard check is to ensure you get two equal measure and pressure jets of fuel when you operate the accelerator pedal since unequal fuel supply would manifest on overrun and might sound as a misfire

 

- take off the airhorn from the carb

- operate the accel linkage and look down the carb to see the petrol squirts from the 2 tubes

- if they are unequal you may have a worn or failing diaphragm (or just dirt blockage) in whichever side of the carb is poor, replacing these diaphragms is easy but no point listing that here if the jets are OK

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Thahk you richard will try also I will check timing and syncro what voltage bulb for tester??

 

 

Sorry Jerry,

 

I missed this message last night.............you can only test the syncro of the two sets of points (or as I call it, phasing), with the distributor removed from the engine, you also require the test jig as shown in the EMER. A battery and test lamp can be used, obviously bulb same voltage as battery, easy as that!

 

It may be better for you to back track to see what you have done to cause this to happen. Best of luck.

 

Richard

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