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Name this dizzy, please


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......still pondering my No 3 cylinder sooty plug......

The issue manifested itself after a few months use since last plug clean so it will take a while for me to find the issue by elimination.

I'm thinking of replacing the NGK plugs in favour of Champion N9Y.

Later, I may change HT leads, cap and rotor arm hence I've attached a few pictures and asking those with knowledge and experience to tell me which dizzy is fitted such that I can source the correct parts?

Many thanks in advance.

 

 

Spit dizzy 3.jpg

Spit dizzy 2.jpg

Spit dizzy 1.jpg

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grab the rotor spindle and does it wag sideways , delco suffer from lack of lube  you should squirt a bit of engine oil down thro the base plate to lube the top spindle bush 

its often a hole in marked  "oil"  

no oil lends to disaster happens a lot  lucas are the same but survive better 

the top bush is not engine lubricated 

if there is side play the points gap will be all over the place as it rotates 

Pete

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Also, check that the rotor arm can rotate a little bit, moderately freely, with a preference for one way. This shows that the mechanical advance mechanism is free to operate - they often get stiff or even rust up solid due to the lack of lubrication that Pete mentioned.

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Thanks, both, very helpful info.

There's no side play on the rotor spindle and it rotates moderately freely anticlockwise, viewed from above.  I last lubricated it as part of its start of season service in April.

My car has done 55,000 miles and was last MoT'd in 1987 prior to completion of its resto a couple of years ago.

Subjectively, the rotor arm fit into the spindle doesn't seem as secure as I'd like it to be but I have no reference.  I may buy an ignition service kit from the club shop as it seems good value.

Since cleaning the plugs, the engine runs well both cold and hot.  In retrospect, it had started to feel a tad rough when on choke, but smooth when at working temperature.  I removed the plugs to adjust the tappets and found a single, sooty plug.  I imagine that it will take a few hundred miles for the issue to manifest itself again.  This time, I'll be more aware of the telltale signs.

Finding the culprit is all part of the joy of ownership.

 

 

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soot from choke can take many many miles to burn clean  if cold starts get over choked and lumpy  increase the fast idle by adjusting the linkage/por cam screw 

on full choke you need around 1500 or more   the first 1/2 of choke should give you a 1000/1200 idle without any enrichment 

ie it  just ups the idle without dropping the jet or operating the starter chokes depends on what carb you have 

Pete

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Thanks, Pete,

I believe that the linkage is set correctly; the first 1/2 or thereabouts increases idle without adjusting the jets.  Carbs are original SU HS2s. 

Incorrectly set, wouldn't explain why only a single cylinder appears sooty, would it?

I've bought a new compression tester but waiting for it to arrive.  My ancient Gunsons, from the 70s, expired when I pressed it into service but before doing so it gave me some confidence that all was well.  I suspect either plugs or the spark distribution system.  Electrickery remains the work of the Devil in my experience so my only option is to change it. 

I don't think it's a big issue, I only found it by accident, as I wanted to check the tappets.

I seem to recall that in 1976, when I last had a Spitfire, I had to adjust the carbs virtually once a month as I had a 300 mile weekly commute.  My Mk3 seems to run at least as well as and probably a bit more stable than my Mk4 at that time. 😃  

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1 hour ago, Mathew said:

So maybe that plug is failing?

Certainly possible. If a plug isn't working well you'll get misfires, and that means potentially residual fuel, so the next burn is rich and the plug soots up. The soot encourages residual fuel retention (especially if the whole engine is a little on the rich side) making it worse.

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