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Spitfire 1500 Coil


Fergusminto

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My 1500 Dolomite engined Spitfire is almost impossible to start in winter. It has Sparkrite electronic ignition. Timing was at 14 now at 10. Carbs properly balanced. Could prob be the coil. The car has a ballast resistor and the present coil is a Lucas DLB105 which apparently is high performance but NOT recommended for a ballast system. Could this be the cause?

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Think you have two possibilities, one bad and one even worse. The first is the system is working as it should so you start with about 12v to the 12v coil but then the ballast cuts in and youre driving around with 6v to a 12v coil. The other is that the system is not working so youre then also trying to start with 6v to a 12v coil!

Fortunately theres two possible solutions. Keep the 12v coil and get rid of the ballast system or buy a ballast rated coil and check to make sure the system is working correctlyūüĎć

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yes  you need to check just how your coil is wired up

do you have a simple multimeter ??

DLB105  is a 3 ohm non balasted coil    needs a full 12v feed all the time  no ballast wires .

what wires feed your coil    a balasted feed is a dull white with a pink trace wire  this drops the ign feed to around 6 v    to aid starting  there is a yellow/? 

that links the started solenoid to your coil to give the 6v a 12v boost when cranking these coils are only 1.5ohms 

running a 3 ohm 12v coil with no solenoid link and starting will be difficult , and to add more if you have the remains if a ballast system but no solenoid link you may 

not have any ignition feed when cranking  !!!  

if its been converted to non ballast then the wire colour will be whatever was used  ( white would be correct) and no feed from the solenoid

and a 3 ohm coil to be used 

as said running a 12v 3 ohm coil on 6v gives a very weak spark around half the require HT

 reverse that idea and give  a 6v 1.5 ohm coil a full 12v feed and you double the HT and double the current to the point/lecy unit  this blows rotors and caps.

Pete

 

 

 

 

 

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There should be a second wire connecting somewhere on the coil side of the resistor that on start up supplies 12v to the coil instead of the 6v from the ballast. If the former got lost in the engine change it would explain the poor starting although of course just because its present doesnt mean its working! Anyway you can just connect the 2 or 3 wires together to do away with the ballast...

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There are two wires at one end of the BR and one at the other. I will play about with it tomorrow! It would be a joy to have it starting without running the battery down in winter - and presumably the spark in each cylinder will also be stronger when she is going! One can hope!

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That’s the ignition taken care of now. Ballast Resistor bypassed. Can’t say the started any better but at least she started! I suppose, now, I will have to retune the engine - mixture, carb balance and timing. Can anyone advise on the definitive static/strobe timing on a 1977 1.5 Dolomite engine. I was, at one point, advised 14btdc but due to starting probs I took it back to 10. 

Thanks to all btw - I seem have been running that engine with a 12v coil and a 6v supply.

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16 minutes ago, Fergusminto said:

That’s the ignition taken care of now. Ballast Resistor bypassed. Can’t say the started any better but at least she started! I suppose, now, I will have to retune the engine - mixture, carb balance and timing. Can anyone advise on the definitive static/strobe timing on a 1977 1.5 Dolomite engine. I was, at one point, advised 14btdc but due to starting probs I took it back to 10. 

Thanks to all btw - I seem have been running that engine with a 12v coil and a 6v supply.

The engine in my 1500 has a DM number so presume from Dolomite, but I believe it is supposed to be the same. I am currently running at 14deg BTDC and it starts on the button in warmer weather but needs a bit more cranking when it's cold out. But last year I was running it at the spec 10deg and it was exactly the same. It does crank slightly slower when cold, presumably due to thicker oil, so maybe that contributes. Or maybe it's the fuel not vaporising as much when it's cold but in my car, the timing doesn't seem to have much effect on this.

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1 hour ago, Fergusminto said:

That’s the ignition taken care of now. Ballast Resistor bypassed. Can’t say the started any better but at least she started! I suppose, now, I will have to retune the engine - mixture, carb balance and timing. Can anyone advise on the definitive static/strobe timing on a 1977 1.5 Dolomite engine. I was, at one point, advised 14btdc but due to starting probs I took it back to 10. 

I havent heard of timing affecting starting so much as giving pinking (rattling sound in engine on acceleration) which is also affected by the fuel octane rating. Most people set their timing to the book and then, if theres pinking with the fuel they want to use, back off the setting until it stops (definition of this is the rattling ceases on reaching 2000rpm when under full acceleration in 4th gear on the flat). Of course everything else has to be correct such as mixture, distributor condition etc...

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2 hours ago, johny said:

I havent heard of timing affecting starting

If it's very advanced it can cause the engine to kick back and refuse to start. My Spitfire used to do that when the mechanical advance stuck on. It sounds like a flat battery / very slow crank. I wouldn't expect 14 degrees to be that bad but it will change the response somewhat.

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Hi Pete

Answers!

Replaced the waxstats three/four years ago.

Starter fine - battery, of course, runs down often but it is a heavy duty one and only a year old.

Choke operation is a possible problem. Jets are sticky so I silicon them from time to time. Adjustment of choke I must read up on.

no running problems but can run-on when switching off. This could be attributed to running a weak 6v spark from a 12v coil?

what is the significance of R rated plugs? I will check. The ones I have are basic Rimmer/Moss supplies.

B

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2 hours ago, Fergusminto said:

Choke operation is a possible problem

Choke operation could be a beneficial line of investigation. Badly set up enrichment can greatly hamper cold-starting. But it's a matter that's rather skimped over in both Haynes and the Ops. Manual.

With HS4s (for example) it's possible to have a situation where the choke linkages have an unequal action on lowering the jets - thus impairing enrichment. 'Equal' is not a precise measurement, visual inspection will do. Similarly the action of the choke linkage on the butterflies may be unequal, premature/excessive, or both: Too much extra air, determined mostly by the fast idle screws, can nullify the effect of extra fuel from lowering the jets.

The choke cable, and it's attachment at it's trunion on the rear carb,  itself can warrant examination/correction : Such that the cable overall itself is neither too tight nor too slack and gives a smooth, full, range of movement. 

Well worth a look.

 

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