Wrong coil on Spitfire Mk 3?

[Mark D]

Hi all, 

First time on here and pretty much a complete novice with cars! Bought a 1970 Triumph Spitfire Mk iii 1300 a few months ago - partly because I've always loved them, and also because I wanted to start learning about classic cars - just didn't think the learning curve would happen so quickly haha

Anyhoo - if anyone could please advise me on something I'd be hugely grateful! I'm sitting here with a big pointy hat with the letter 'D' on it when it comes to mechanics, so please excuse me if this situation seems completely daft! 

The original coil she came with was overheating and I couldn't restart her until it'd cooled right down. 

Couldn't figure out if she was supposed to have a ballasted or non-ballasted coil, so somewhat irresponsibly bought two - a Lucas DLB105 unballasted (gold), and a Lucas DLB110 (ballasted). 

So the irresponsible bit was I took a gamble and installed the unballasted one. I'd had problems starting her up previously  - often like 10 attempts. When I put in the new  coil she started up absolutely beautifully! Chuffed with myself that I'd solved the issue I took her out for a spin - probably about 15 miles or so. 

Suddenly it felt like the engine was dragging - she wouldn't really accelerate - I dropped her down into 3rd from 4th and it seemed to correct itself. However about 5 minutes later I lost all power. The coil was warm but not roasting hot like the old one. I tried swapping the coils over, installing the ballasted one, but no joy - she wasn't even interested in trying to kick in - so a friendly neighbour towed me home. 

2 days later I go out and give her a go turning over - started up beautifully - no problems at all. Didn't drive her though. 

This was three weeks ago. Went out yesterday and the battery had drained (previous owner had put in an immobiliser system which the local garage said I should remove - not sure if that accelerated the battery draining - I guess so?) 

Charged up the battery (2 month old one) - put the other new ballasted coil in and again, she started up beautifully. 

However, now I don't feel particularly confident to take her out for a drive in case the same thing happens and she cuts out 

So, I guess my questions are: 

Did I install the wrong coil originally? 

If so, could the effect have been the complete loss of power that I experienced, and with the new ballasted coil in, do you think the problem might be resolved? 

I understand that over a long period of time, having the wrong coil in could compromise the points (?) - I'm wondering if it too much power was going through the electrics and it cut out? 

Apologies for the long post - any advice would be gratefully received - all this gorgeous autumnal weather and I can't go out and play! 

As much as it's frustrating though - loving the learning curves

Many thanks 

Mark 

 

 

 

 

 

[Pete Lewis]

this is an old nutshell ,

the basics   

there are two ballast ideas one is a ceramic resistor fitted near the coil  the other is a dull pink white wire built into the harness.

this drops the coil voltage to around 6-8volts  there will be a second feed to the coil +ve terminal from the starter solenoid so when you crank you boost a 12v  to the coil +ve (  the -ve terminal feeds the points )   make sure they are the right way round , the dizzy leead is same as the battery earth polarity

checking coils.... a12v measures 3 ohms across the blade terminals  a ballast coil is 1.5 ohms 

one point if checking the feed with a meter the points must be closed or you will read always  at 12v 

 

if you run a 1.5 ohm coil on a full 12v fed you double the HT and double the current at the points overheat the coil and blow rotor arms

especially ones with a rivet in the sweep plate ( delco rotors are less trouble)

make sure the centre brush in the dizzy cap actually contacts the rotor

if you cant use a meter to check your ign coil feed voltage look for the ceramic or the dull white pink feed these must have a ballasted 1.5 oh coil

 

some 1.5ohm coils are marked as 12v being the base car voltage just to confuse things more

my guess is the coil ballast  has been  bypassed and you had a ballast coil running in 12v and have cooked the points condenser and rotor

its a common problem of mix and...... not match 

Pete

[Pete Lewis]

one thing that can happen to a over heated coil is if the bobin is wound tight then the heat expansion can break the connecting wires to the blades , it cools and things seem to return but not for long. 

just an out the box thought 

Pete

[dougbgt6]

Just to clarify, Pete is correct (as usual) but I would describe the ballast wire as grubby white with a barely detectable dull pink fleck. If you have one, one end can be found on the ignition switch, the other end can go to the starter solenoid or the coil. The wire is resistive and does the same job as the ceramic resistor, so it's one or the other, or nothing at all!

[Mark D]

Thanks for taking the time to reply Pete and Doug - most appreciated! 

Definitely have the ceramic part as the coil bolts down on top of it. I think I'm nearly there - going to check over the pointers you've mentioned Pete (poss get a mechanic mate to double check!) and then hopefully I'll be able to take her out again

Thanks again guys - really appreciate it

 

[dougbgt6]

Mark, a cheap multimeter is an excellent addition to the tool kit, you can get 'em for under £5. And it will, in this case, tell you all. 

[Pete Lewis]

just to add there are some real nasty  near empty condensers about in the after market.

 

if youve fitted a replacement recently that could be your gremlin

Pete