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** ON TO THE NEXT BIT ** Nose to Tail - 1972 Spitfire MkIV restoration upgrades!!


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1mm will take approximately 17A - so good for most circuits - though you need to consider volt drop.

2mm will take approximately 25A

If it were me, I would use mostly 1mm and then 2mm for higher loads. Possibly 3mm on the headlights to give the lumens a chance to shine ;) 

Stick a few 2mm cables in a harness and it will soon bulk out!

 

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It's bizarre that the factory used thin earth wires. I think it was because, traditionally, the earth wires were short and ran to a body fixing, then relied on the substantial chassis to provide a good earth return path. In reality the earth wire carries as much current as the feed; more in the case of headlights because there are two feeds and only one earth (although you don't normally have both feeds on at once, except when flashing).

Like Mark, I would stick with 1mm cable for most circuits (incl. sidelights) and 2mm for heavier ones. Headlights ought to be OK with 2mm but if you've got room for 3mm then why not?

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Just the job. Will get some cables ordered and get on with it.

While on the subject of electrics, I think that my ignition problems mentioned earlier in this thread are down to the Sparkrite X1000 electronic ignition system which I recently praised so highly on another thread, also pointing out that my praise would put the kiss of death on it!! Went out for a good run yesterday with a view to being able to put my foot down and got an intermittent misfire. The beauty of the X1000 is the ability to switch from electronic to conventional which I did on the way back and suddenly no problems. So I'm now looking for a replacement, an X2000 or X4000. Has anyone got any experience of either of these. I don't want a permanent fixture unit as I want to be able to switch back to conventional in the case of the failure of the electronic unit (just like this case). Yes, paranoid I know, but the provision of switching helps settle what piece of mind I have left!!

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5 minutes ago, Pete Lewis said:

 

surely this unit just gets  a trigger by the orig  points so theres little improvement  other than reduce points current and wear.

if you stick to points theres no guess work on where the gremlin lies 

Pete 

Not sure if it doesn't increase the current to the plugs, so better quality spark and stuff. There must be some good reasons for it!! Since I fitted it, all those years ago, the engine does appear to have run smoother with better fuel consumption, or may that's what I believe due to the marketing hype. Maybe Mark and the other electronics types will advise us.

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I have one of the old classic Sparkrite 2000 models, which I tried years ago on a Spitfire and it never seemed to make any difference, no matter which way it was switched.

I'll keep it as a bit of automemorabilia (however you spell that, souvenir or memento or whatever!) and maybe try it out some day in the future for fun. The more modern versions, SX2000 or SX4000 are miles ahead in terms of performance and electronics. According to the bumf they reduce the current at the points and so prevent premature wear, whilst compensating for the dwell angle and making it much more accurate.

The SimonBBC site says:

"In a traditional points system the points have to carry the full voltage of the ignition system. The point’s gap is critical as it determines the dwell time for the coil. This is the time the coil is connected to ground allowing it to charge between each firing, every time the points open and close a spark can often be observed, this can cause damage to the contact surface leading to failure. In addition the point’s heel is constantly wearing closing the point’s gap and altering the dwell causing reduced performance.

The Sparkrite SX4000 diverts the high electrical current away from the points and controls the dwell time electronically, constantly adjusting and giving the correct dwell time.

The points now only having to deal with a tiny current so will not burn and will last indefinitely. The point’s gap now only needs to be roughly correct, as dwell is now electronically controlled. It will only need very occasional adjustment to take up any wear of the heel."

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I've not used electronic ignition for years. Probably nigh on 30! Though the one I had fitted to my last beetle I think got moved to a friends Metro - which after about 20years in a garage was brought back to life a few weeks ago - and the electronics still works!

The only real benefit of one that uses the points, is that as said, less wear on the face of the contacts (The heal still wears though obviously!) and that the negative to the coil is broken much cleaner so the spark is in theory a bit stronger. Practical terms? Who knows!

I run traditional points in my Spitfire.

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Colin - Yes... that was the reason I fitted it in the first place.  Now I remember!!!  Looking at the stupidly low price of the SX4000 (currently <no pun intended> £29.95 on the SimonBBC fleabay page) I think its worth the investment to bring the electronics up to date, even if I'm wrong about the misfire. The thing I liked about the SX1000 (and now the SX4000) is the ability to switch back to conventional when (not if) the unit fails. Much easier than some of the other units I've looked at. I suppose the low voltage thing on the points is just like the relay to the headlights that I have just fitted, which I thoroughly recommend (thanks Doug.. I believe that I read it first from you), especially for under a tenner.

Mark - Many thanks for your insight.

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The simple ones (probably includes the SX1000) are just a current amplifier, so the only effect is to reduce points wear. Perhaps a marginal improvement in turn off, which might make a tiny difference to the spark. The adblurb Colin quoted suggests that the SX4000 also delays or promotes the turn on time, so that the dwell period is more consistent across engine operating conditions. This might make for better spark at high speed and save a bit of wasted energy at low speed.

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I think the idea with these systems, inductive and capacitive, was that power was stored up in the bit of kit (SX1000 or 2000) to be discharged through the coil when triggered by the points so giving a better spark. They actually changed the way the coil was being used from inducting the spark due to collapsing its magnetic field by cutting the current flow through the points to inducting it by a rapid discharge of current through it. Anyway the idea seemed to fall out of favour (not sure if Pertonix still use it though) and we went back to the original simpler/cheaper arrangement but with electronics used to cut the flow of current rather than points (SX4000, Lumenition and Accuspark etc). 

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13 minutes ago, johny said:

I think the idea with these systems, inductive and capacitive, was that power was stored up in the bit of kit

That's only true of the ones that are described as "discharge", usually "capacitor discharge ignition" or CDI. Most work by the usual method of conducting current through the coil, but using a transistor to carry that current instead of the points. There's no "power storage" (which is a non-sequitur anyway - you can't store power, you can only store energy </pedant>).

CDI should normally want a change of coil, and gives higher spark voltage but normally shorter duration, which may not be a benefit.

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Just what I was hoping for from you all.  This forum never fails to impress. So, its 'can of worms' time Gentlemen (and any Ladies reading - of course) do we like these units and is the SX4000 worth trying for its silly price, assuming, of course that it give no improvement other than a better spark, less wear on the points and a smoother ride.  Not much to ask I know, but I'm sure that you will all rise to the challenge and that views will be mixed.

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Fitted a cheap E.I to car about 4 years ago. No difference to running, fuel consumption that I could tell.

After a few months I did change back to points as was having some running issues, though may NOT have been down to the E.I.

I fitted NOS points (and condenser). Car not missed a beat in 8000 miles from ignition system (apart from a couple plug failures with modern plugs).

Have kept the dizzy cam supplied with a bit of grease and not had to re-gap the points in this time. Also no sign of a pip on the points as of yet.

Dave

     

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I can confirm that the SX1000 was labelled Inductive Discharge and the SX2000 Reactive Discharge but the SX4000 is just a common or garden electronic points system and hence its cheapness. I think I fancy the SX5000 with built in adjustable rev limiter.... 

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So, back to the plot and the leaf spring mentioned earlier.

The first thing that I noticed was that only one of the screws on the access panel above the spring were doing anything... good start.  It gets worse.

Unfastened the eye bolts and drew out the four bolts holding down the spring and retaining box and found this..._MG_6380a.thumb.jpg.bb7cb3f54df26d2a49856ed059c9be23.jpg

At first glance not as bad as I expected

_MG_6381a.thumb.jpg.3425669b7df5a44ff767d7958fbe34a0.jpg

Until you start to look closely

_MG_6382a.thumb.jpg.0903227f3080862c0bf1e5032f0064f9.jpg

The retaining box is off center and the plate was fitted under the spring and not through it (well spotted Pete). You can clearly see the impression of the stud in the plate

_MG_6384a.thumb.jpg.54ecc68ffc57478e3ab604a24563aa3c.jpg

And as for the plate

_MG_6387a.thumb.jpg.e74f17724a9c922d5486372ea4e23d6f.jpg

... which I doubt that I can flatten easily....

_MG_6388a.thumb.jpg.61a44f268f2afaab01cdcd77cdcf1c70.jpg

in order to get it through the two spring leaves.

I am in two minds as to whether to take it back to the garage that fitted it and moan or just do my best to make good. I have not yet unfastened the nut holding the box onto the spring until I have decided what to do regarding the garage that fitted it!! I was unsure about the clips holding the spring leaves together but other photos on the net show the same layout. There must be some reason for this, but it looks strange.

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I wouldn't mess about, Canley's sell the plate £14.49. A bit concerned that the whole thing has got distorted by this, the "wavey" plate on the top doesn't look quite symmetrical, but proper installation might pull it all back? That pin also looks burred on the end and will need sorting out.

Doug 

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That really was fitted by a gorilla! Astonishing. I'm not quite sure how it's possible to assemble the spring with the bolt that goes through the cage off-centre to the bottom leaf, since surely it must fit in the hump in the next leaf?

Do the swing springs normally have different numbers of clamps on each side?

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So, according to the post counter, this is my 1000th post, so I will use it to post the final details of the damage done in the gorilla (sic) warfare against my suspension. I have decided to bite the bullet and not go back to the garage as it was nearly two years since they butchered the job. I will (thanks Doug) get some replacement parts from Canleys and know that the job is safe.

Took off the box retainer and found this...

_MG_6389a.thumb.jpg.1d1756db639629c5b81ff1de5f2adad8.jpg

and finally this (I have not yet taken out the crush tube)...

_MG_6391a.thumb.jpg.af8a7330db9a5c23b0782b8ae3d72e34.jpg

I would appreciate your comments and, as normal, any words of wisdom before I tackle the damage.  I assume that to fit the plate and bolt tube, I have to disassemble the spring and carefully put it all together.. properly before offering it back to the car.

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I think you'll be able to reuse all the leaves and probably the upper box bit (it's got an ovalled hole but that may not be too disastrous). You definitely need a new bottom plate, through bolt and crush tube.

As you say, fitting them will involve removing all the clamps, dismantling the spring completely, then building it back up in the correct order.

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