Classic cars forum & vehicle restoration.

[pigtin]

Hi
Dave is absolutely correct in his interpretation of Ohms law etc' and I must confess that I took a little too much at face value from the VW club article and the car owners at the show, who assured me that the mod had been working for them for years, rather than examine the theory in detail.

In theory the problems that Dave mentions are quite valid, but by the same theory a 6v system should perform adequately and not need modification. As a past owner of VWs and various 6v British cars I can assure you that it is not the case.
Although I never checked the (on load) voltage at the headlights of my VW I did on my Austin Seven and it was close to 4v: one has to take into account the drop across the wiring, there will also probably be some lost through the switch, connections and contacts; to say nothing about the drop you will get from the earth return.
In an ideal world there would be none of these losses, but it isn't an ideal world.
In a nutshell if 6v draws twice as much current as 12v, then the cables. switches and connections should have twice the current carrying capability. Have they? I've never really checked but I suspect not on European cars. On American cars, perhaps.

I was not aware that the tolerance of the lamps was so low I would have thought a 6v bulb with an upper limit of 6.75 was cutting it a bit fine, considering that the fully charged voltage of a 6v battery with the dynamo charging would possibly exceed that.

As far as I can see, Dave's theory is faultless, and I am not arguing with it, but in real life the mod would appear to work, both on the VWs I saw and on the Austin Seven I converted myself. But there may be unexpected pitfalls on other makes.

Don.

p s; Writing technical details from 'the top of ones head' is not to be recommended, hence the editing. Probably best not to get too technical in future.

[Uncle Joe]

UK: I can also run the ignition off 16v if I convert to something likre MSD, I believe.

Pigtin: I cant really say if american cars did or didnt have heavier gauge wiring. Without wishing to provoke anyone, and speaking from my own experiences, I've found that their systems to be well in advance of british (read: Lucas) of the same period. Alternators were standard in the early '60's, for example...and reliable alternators at that.

UJ

[UKdave2002]

My previous post was a bit of a technical lecture!! sorry Should have been tempered with some practical reality.

Cables are rated by size, so a 14/0.01 has 14 strands of 0.01inch diameter wire, has a rating of about 8 amps and a volt drop per foot of about 0.005V for every amp being carried. In many UK pre war cars headlamps were only 24W, over the year’s owners would put higher wattage bulbs in, say 36 or even a wapping 48watt!, the reality being that because of the increase in current drawn the volt drop in the wiring would be higher, the 8V system Don talks about could compensate for this, you wouldn’t design it from scratch that way, but it can work.

Regarding bulb output & life, I have got a table somewhere with the various applied voltages and corresponding outputs and life I’ll dig it out, but the figures that are etched on my mind because they were common auto electrical exam questions that as students we had rammed into us are;

25% overrating will give you double the output but less than 10% bulb life.
25% underrating will give you half the output but 1000% bulb life.

UJ regarding a 16V ignition system, you could do it but I wouldn’t expect much improvement over 12V, they key thing to improve in ignition is the speed of the magnetic field collapse in the coil, assuming the car you are thinking of modifying has a Delco points and condenser system, changing to an electronic version should give an improvement as the electronic “switch” is far cleaner than a set of points. If you have a high revving engine then an MSD capacitive discharge system may be right for you, I looked at CD systems when researching an electronic ignition for the Stag, yes they are good but unnecessary IMHO (unless you need constant high RPM) and expensive to maintain, I had an 1982 911 which has a CD system as standard, to maintain top performance things like ignition leads only lasted 18 months (and they were dam expensive!!).

Most of these systems (I don’t specifically know about MSD) are deigned to work at about 10V, so that they work well under starting conditions, there will be some form of voltage regulator in the system that takes the battery voltage down , so I wouldn’t expect any ignition advantage with 16V battery, unless you had it in some form of race car and were ditching the alternator to save power, in which case a 16V battery would give you a longer duration.

Dave

[Uncle Joe]

UK, the MSD system will work between 11 and 18volts continuously, with momentary voltages of 8 to 24.

The reason I am thinking MSD is because I know it to be a reliable system. The factory electronic ignition is known to have weak points.

UJ

[UKdave2002]

Hi UJ

I'd be interested to see how it perfoms on an older car. CD certainly is the best ignition system, my only concern would be that the other components like leads and dizzy cap etc are up to the job and wont need changing every few months.

Dave

[Uncle Joe]

UK, two secondes before you replying to this, I found a complete system, everything included for £150. I've just mailed, asking about the points you mentioned. Wonder what the answer will be?

UJ

[UKdave2002]

Chatting to a guy I know in our local last night, who works for a local tunning firm, recons MSD do there own dizzy caps (not sure if they cover older cars) and that you can get far better ignition wire than even a few years ago, so you could bet onto a winner UJ, he also said they would charge £200 + vat for the basic MSD CD system, so your price looks good too.

Dave

[Uncle Joe]

UK, one thing that is a surprise to me is that I can purchase an item in the US, ship it here, pay import duty and other taxes, and STILL undercut dealer prices both here and in the UK!

By recent experiences, this amounts roughly to a 25% saving. Whats wrong with European Companies?

UJ

[pigtin]

As someone who has spent a large slice of his life importing equipment from the U.S. I have to jump to the defence of the European suppliers.
OK you have one item sent in by (possibly) 'Air Parcel Post', sometimes the post office do not even remember to charge the VAT on it. I know because I try to import anything I can this way and even if they do charge VAT and import duty, it is no big deal.
It's when you start importing several items in a larger packages of well over 2kg that the charges go up, you have to import it through an agent, it will attract customs clearance charges and transport to the dispatching, and from the receiving airport. The goods will have to be paid for up-front and also the VAT before the agent will deliver them.
Then they will possibly sit on the shelf for months before they are bought.

In these days of credit cards it is a lot easier for individuals to import goods from the U.S. but remember the credit and currency change charges, and the time spent sourcing and ordering etc. These all have to be paid for by a stockist.
In all, If you are smart enough, import it yourself.

Having said all that, some stockists will charge excessively, but everyone is entitled to make a living.

Don.

[Uncle Joe]

3 weeks ago, I shipped in via Bax Global 1 item in a 65kg package. I got it in 4 days from California. That the same time as it would have taken from a local supplier.

I paid 25%VAT (local rates) plus 3,5% Import on everything, even the freight costs. It was still 25% cheaper than form the local people! And it is these people that I am annoyed with, not the 'honest' businessman! That for me is profiteering from them, especially when, here at least, freight and VAT is a tax deductible!

But, please note that I am just expressing an opinion based on my experiences, and DO NOT WISH TO OFFEND!

UJ

[pigtin]

Your'e right UJ, we use BAX Global ourselves and they are very reasonable, but if the 25% you speak of is all the profit your supplier is making, unless he was working with no overheads, he would very soon go out of business in the UK.

If it was a large expensive items 25% is bearable providing the item has not been sitting on the shelf for too long. One has to take into account how much the safety and employment laws cost a small company, and that is on top of taxes and the cost of borrowing money from the worst profiteers, BANKS! Of course every companies situation is different and I am not up-to-speed on the particular problems of Scandinavia, I seem to recall that our company in the UK can usually undercut Scandinavian prices in spite of sourcing from the same place.

I know exactly how you feel UJ and in a 'Free Trade' world, things should be different, but there are still far too many parasites taking their cut.

Sincere apologies UJ if I sounded pedantic in my previous post, it wasn't meant to be like that.
Don.

[1stpop]

does anyone know of a sight or place were I can get instructions for a 12v conversion - am really interested in being able to source the right parts - tha pop's fairly simple and appears to have modern wiring - just fed up with it not starting too well and little problems like that!!!

[UKdave2002]

Hi 1stpop

I don't think you are going to find a specific set of instructions, but if you post a list of all the electrical items in your car together with the regulator type, and dynamo type, I'll let you know what needs changing and what and how to modify the other bits.

Dave

[Rick]

If I get chance, I'll have a look through some old Ford Sidevalve OC magazines and see if there is anything there. In fact it might be worth considering joining this club if you plan to keep the Pop for a while

Rick
_________________
Rick - Admin
Home:https://www.oldclassiccar.co.uk
Videos:https://www.youtube.com/user/oldclassiccarRJ/videos
OCC & classic car merchandise (Austin, Ford ++):
https://www.redbubble.com/people/OldClassicCar/shop