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sabot
09-23-2008, 05:52 PM
ok, stupid question time,
on the 67 spitfire i just picked up,

the negative cable is going to the starter relay and the positive cable is going to the frame.

Is that correct? or how can i tell for sure thanks tom

DNK
09-23-2008, 05:54 PM
Positive ground

MGTF1250Dave
09-23-2008, 07:20 PM
I concur with Don. Positive ground (earth) is typical of British cars of that vintage.

TR3driver
09-24-2008, 01:24 AM
It almost doesn't matter unless originality is a concern, or someone has fitted some electronic components to the car. The ignition coil is the only original component that is polarity-sensitive; and it's easy enough to swap the wires at the coil. (Also won't hurt anything if it's wrong, just might not run quite as well.) Personally, I'd probably convert anyway, just so I didn't have to worry about it being different, could fit an alternator or stereo if I wanted, etc.

But I agree with the others, Spits stayed positive ground (positive cable to the frame) until the Mk IV (1970) even though TRs went negative ground in 65.

sabot
09-24-2008, 09:05 AM
thanks for the info guys,

one more stupid question, if i leave it positive ground, will that be a problem if i ever have to jump start it?

brain dead after all these years, tom

Andrew Mace
09-24-2008, 11:09 AM
I (reluctantly, since I don't have my manuals in front of me!) beg to differ. I'm pretty sure that most, if not ALL, Mk3 Spitfires, were negative ground. I believe the change occurred in 1967, possibly coincident with the introduction of the Mk3.

I'll try to double-check this tonight at home. Meanwhile, if anyone has a later edition of the factory workshop manual for the Herald/Vitesse/Spitfire, it does tell there.

Meanwhile, jump starting is not a problem regardless, so long as you make sure + goes to + and - goes to -.

sabot
09-24-2008, 11:18 AM
thanks andy,,,so now i got a few question on starting this baby up.
do i start a new posting?

TR4
09-24-2008, 11:45 AM
You would get a better response if you start another posting so the title reflects your issue.

TR3driver
09-24-2008, 04:31 PM
Meanwhile, if anyone has a later edition of the factory workshop manual for the Herald/Vitesse/Spitfire, it does tell there.I do (although it's the Brooklands reprint, magnifying glass not included) and in fact was looking at it (with magnifying glasses <<GRAEMLIN_URL>>/grin.gif ) when I wrote the above post.

TR3driver
09-24-2008, 05:04 PM
if i leave it positive ground, will that be a problem if i ever have to jump start it?Just be certain there is no other conduction path between the two vehicles (like the bumpers touching) and it will be fine.

Andrew Mace
09-24-2008, 06:30 PM
Meanwhile, if anyone has a later edition of the factory workshop manual for the Herald/Vitesse/Spitfire, it does tell there.I do (although it's the Brooklands reprint, magnifying glass not included) and in fact was looking at it (with magnifying glasses <<GRAEMLIN_URL>>/grin.gif ) when I wrote the above post. Interesting, since my original (black vinyl binder) Workshop Manual has a specific "Section 3" in "Group 6 (electrical...)" stating: "Information contained in this section deatils electrical equipment specific to the following vehicles that are all fitted with a negative earth electrical system.

Herald 1200 from approximately March 1968
Herald 13/60 introduced in October 1967
Spitfire Mark 3 introduced in March 1967."

Is there something different in your Brooklands reprint, or did I miss something in a smiley? :confuse:

TR3driver
09-24-2008, 06:38 PM
I'll have to check it when I get home tonight. I was looking at a wiring diagram labelled "Spitfire Mk III" that showed the battery positive connected to ground.

Dunno what happened to the black one, must've let it go with the Sports 6.

Andrew Mace
09-24-2008, 06:44 PM
Not to belabor the point, but the Spitfire Mk3 Spare Parts Catalogue, Second Edition, lists part number 515997 -- Lead, battery negative to body to engine earth lead, and part number 516873 -- Lead, battery positive to solenoid. Puzzling, meanwhile, about that wiring diagram; does it have a page number?

TR3driver
09-25-2008, 12:14 AM
Boy, do I feel stupid !

You're absolutely right, Andy ... checked the diagram again and it does show negative ground.

Oops!

Andrew Mace
09-25-2008, 08:52 AM
Oops!Not to worry; we're all allowed the occasional gaffe! Maybe you do need a bigger magnifying glass, though. For the life of me, I don't know why those reprints are done half-size. Yeah, I understand saving money, but we older folk still working on these older cars need bigger print. :crazyeyes:

sabot
09-25-2008, 10:52 AM
hi guys,

positive to ground, negative to solinoid is the way it is set up.

but the book says it might not be that way?
did they do it as positive ground up to March 67, then change to negative ground?
sorry, i'm not sure how you guys include statemants from previous posts.
cut and paste?
tom

DNK
09-25-2008, 11:02 AM
Tom , Just go to the post you want to quote and hit the Quote or Quick Quote button.

sabot
09-25-2008, 11:09 AM
Tom , Just go to the post you want to quote and hit the Quote or Quick Quote button.

hey it works.
thanks don

DNK
09-25-2008, 11:38 AM
Would steer ya wrong.

Lots easier now than it use to be.

TR3driver
09-25-2008, 12:27 PM
positive to ground, negative to solinoid is the way it is set up.

but the book says it might not be that way?
did they do it as positive ground up to March 67, then change to negative ground?Well, Andy's quote would make it appear that all Mk 3 Spits were negative ground. That doesn't mean there weren't some positive ground Mk 2s titled after March 67, though; or possibly even a "personal export" Mk 3 that got titled before then.

So the question becomes whether your car is a Mk 3. What's your commission number (VIN) ?

Andrew Mace
09-25-2008, 01:53 PM
As I've already noted, factory information does seem to confirm that all Mk3 Spitfires were negative ground. But there are some sources around the Net that seem to indicate that the Mk3 dates from January 1967 (I've nothing in front of me to confirm or dispute that date), so ??? Your car is pretty early (FD2081?), but.... ?

I'm guessing that the cables are not original Lucas "Helmet" style terminal ends? A: they usually were clearly marked + or -, and B: they're usually a slightly different size (+ terminal a tiny bit larger, as I recall). If the cables are generic replacements, it's certainly possible that someone reversed a battery sometime in the last 40 years.

Also not conclusive after 40 years, but how are the small wires on the coil connected? Ideally, the small wire from coil to terminal would come from the - side of the coil on a negative ground car. Yes, the car will run either way, but generally it runs better when the coil is wired properly.

TR3driver
09-25-2008, 05:16 PM
But there are some sources around the Net that seem to indicate that the Mk3 dates from January 1967My understanding is that March was the 'official' introduction date in the US, even though the first Mk3 cars were produced several months before that (ie January).

Given the US dealers' propensity for selling next year's cars starting in October (or even earlier), that would make almost 6 months worth of "1967" Mk 2s.

TR3driver
09-25-2008, 05:18 PM
Maybe you do need a bigger magnifying glass, though.More likely, I should quit buying them at the $.99 store <<GRAEMLIN_URL>>/grin.gif

sabot
09-25-2008, 09:37 PM
hi randall,

i find that in my line of work, the cheap glass of the corner store seem to work the best.
the commission number is fd 2081 L, with a body number of 2264fd .

as far as the coil go's, the negative wire is going to the generator,
and the positive go's off into the harness into the firewall.

tom

TR3driver
09-26-2008, 12:07 AM
as far as the coil go's, the negative wire is going to the generator,
and the positive go's off into the harness into the firewall.
Assuming you mean distributor instead of generator, that would indicate the coil is wired for negative ground; and someone has installed the battery backwards.

If you switch it back, you'll probably have to repolarize the generator, but nothing else should be required.

sabot
09-26-2008, 07:31 AM
as far as the coil go's, the negative wire is going to the generator,
and the positive go's off into the harness into the firewall.
Assuming you mean distributor instead of generator, that would indicate the coil is wired for negative ground; and someone has installed the battery backwards.

If you switch it back, you'll probably have to repolarize the generator, but nothing else should be required.

oops, yer right, i meant distributor.

how doe's one repolarize a generator?
tom

Andrew Mace
09-26-2008, 10:19 AM
how doe's one repolarize a generator?
tom Sometimes, they'll repolarize themselves. Best, though, to follow the directions on the VTR site (https://www.vtr.org/maintain/negative-ground.shtml) . Actually, you should only need to do the last two steps.

sabot
09-26-2008, 10:29 AM
hi andy, and thanks. and yes i am a member of the VTR.
tom

TR3driver
09-27-2008, 12:26 AM
I'm not sure how your Spit is arranged, but usually, you can just pull the wire off the 'F' terminal on the regulator and brush it against the 'A' or 'A1' terminal. No need to have the engine running or ignition on. You might see some modest sparks, that's OK. Put the wire back on the 'F' terminal, start the engine and see if the generator light goes out. If so, all is well.

But if it's like the Sports 6, where the regulator is under the dash, then it's probably easier to momentarily connect a jumper from the battery to the 'F' terminal on the generator.