I've had a fair few positive earth cars in the past but converting this one maybe a bit tricky. The clock isn't fussy about polarity (as the parts books give the same number for both types) and the tacho relies on a small AC generator which is isolated from the rest of the car electrics.
The fuel pumps are the problem, they seem to be polarity dependent and they're not cheap - are they something that could be readily converted or is it bite the bullet and buy two negative earth ones?
Getting a positive earth radio with FM is a bit of an arse.
[1] see that, that's a subtle bit of willy waggling.
> I've had a fair few positive earth cars in the past but converting > this one maybe a bit tricky. The clock isn't fussy about polarity (as > the parts books give the same number for both types) and the tacho > relies on a small AC generator which is isolated from the rest of the > car electrics.
> The fuel pumps are the problem, they seem to be polarity dependent and > they're not cheap - are they something that could be readily converted > or is it bite the bullet and buy two negative earth ones?
> Getting a positive earth radio with FM is a bit of an arse.
> [1] see that, that's a subtle bit of willy waggling.
Nice motah. Really, really, very nice and so "you".
swel...@mztech.fsnet.co.uk took a blunt brush and painted...
> The fuel pumps are the problem, they seem to be polarity dependent and > they're not cheap - are they something that could be readily converted > or is it bite the bullet and buy two negative earth ones?
Mount them onto an isolated mounting plate, you can then keep them as positive earth whilst rest of the car is -ve earth.
> Getting a positive earth radio with FM is a bit of an arse.
TOG@Toil wrote: > On 9 July, 09:42, sweller <swel...@mztech.fsnet.co.uk> wrote: >> .. well new to me and given the next question it's actually not that >> new.
>> I've had a fair few positive earth cars in the past but converting >> this one maybe a bit tricky. The clock isn't fussy about polarity (as >> the parts books give the same number for both types) and the tacho >> relies on a small AC generator which is isolated from the rest of the >> car electrics.
>> The fuel pumps are the problem, they seem to be polarity dependent >> and they're not cheap - are they something that could be readily >> converted or is it bite the bullet and buy two negative earth ones?
>> Getting a positive earth radio with FM is a bit of an arse.
>> [1] see that, that's a subtle bit of willy waggling.
> Nice motah. Really, really, very nice and so "you".
The thought of maintaining something like that makes my blanche.
On Thu, 9 Jul 2009 10:42:51 +0100, frag squeezed out the following:
>swel...@mztech.fsnet.co.uk took a blunt brush and painted...
>> The fuel pumps are the problem, they seem to be polarity dependent and >> they're not cheap - are they something that could be readily converted >> or is it bite the bullet and buy two negative earth ones?
>Mount them onto an isolated mounting plate, you can then keep them as >positive earth whilst rest of the car is -ve earth.
I'm not sure I'd fancy doing that, assuming they're metal bodied and there's petrol in the near vicinity.
> swel...@mztech.fsnet.co.uk took a blunt brush and painted...
> > The fuel pumps are the problem, they seem to be polarity dependent and > > they're not cheap - are they something that could be readily converted > > or is it bite the bullet and buy two negative earth ones?
> Mount them onto an isolated mounting plate, you can then keep them as > positive earth whilst rest of the car is -ve earth.
Yes, an idea, but vastly increases risk of shorts 'n' fires.
> > Getting a positive earth radio with FM is a bit of an arse.
> You won't need to if you change it round.
Hmm - SU fuel pump polarity sensitive?
Lump of iron and coil of wire seems the most likely operating materials. I suppose they *could* have used a magnet but why would they bother? Would only wear out. My guess is that an original 1965 (assuming original reg and not vanity plate) pump would not be polarity sensitive.
http://www.british-cars.net/mga-bbs/su-fuel-pump-rebuild-200808131509... "Stock SU fuel pumps were not polarity sensitive so no changes need to be made. Pumps fitted with a diode are polarity sensitive and the diode has to be re-oriented. After you re-build the pump measure the pressure and flow. Then you'll know!"
Not sure what the diode might have been for, maybe EMI reduction? Or maybe to extend the life of the points?
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember sweller <swel...@mztech.fsnet.co.uk> saying something like:
>The fuel pumps are the problem, they seem to be polarity dependent and >they're not cheap - are they something that could be readily converted >or is it bite the bullet and buy two negative earth ones?
You don't have to buy SU pumps - plenty of other options. Anyway, have you actually tried them the other way round? Istr the fuel pump on Moggies was not an issue when doing a changeover.
Grimly Curmudgeon wrote: > We were somewhere around Barstow, on the edge of the desert, when the > drugs began to take hold. I remember sweller > <swel...@mztech.fsnet.co.uk> saying something like:
>> The fuel pumps are the problem, they seem to be polarity dependent and >> they're not cheap - are they something that could be readily converted >> or is it bite the bullet and buy two negative earth ones?
> You don't have to buy SU pumps - plenty of other options. > Anyway, have you actually tried them the other way round? Istr the fuel > pump on Moggies was not an issue when doing a changeover.
I certainly would research the pumps and perhaps even disassemble one before simply applying reverse polarity, at best, you'd pop a diode and at worst you'd fry a whole circuit board, depending on which type of pumps he has.
I would agree that if the pumps are indeed polarity sensitive, and aren't amenable to modification, the most straightforward approach would be to fit some aftermarket pumps or even a single pump. My old MGBs were much better off with anything other than the original pump, and as I remember converting my '65 MGB from positive earth to negative, I didn't touch the aftermarket pump that was in there, and it continued to work fine after the switchover. For all I know it did have a diode which I popped but I didn't run it enough afterward to discover that the contacts were eroding away at a fast clip.
> I've had a fair few positive earth cars in the past but converting > this one maybe a bit tricky. The clock isn't fussy about polarity (as > the parts books give the same number for both types) and the tacho > relies on a small AC generator which is isolated from the rest of the > car electrics.
> The fuel pumps are the problem, they seem to be polarity dependent and > they're not cheap - are they something that could be readily converted > or is it bite the bullet and buy two negative earth ones?
> Getting a positive earth radio with FM is a bit of an arse.
> [1] see that, that's a subtle bit of willy waggling.
We always used to use Facet fuel pumps on the sidecarp, they seemed to have a fuel pump for every application, might be worth a google.
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Mark Olson <ols...@tiny.invalid> saying something like:
>I certainly would research the pumps and perhaps even disassemble one >before simply applying reverse polarity, at best, you'd pop a diode >and at worst you'd fry a whole circuit board, depending on which type >of pumps he has.
He made no mention of them being updated, but who knows. Assuming it's still the orignals, we're talking 1960s push-pull simple tech which isn't polarity sensitive. Here's a way of improving the reliability of them if originality is important. http://www.mgccq.org.au/tech4.htm Actually, you can buy a very nice Kraut pump of the same overall design, made by Buggeredifirecall, but I've got one on the SOJC. Facet pumps are universally available, of course.
Grimly Curmudgeon wrote: > We were somewhere around Barstow, on the edge of the desert, when the > drugs began to take hold. I remember Mark Olson <ols...@tiny.invalid> > saying something like:
>> I certainly would research the pumps and perhaps even disassemble one >> before simply applying reverse polarity, at best, you'd pop a diode >> and at worst you'd fry a whole circuit board, depending on which type >> of pumps he has.
> He made no mention of them being updated, but who knows.
What I meant to say but left off was "if indeed the pumps are polarity sensitive".
> Assuming it's still the orignals, we're talking 1960s push-pull simple > tech which isn't polarity sensitive. Here's a way of improving the > reliability of them if originality is important. > http://www.mgccq.org.au/tech4.htm > Actually, you can buy a very nice Kraut pump of the same overall design, > made by Buggeredifirecall, but I've got one on the SOJC. Facet pumps are > universally available, of course.
Someone who should have known better has fried more electrical doohickery than he likes to admit, and is now just a _little_ bit more cautious, esp. when dealing with something that might have had many hands touch it over the years.
> I've had a fair few positive earth cars in the past but converting > this one maybe a bit tricky. The clock isn't fussy about polarity (as > the parts books give the same number for both types) and the tacho > relies on a small AC generator which is isolated from the rest of the > car electrics.
> The fuel pumps are the problem, they seem to be polarity dependent and > they're not cheap - are they something that could be readily converted > or is it bite the bullet and buy two negative earth ones?
> Getting a positive earth radio with FM is a bit of an arse.
You want a Becker Mexico once you sort out the polarity stuff.
Not cheap, but look the part and are an excellent unit.
> [1] see that, that's a subtle bit of willy waggling.
I see your definition of subtle differs from mine....
-- SteveH 'You're not a real petrolhead unless you've owned an Alfa Romeo' Alfa 156 TSpark Sportwagon Veloce Selespeed - Alfa 75 TSpark Lusso - Ducati 750SS - BMW R100RT - Toyota Prius T-Spirit
> I've had a fair few positive earth cars in the past but converting > this one maybe a bit tricky. The clock isn't fussy about polarity (as > the parts books give the same number for both types) and the tacho > relies on a small AC generator which is isolated from the rest of the > car electrics.
> The fuel pumps are the problem, they seem to be polarity dependent and > they're not cheap - are they something that could be readily converted > or is it bite the bullet and buy two negative earth ones?
> Getting a positive earth radio with FM is a bit of an arse.
> [1] see that, that's a subtle bit of willy waggling.
I reversed the polarity on my moggy minor and the good old SU leccy fuel pump just kept ticking away happily.
1992 kawasaki ZXR400 (The one wiv the hoover tubes) Coming soon to a patio near me. 2003 Ducati 900SS FF (Woo hoo) 2002 Triumph Sprint RS 955i (BTDT) 1996 Kawasaki ZR1100 Zephyr (Gone, but not forgotten)
> > I've had a fair few positive earth cars in the past but converting > > this one maybe a bit tricky. The clock isn't fussy about polarity > > (as the parts books give the same number for both types) and the > > tacho relies on a small AC generator which is isolated from the > > rest of the car electrics.
> > The fuel pumps are the problem, they seem to be polarity dependent > > and they're not cheap - are they something that could be readily > > converted or is it bite the bullet and buy two negative earth ones?
> > Getting a positive earth radio with FM is a bit of an arse.
> You want a Becker Mexico once you sort out the polarity stuff.
> Not cheap, but look the part and are an excellent unit.
> > [1] see that, that's a subtle bit of willy waggling.
> I see your definition of subtle differs from mine....
1992 kawasaki ZXR400 (The one wiv the hoover tubes) Coming soon to a patio near me. 2003 Ducati 900SS FF (Woo hoo) 2002 Triumph Sprint RS 955i (BTDT) 1996 Kawasaki ZR1100 Zephyr (Gone, but not forgotten)
Hog <hogS...@freenetCHIPS.co.uk> wrote: > > Nice motah. Really, really, very nice and so "you".
> The thought of maintaining something like that makes my blanche.
I dunno. No £900 ignition modules to pay for.
-- BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple Suzuki TS250ER Coo, down to just five bikes! If you don't know what you're doing, don't do it. And RTFM. chateau dot murray at idnet dot com
> I've had a fair few positive earth cars in the past but converting > this one maybe a bit tricky. The clock isn't fussy about polarity (as > the parts books give the same number for both types) and the tacho > relies on a small AC generator which is isolated from the rest of the > car electrics.
> The fuel pumps are the problem, they seem to be polarity dependent and > they're not cheap - are they something that could be readily converted > or is it bite the bullet and buy two negative earth ones?
> Getting a positive earth radio with FM is a bit of an arse.
> [1] see that, that's a subtle bit of willy waggling.
Dan L wrote: > You are right, it is an S Type, not a Mk2.
> Front indicators give it away.
The lack of a sidelight at the top of the wing gave it away for me. Also, a 1965 Mk2 wouldn't have skinny bumpers, they had the armco style ones until 1967, when they also changed the name to the 240 and 340, lowered the trim spec and dropped the 3.8 engines.
-- Lozzo Versys 650 Tourer, CBR600F-W trackbike, SR250 SpazzTrakka, SR250 wivva topbox, TS250C, RD400F (somewhere) Garage clearout - two Yamaha SR250s for sale, email for details
> The lack of a sidelight at the top of the wing gave it away for me. > Also, a 1965 Mk2 wouldn't have skinny bumpers, they had the armco style > ones until 1967, when they also changed the name to the 240 and 340, > lowered the trim spec and dropped the 3.8 engines.
<also dons anorak>
It was the chrome headlamp surrounds that did it for me. -- SteveH 'You're not a real petrolhead unless you've owned an Alfa Romeo' Alfa 156 TSpark Sportwagon Veloce Selespeed - Alfa 75 TSpark Lusso - Ducati 750SS - BMW R100RT - Toyota Prius T-Spirit
I love the 'new' one. V8s are getting stupidly cheap these days, too. -- SteveH 'You're not a real petrolhead unless you've owned an Alfa Romeo' Alfa 156 TSpark Sportwagon Veloce Selespeed - Alfa 75 TSpark Lusso - Ducati 750SS - BMW R100RT - Toyota Prius T-Spirit
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