New Car - Electrical Problem

... well new to me and given the next question it's actually not that
new.

This is it:
http://www.sweller.dynalias.org/images/DSCF5070sml.jpg [1]

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".

 

Looks lovely Simon.

 

took a blunt brush and painted...

Mount them onto an isolated mounting plate, you can then keep them as
positive earth whilst rest of the car is -ve earth.

You won't need to if you change it round.

 

hah.

that's perfect.

 

The thought of maintaining something like that makes my blanche.

 

I'm not sure I'd fancy doing that, assuming they're metal bodied and
there's petrol in the near vicinity.

 

Yes, an idea, but vastly increases risk of shorts 'n' fires.

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-200808131509358066.htm
"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?

The SU web site has some material on "electronic"
pumps. Guess no points. Old ones are polarity
sensitive.
http://www.sucarb.co.uk/TechnicalDetail.aspx?id=34

http://www.mgexperience.net/article/su-fuel-pumps-101.html
Says that diodes were introduced in the mid '60s
so maybe you have such a pump. Would seem a reasonable
proposition to turn it round.

Connecting a diode equipped pump the wrong way round
might well break it.

 

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.

 

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.

 

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.

 

Very nice.

S-Type, yes?

You want a Becker Mexico once you sort out the polarity stuff.

Not cheap, but look the part and are an excellent unit.

I see your definition of subtle differs from mine....

 

I reversed the polarity on my moggy minor and the good old SU leccy
fuel pump just kept ticking away happily.

BTW, you are a ****. I would love a Mk2 Jag

--
Dan L

Too much time to think, too little to do.


http://thebikeshed.spaces.live.com/

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)

BOTAFOT #140 (KotL 2005/6/7/8)
X-FOT#000
DIAABTCOD #26
BOMB#18 (slow)
OMF#11

 

You are right, it is an S Type, not a Mk2.

Front indicators give it away.

--
Dan L

Too much time to think, too little to do.


http://thebikeshed.spaces.live.com/

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)

BOTAFOT #140 (KotL 2005/6/7/8)
X-FOT#000
DIAABTCOD #26
BOMB#18 (slow)
OMF#11

 

I dunno. No £900 ignition modules to pay for.

 

OK, I think you owed me one.

 

Oh you ****, I hate you even more now.

I fucking love S-Types.

 

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.

 

Seconded. That looks fucking gorgeous.