• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

FYI-How to find out if you MG is pos ground

mightymidget

Jedi Knight
Offline
As I mention I purchased a dead 67 MG Midget, and was wondering how to know for sure if it was postive earth, or if it had been switched over.

1. Electric Fuel Pump will only work if battery is hooked up correctly.
2. How the coil wire is hooked up to distributor, coil neg leg to distributor for negative ground cars

I am sure there are more, but these I have found once I started working on car
 
D

Deleted member 8987

Guest
Guest
Offline
Unless someone swapped coils trying to get it to start, and possibly a fuel pump.
SU Pumps, often, if connected backwards, SMOKE.
I have seen some with coloured tape around the parting line to indicate internal polarity.
 

jvandyke

Luke Skywalker
Offline
I thought I read somewhere the pumps are color coded for polarity, blue means positive earth or something like that? Don't quote me.
 
D

Deleted member 8987

Guest
Guest
Offline
That's the tape.
I THINK mine was red.....and it was part numbered "positive ground", for a car converted to negative.....and it was toast, yet only 6 months old.
The polarity-sensitive part inside (diode for arc suppression, I think) is a blackened mass, and the plastic that held it was melted pretty good.
 

Legal Bill

Jedi Knight
Country flag
Offline
tomshobby said:
Check your battery cables. Does the cable on the positive post or the negative post go to ground.

:lol: I was going to say that earlier but figured It was too mean. I assume the owner has a car that came with no battery and he wants to figure out the ground before he puts one in.
 

Legal Bill

Jedi Knight
Country flag
Offline
Along similar lines, though, the battery cable ends are usually different sizes becuase the posts of the batteries are different sizes for negative and positive. Trouble is, I can't recall which is the big side and which is small.
 
D

Deleted member 8987

Guest
Guest
Offline
If you had followed this saga, he bought the car, actual year and marque is under discussion.
It was grounded wrong for what he THOUGHT it was, but maybe not for what it might end up being.

He was trying to figure if the PO had hooked up correct or backwards.

Quite a thread, it was.

Oh......battery cables not necessarily different sized...when new replacements are installed.
That happens once you tighten them down (not the "hat" style).

To give you an idea:

My LBC is a 1964.
Originally positive earthing.

Ah, but it was negative earth when it arrived on scene.
Now, I am not going to just swap parts or polarity until I KNOW what is up.

Good thing, too.

The car had AC, as it was from Singapore.....
When I yanked the AC out several months after I started driving it, lo, and behold, there was a Lucas Alternator under the compressor, NOT the Generator I would have imagined (stock).

Had I just swapped around cables, I would have had smoke, and lots of it.

The clock it toast, but I have a spare to get re-worked for negative earth.
The aftermarket radio would smoke on positive earthing.
Fuel pump, see previous.

Could you tell from the battery cables?
Nope, as they had been tightened for negative earthing.
 
Similar threads
Thread starter Title Forum Replies Date
HealeyPassion FYI - AH BJ8 super car for sale Austin Healey 3
DrEntropy E-Type windshield FYI: Jaguar 1
Editor_Reid FYI re "What Did You Do On Your Austin Healey Today?" Austin Healey 0
MikeAH100M FYI - Hardie Board for Heat Shields not Recommended Austin Healey 9
tr6nitjulius TR5/TR250 FYI: Ford Blue 250/6 Triumph 12
T Clutch Issues continue. FYI Triumph 4
T cast iron welding info and repair-FYI Triumph 1
jaegzie Triumph Bike Owners and others, FYI on Triumph mag British Motorbikes 1
T TR6 FYI on TR6s for sale Triumph 2
theleisure FYI, "Bugeye Racer" on Bringatrailer Spridgets 1
steveg FYI--Needle comparison website Austin Healey 4
prb51 TR2/3/3A FYI TR3 Brake Caliper Seals/Pistons Triumph 0
JPSmit FYI - LBC heaven - consolation trip Spridgets 10
soren_ak Dont kno if ya seen this but here is FYI Austin Healey 1
B Moss Orders FYI Spridgets 16
t8nwa Spitfire FYI - Miata seats in a Spitfire 1500 Triumph 5
RickB Bugeye grille on ebay - FYI Spridgets 10
T FYI - Carb cleaner and IBM laptops don't mix Triumph 5
Alan_Myers Wedge FYI '81 Triumph TR-7 Convertible - $875 runs/drive Triumph 5
Alan_Myers Spitfire FYI - "Like new" '73 Spitfire, SF Bay area, $4500 Triumph 10
JPSmit FYI - engine for sale? Rover / Land Rover 1
JPSmit FYI Tiger Sunbeam (Rootes) 8
3798j Barn Find 200+ Cars Other Cars 3
Jim_Stevens TR6 Barn find of TR6 and many TR3 parts Triumph 9
T Storing nuts and bolts (so you can find what you need) Austin Healey 7
Bob Claffie MGA Almost barn find MG 1
T BJ7 Hard to find First Gear when G/Box is hot Austin Healey 3
Basil Spitfire 74 Spitfire Barn Find Triumph 1
Rob Glasgow Can I find Another one as Good? Austin Healey 4
C My BJ8 Barn Find Austin Healey 15
F General MG Field find restoration question ... MG 5
S For Sale RARE FIND BN2-BT7 and? Trans Parts for Sale Austin Healey Classifieds 2
W Find gearbox rebuild [2nd synch shot] South. California Jaguar 1
F 1960 FriskySport Barn Find Other British Cars 6
K For Sale TR3 Engine Lift Bracket...hard to find! Triumph Classifieds 0
R J-H rear transmission seal? Why can't I find it on the web? Other British Cars 1
Alfred E. Neuman General TR Hemmings find of the day Triumph 1
T can't find timing marks on 1275 crankshaft pulley/damper Spridgets 8
D T-Series Trying to find out an interior dimension MG 7
T Trying to find an accurate tyre pressure gauge Spridgets 24
C Garage find '65 XKE Jaguar 12
C Someone can help me to find it Austin Healey 6
HealeyRick Rare Barn Find Valve Cover Racer Austin Healey 9
glemon TR6 Barn Find TR6 Triumph 9
R Questions about a barn find Austin Healey 18
T SE Massachusetts BN1 barn find Austin Healey 15
S Open a ingnition key barrel to find the key number. Restoration & Tools 2
tinman58 TR2/3/3A Barn Find Triumph 19
Jim_Gruber Did I find another need for a Whitworth Wrench Set/ Did I screw up intake manifold Spridgets 5
J MGB "warehouse find" MG 14

Similar threads

Top