Library: MGB FAQ

Should I buy an MGB?

If you love driving, and are willing to do or have done the (very reasonable) maintenance needed by a 20+ year old car, then absolutely yes! Read LBC: Fact and Fiction and my little essay in Buying Your MGB for the whole story. Both can be found in the Library of The MG Experience.

Common terms and acronyms:

(This list is far from complete!)

BFH	Big Freakin' Hammer. See also, BFS and Large Rock.
BFS	Big Freakin' Screwdriver. See also, BFH and Duct Tape.
BMIHT	British Motor Industry Heritage Trust. Maintains records of all the old British marques and is involved with pressing new bodyshells for some years and models. Located in/around Stratford, England I think.
Bondo	What many MGBs are held together with. See also Duct Tape.
CBB	Chrome Bumper (pre 1974½) MGB. See also RBB.
Blowby	Post-combustion gunk that gets from the combustion chamber past the piston rings and into the engine oil. Usually caused by broken rings or scored cylinder walls.
Crack of Doom	A common stress crack that develops on the door skins just behind the vent window. The only known design flaw in the MGB.
Death Rattle	Common to Midgets, a "marbles in the dryer" sound on startup that indicates your main bearings are on their way out.
Detonation	Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to ignite before the spark. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading. Avoid.
Dieseling	When your car continues to run after you've turned the ignition off. Caused by pressure and excess heat in the cylinders igniting the air fuel mixture without spark (like a diesel engine).
DPO	Dreaded Previous Owner, usually used when one finds a bodge or a hack used to cover up a problem instead of purchasing the correct part to fix it. Also used in conjuction with other adjectives when Bondo is discovered.
Duct Tape	The Handyman's Secret Weapon. The rear tail light had been held on by duct tape for years when I bought my LBC. See also DPO.
FAQ	Frequently Asked Questions
FWIW	For What It's Worth
HT	High Tension, or high voltage (20-40kV) half of ignition system comprising of coil secondary winding, distributor rotor and cap, spark plug wires, and spark plugs. See also LT.
IMHO/IMO	In My (Humble) Opinion
Knocking	A catch-all term which could mean Detonation or Pinging
Large Rock	A tool commonly available at the side of the road in the middle of the night when you need to "fix" something
LBC	Little British Car (or Convertible). MG, Triumph, Austin-Healey, Morgan, etc
LT	Low Tension, or low voltage (12V) half of ignition system comprising of coil primary winding, distributor points (or equivalent), electric tachometer, and possibly ballast resistor. See also HT.
Lucas	The manufacturer of most of the electrical bits in British cars and motorcycles. Unfairly given a bad rap for the tendancy of cars neglected for many years to break down. See also "Have you checked the ground connection and the bullet connectors?"
MG	According to MG it doesn't stand for anything, but it originally meant Morris Garages
MOT	Ministry of Transportation - Yearly roadworthiness check all cars in the UK must go through
MOWOG	MOrris WOlesley mG (or Group or Garages depending who you talk to)
NOS	New Old Stock. It's 'old stock', but never been used. This is important for items which are no longer manufactured, or for which only poor quality reproductions are manufactured. For example, if you find a dusty 30 year old box with an unused Lucas switch in it, it's NOS.
Octane	The ability of gasoline (petrol) to resist detonation. Higher octane fuel burns slower than low octane fuel. Two systems mesure octane, MON and RON. Despite what some people think, there's no gain to be had by using a higher octane above whatever doesn't cause pinging in your engine.
OEM	Original Equipment Manufacturer. Correct parts made by the company that supplied the factory. Think of things like AP/Lockheed brake parts. Still made today to for our cars. In contrast, you have Borg & Beck clutches, which are OEM, and Quinton Hazel, which while they fit and work, are aftermarket parts.
Overrun	The period between taking your foot off the gas pedal and the engine RPMs dropping to idle
Oversteer	When the rear tires lose traction while cornering (fishtail)
PO	See DPO
Pinging	Technically, pre-ignition. Caused by hotspots igniting the air/fuel mixture before the spark, like the pointy bit in the head of early MGBs. Can be caused by too-advanced timing, low octane fuel, too high compression ratio. Less severe form of detonation. See also Knocking.
Pinking	Just another word for Pinging, I think its the UK version?
Prince of Darkness	See Lucas.
RBB	Rubber Bumper (post 1974½) MGB. See also CBB.
Rostyle	Rubery Owen mag-style wheels
Run-on	See dieseling
Smiths	Manufacturer of gauges that usually work, and sometimes show the correct value.
SU	Skinners Union. Carburettor manufacturer (early cars, and later cars with smart owners). Originally, carbs had leather parts, hence the connection to tanneries. MGBs have two SUs, each feeding two cylinders. May also stand for "Seldom Understood" - a wise man once said "90% of carb problems are electrical". See also Weber and ZS.
Tickover	Idle at lowest possible RPM, about 800 rpm, although some tuning manuals call for 600 rpm (good luck!)
Understeer	When the front tires lose traction while cornering (and you end up going straight instead)
Weber	Carburettor manufacturer popular with people who have too much money in their pocket and not enough books in their library.
WAG	Wild Assed Guess
YMMV	Your Mileage May Vary
ZS	Zenith-Stromberg carburettor manufacturer (later cars)

Where are the jack points on the MGB?

The original jack points are the little tubes below the doors on either side of the car. However I would NOT recommend using these, or the original jack, for a couple of reasons. One is the sills are often rusted out on MGBs and they might disintegrate under the presssure. The other reason is because it's not a great design and the jack could slip out, causing the car to fall. At best you've destroyed your door skin and paint job and at worst crushed your head while you're working on it. It's happened, unfortuately.

To lift the front of the car, put a trolley jack under the front crossmember (the huge beam bolted under the engine that the suspension is attached to). For extra safety, position the "cup" on the jack at the rear edge of the crossmembers, so that as the car lifts, the edge will tend to locate itself in the gaps in the cup. Then place jack stands under the frame rails (raised box sections under the car, behind the engine, which run parallel to the transmission tunnel). If you only need to raise one wheel, its safe to jack under the lower spring pans.

To lift the rear of the car, jack up under the axle differential housing (the big bulbous part in the middle of the axle), and place stands under either end of the axle beside the leaf springs (be careful not to squish the brake lines when you lower the car onto the stands).

ALWAYS use jack stands when working under the car. DO NOT rely on a jack, or cinderblocks, or anything else to hold the car up.

How do I tell what year a 'B is?

The easiest way is to compare the VIN plate on the top of the dash to the numbers below (for more accurate production data, check out Production Specs in the Library). At a glance, chrome bumper B's were made from 1963-1974 and rubbernose B's were made from 1974-1980 (in North America).

Where is the VIN?

The VIN for the early MGB, approximately 1962-69, may be found stamped on a plate that is secured to the inner right hand fender (looking from the rear of the car), located just in front of the radiator.

The VIN for the later MGB, approximately 1970-80, may be found stamped on a plate secured to the left hand door post, and on a plate secured to the top of the dashboard.

The VIN (Vehicle Identification Number) is also known as the Car Number or the Car ID.

What does the number on my dash/door post mean?: ex: GHN 5UC 54321

This information may not be applicable to VIN numbers for Mark IV (1980) MGBs.

1. Make	G	MG
2. Engine Type	H	cars between 1400cc and 2000cc
3. Body Type	N D	2 seated Roadster GT or Coupe
4. Series	3 4 5	Mk1 (1962-1967) Mk2 (1968-1969) Mk3 (1970-1979)
5. Market	U L R	USA (left-hand drive) Left-hand drive Right-hand drive
6. Model Year	none A B C D E F G H J L	1968-69 1969-70 1971 1972 1973 1974 1975 1976 1977 1978 1979
7+ Car Number	54321

What does the number on my engine mean?: ex: 18V/581F/L101

Bear with me, this is somewhat complex.

Group 1	18 G V	1798cc MG Vertical (in-line)
Group 2 (18G)	U R RC RWC	Center gear change Overdrive Automatic Center gear change w/ overdrive
Group 2 (18V)	581F 581Y 582F 582Y 583F 583Y 584Z 585Z 672Z 673Z 797AE 798AE 801AE 802AE 846F 847F Z AE	Bf+Pf+We Bf+Pf+We Bf+Pf+We+R Bf+Pf+We+R Bf+Pf+Rc Bf+Pf+Rc Re+Bf+Pf+We Re+Bf+Pf+We+R Re+Bf+Pf+Ck+We Re+Bf+Pf+Ck+We+R Re+Bf+Pf+Ck+Hl+We Re+Bf+Pf+Ck+Hl+We+R Re+Bf+Pf+Ck+Jl+We Re+Bf+Pf+Ck+Jl+We+R Bf+Pf+Tl+We Bf+Pf+Tl+We+R Carburetor crankcase ventilation, evaporative loss control and twin carburetors. Carburetor crankcase ventilation, air temperature control and evaporative loss control.
Group 2 (18V) Coding Symbols	Bf Ck Pf R Re We Hl Jl Tl	Lucas 16ACR or 17ACR alternator with negative earth Anti-run on valve Pre-engaged starter motor (when not normally fitted) Laycock overdrive Exhaust emission control Center gear change 1975 Federal regulation 1975 California regulation 1975 requirements
Group 3	H L L (2nd) 123	High compression Low compression Left hand drive Engine number

HoW CAN I BE DOWN?

Man, if you gotta ask...