I often have problems with small sealing washers falling out of their designated baggies and becoming lost or loose and unidentifiable. There are also occasions when I need a seal washer I don't have in hand, and it is a royal PITA to have to place a parts order and wait (especially when minimum shipping charge is more than the cost of the part). So I have compiled this list of every copper and fiber sealing washer used in the MGA (and common to some other cars as well). It is listed first in order of sizes, ID x OD x Thickness so you identify a loose part with corresponding part numbers and where it is used. It should also help to find a part at a local hardware or auto parts store. Immediately following is a spread sheet copy (click to download) that you can sort in order of part numbers (or any other way you like) .

IDxODxThickness	BMC No.	Moss No.	Name	Where Used
0.310x0.560x0.060	2K4958	324-610	Washer, fiber 5/16 ID	tappet cover (2), gearbox side cover (1), water pump
0.380x0.685x0.016	AUC2122	370-250	Washer, copper	upper jet bearing, see Carburetorsp
0.393x0.590x0.045	3H2287	324-730	Washer, copper	Master cylinder clutch adapter bottom, brake hose front (1500) and rear (all), rear brake banjo bottom
0.440x0.680x0.057	3H549	324-720	Washer, copper, (alt 7H7456)	Master cylinder clutch banjo bottom, clutch slave banjo bottom, clutch slave hose, rear brake banjo top -part no. change; was 7H7456
0.440x0.680x0.057	7H7456	324-720	Washer, copper, (alt 3H549)	Master cylinder clutch banjo bottom, clutch slave banjo bottom, clutch slave hose, rear brake banjo top -part no. changed to 3H549
0.440x0.870x0.063	AUC1384	372-180	Washer. fiber 7/16 ID	MGA 1600 banjo stud to throttle body, see Carburetors
0.500x0.630x0.060	AUC1928	370-160	Washer, fiber, C63, internal teeth	carb float cover vent banjo bottom, see Carburetors
0.515x0.688x0.070	6K638	324-626	Washer, copper, 13mm ID	engine transverse oil hole plug, oil gauge union, oil drain plug (1/4-BSPP thread, 13mm, 19-TPI)
?	300398	324-660	Washer, copper (crush)	water union 1500 heater return -Moss UK 232043A
?	AAA4657	324-660	Washer, copper (crush)	water union 1600 heater return -Moss UK 232043A
?	BHA4088	?	Washer, aluminum	heater return pipes -Twin Cam (2)
0.520x0.775x0.090	AUA1405	375-025	Washer, fiber	fuel pump inlet to body, fiber washer
0.530x0.750x0.060	2K4954	324-671	Washer, fiber, red ¼ BSP	water drain taps, engine and raditor – alt 2K4975
0.530x0.750x0.060	2K4975	324-671	Washer, fiber, red ¼ BSP	water drain taps, engine and raditor – alt 2K4954
0.532x0.738x0.055	3H550	324-740	Washer, copper, 0.532 ID	master cylinder clutch banjo top, clutch slave banjo top,
0.560x0.653x0.020	AUC3233	370-410	Washer, copper	lower jet bearing ,see Carburetors
0.560x0.800x0.050	???	???	Washer, fiber	SU fuel pump filter bottom plug
0.590x0.816x0.070	AUA1442	375-035	Washer, fiber	fuel pump outlet union to body,fiber washer (could be copper crush washer from Moss)
0.600x0.800x0.070	AUA1479	375-035	Washer -cage (fiber,thin)	fuel pump outlet, fiber washer, (could be copper crush washer)
0.640x0.860x0.074	AED172	324-805	Washer, copper (5/8" nom. ID)	Temperature, gauge adapter, 1275 engine 1968-'74 Spridget cars with cross-flow radiator
0.660x0.890x0.075	6K431	324-???	Washer, copper (16.5mm nom. ID)	oil drain plug -Twin Cam (3/8-BSPP thread, 16.3mm, 19-TPI)
0.699x0.890x0.060	AUC2141	370-650	Washer, fiber 11/16 ID	float cover banjo bolt, see Carburetors
0.699x0.890x0.060	AUC4900	370-650	Washer, fiber 11/16 ID	caruretor damper, see Carburetors
0.820x1.120x0.030	2K4982	324-650	Washer, fiber 13/16 ID	oil pressure relief valve cap (2)
0.825x1.040x0.075	6K501	324-800	Washer, copper	crush washer, engine oil unions, external oil pipe and oil cooler
0.825x1.040x0.075	ARH1112	324-800	Washer, copper (crush)	crush washer -not available use AHH6701 (adapter with bonded seal)
---	ARH1113	435-590	Adapter union (separate)	engine external oil pipe and oil cooler
---	AHH6701	N/A	Adapter union (assembly)	union and bonded seal, replaces ARH1112 seal and ARH1113 adapter
1.025x1.250x0.055	88G208	324-820	Washer, copper, thin, 1.045 ID	speedo drive on gearbox -88G208 part no changed to 51K3169
1.025x1.250x0.055	51K3169	324-820	Washer, copper, thin, 1.045 ID	speedo drive on gearbox -part no changed, was 88G208
0.218x0.625x.062		37-1994	Washer, Stat-O-Seal 1/ 4	WSAE0.25
0.344x0.687x.062		37-1995	Washer, Stat-O-Seal 5/16	WSAE0.31
0.406x0.812x.062		37-2000	Washer, Stat-O-Seal 3/8	WSAE0.37
0.469x0.922x.062			Washer, Stat-O-Seal 7/16	WSAE0.43
0.531x1.062x.080		37-1999	Washer, Stat-O-Seal 1/2	WSAE0.50

Click for sortable Spreadsheet copy


Tech Tip: To anneal a work hardened copper washer, heat to red hot and dip it immediately in cold water.
https://www.youtube.com/watch?v=DOnLwjfHmIc