'Full-flow' oil pipe adapter 1H922 as pictured by a number of suppliers. Note this type stands the cooler hose thread away from the block by about an inch: (Motaclan/Leacy)
Adapter 1H922 (arrowed) screwed into the block with the spigot projecting into the oil pump gallery (10), isolating it from the main bearing and oil gauge gallery (12) ensuring the oil flows through the filter and cooler (where fitted) before it reaches the bearings:
An alternative adapter pictured by NTG for the MGA (and others) and found when Googling 1H922, although NTG list it as 'B034'. This one has the cooler thread close to the block. Also the identical photograph is shown on another NTG page found by Googling 1H1291, but unlike 1H922 that part number is not referenced anywhere else: (NTG Motor Services)
The 'stand-off' type allows a spanner (and maybe a socket) to be used on the adapter without fouling the back-plate nut that is close by, or the oil gauge adapter (it's amazing how oily an engine seems to get even when it doesn't drip ...):
The drawing in Parts Catalogue shows the same shape as the NTG item, and with the 1H922 part number. However drawings are only representative and are often carried forward from a previous version without being redrawn even though the part number has changed: (Parts Catalogue)
Parts catalogue drawing of direct pipe 1H1056 showing a separate ferrule of 'olive' that could be soldered further back from the end of the pipe to leave a spigot that would project into the rear gallery to largely seal that off from the main-bearing gallery. This would need plain adapter AHH6701, although a 'full flow' adapter is shown with it:
'Direct' pipe 1H1056 with the fitting right on the end of the pipe, requiring a 'full flow' adapter: (NTG Motor Services)
'Direct' pipe 12H4259 ditto: (MGE)
'Direct' pipe 1H1056 with adapter 1H922 attached: (MGE)
'Plain' adapter AHH6701, used at the filter adapter for the return hose from the cooler. However Motaclan/Leacy show a quantity of 2 which is incorrect, if this is used in the block with a cooler hose then the majority of the oil will bypass the filter:
The picture on the left could be showing a stand-off 'full flow' adapter, the one on the right does not seem to be a 'full flow' adapter of either type. Both pipe unions appear to screw into the adapter, rather than on to it which would be the case with either of the 'full flow' adapters pictured above. Unless there is a spigot projecting into the oil pump gallery the majority of the oil will bypass the filter. The left image is of a 'homebrew' fitting of a spin-on filter adapter to an MGA from Barney Gaylord's pages. The right image is from Willy Revit in Tasmania and is said to be of an engine from a UK 1976, in which case someone has removed the oil cooler fitting (according to Clausager all five-bearing MGB engines had the cooler) and substituted a direct pipe using an unknown adapter:
