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Classic Mini crankcase air breather kit mechanical fuel pump mounting

Classic Mini crankcase air breather kit mechanical fuel pump mounting

Classic Mini crankcase air breather kit mechanical fuel pump mounting
Part No: C-2A265
Fits the following:
Classic Mini
Sprite & MG Midget
Morris Minor
Crankcase Breather The A-Series engine has a reputation for leaking oil and/or smoking. One of the major causes of the various leaks is uncontrolled crankcase pressure. Remember that after the piston moves up in the block to create compression it also has to go back down in the block- this creates crankcase pressure. And if the piston rings are a little worn the ever present blowby can create considerable crankcase pressure. Mini Mania has developed an easy answer-an additional breather. This adapter block is designed to bolt onto the backside of any block that has a blanking plate where the mechanical fuel pump is sometimes located. The block provides baffled venting and has a 3/8-18 pipe thread output to allow you to create your own catch/vent system. Machined from billet aluminum and very trick looking!
As well as the adapter block, the kit contains:
2 * CAM6657 gaskets
2 * HC0518 bolts
2 * WL2051 lockwashers
Available only from Mini Mania!

Mini Mania Crankcase Ventilation Kit, C-2A265

Read all instructions thoroughly and check parts list before starting

This kit provides an internally baffled housing which enables the fuel pump port on the engine block to be used to vent the crankcase. The kit also includes fasteners and gaskets to mount the fitting but does not include a hose fitting and hose.

The fitting is tapped to accept a 3/8-18 NPT fitting. Fuel/emission hose of 5/8" ID is recommended and clear plastic tubing is readily available, but an equivalent size AN line can, of course be used. Whichever type of line is used, it is important that the line running between the fitting and its destination (air cleaner, catch tank, etc.) not form a loop or "sump" below the level of the fitting you've installed. If this happens, oil can accumulate in that loop and be blown out as liquid by crankcase pressure. As you might imagine, this could make a mess of things under the hood.

This kit may be used with any "A" series engine having an engine block with provision for a mechanical fuel pump.

We further recommend that some sort of "catch tank" be installed for the hose to drain to. This tank is need not be anything special, an old radiator overflow bottle or a second window washer bottle would be ideal. They are generally mounted on the firewall or some other appropriate location which allows it to be easily emptied. The tank should be vented so that no pressure buildup is possible.


Afix a 2A113 gasket to each face of the 3A0012 Vent Housing. The use of a contact-type sealer such as "Gaskecinch" (available through Mini Mania) is recommended.

Remove the fuel pump blanking plate and retain. Remove the two attaching studs from the block and remove old gasket and residue from both the blockand plate.

Position the plate over the face of the housing having a rectangular cutout and attach this combination to the block with the fasteners provided. Refer to the illustration.

Install your choice of hose fitting in the housing using (preferably) Teflon thread sealer, attach the hose and complete the plumbing.


Parts List for Breather Kit (C-2A265)

Item               Part No.               Description         Qty/kit

1. 3A0012    - Vent Housing                                           1                        
2. 12G3494  - Gasket, fuel pump                                   2                        
3. HC0518   - Bolt, 5/16-18 x 2.25" gr5                          2                        
4. WL2051   - Lockwasher, 5/16"                                    2

I have a 1973 classic mini 1275 engine with breathing issues that is causing significant oil leaking when pressure builds up in the crankcase. The engine has a breather in the rocker cover that is plumbed to both carb air filters. This is clearly insufficient and what I have read is that there is a clear need for additional breathing on this engine especially since it has been rebored slightly larger due to ring issues. I have purchased your fuel pump mounting breather kit and wonder firstly should I plumb this to one of the carb filters and restrict the rocker cover breathing to the other, or is there a better alternative to the breathing end. Also do you think these two breathing options will suffice? And if not can you suggest an alternate solution or an additional solution. The 1275 doesn't have the panels on the front of the engine and it has an older gearbox and clutch housing that does not have the breather port in it. (not to say it can't be changed?) Thanks for your help and I look forward to hearing from you.

 Not knowing anything about the history of the engine my first thoughts would be if the stock breathers were not sufficient, then the problems would be bad rings.  But saying that it could just be as simple as the previous owner mismatched parts that does not allow enough breathing.  In very stock system there needs to be a 'breather' in the valve cover and one in the engine.

As a 73 it would mean that a engine breather would have to be either in the timing cover or in the flywheel housing.  If neither of them are present then the breather designed for the stock fuel pump mounting will do the job.  The outlet for any of the breathers can simply be into a catch can of some sort to simply not dump onto the ground.  Should work either way.  
Give us a call if we can help further.

Mini Mania Tech Team
I'm trying to modify my old Datsun that lacks any pcv venting. I need to know the mounting bolt distance center to center if you be kind enough to. Your block looks to be a great design and stout. Your input would be much appreciated.
Mounting bolt distance is 1 3/4 spacing

Mini Mania Tech Team

The Classic Mini Parts and Accessories Experts

Building 1275 race motor for a midget. Assume this will work?
YES!  It will indeed work on some of the Midget blocks BUT be sure to check the exhaust side of the engine to be sure there is a plate covering the hole for the mechanical fuel pump. If not then you would have to drill a few holes. It sounds like you already know that crankcase breathing is very important in any of our motors but in a race car- it is critical for optimal performance.

Hope that helps.
Mini Mania Tech Team
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