Twin Cam Head To Block Adjustable Breather-Oil-Drainer Tube.

Twin Cam Cylinder Head To Block Adjustable Oil Drainer Breather Tube.
If there is one annoying thing with the twin cam engine, it would have to be the rubber drainer that plugs into a hole under the protruding or overhang part of the alloy twin cam head, and the bottom locates into the lower breather hole in the cylinder block. While the idea works well while the rubber drainer is new, it does not seem to take all that long before the rubber perishes and splits, and that’s when you notice a large oil slick eliminating from under the engine.

This is not a good look, and more than likely will also lead to a failed road worthy test…. Oil dripping from engines onto road surfaces seems to be frowned upon these days, where it was tolerated a couple of decades back… times and attitudes have changed.

So what to do about the oil drainer, most people pull the old one out and replace with a new item, and forget about it until the drainer gives trouble again, which, depending on how often the car is used, could be a considerable length of time, or it may not, it really depends on the quality of the rubber drainer or breather tube.

In this article, we will give an overview about how the twin cam enthusiast could manufacture (If you have the where with all) an adjustable metal drainer that is sealed with “O” rings top and bottom, as well as internally.

From this point on, there are workshop skills involved, an understanding of how to operate a lathe, plus also understand how to do silver solder or silver brazing… call it what you will.

This project will also mean that you will have the engine out of the car,  and or,  it is undergoing a full rebuild,  the reason being, that there is a small amount of machining (End Milling) to carry out on the block to make this gadget work. The breather parts are machined out of mild steel round stock, readily available at steel merchants. Again we are not delving into detailed instructions on the building/machining process, we did not use any CAD design software, and if you are switched on, you should not have to either.

The oil drain tube, being height adjustable can be installed and removed with the cylinder head in situ, the top and bottom O rings create the seal, assisted by the smaller internal O rings. The oil drainer illustrated in this project has not shown any signs of oil leaks or weeping, and it should not leak, because of the way the drainer has been designed.

To construct, measure the upper hole in the cyl head, as well as the hole in the block, also measure the distance between the head surface and block surface where the O rings create the seal. The small bosses that protrude into the holes can be a loose fit, which will help during installation.

From the many projects that were recorded during the engine rebuild, we actually omitted to take any measurements of the various parts of the drainer, so lets just show the upper cyl head hole first.

There are two ways to go about creating the flat surface which is required for the O ring to do it’s job, we mentioned above that the “flat” face should be machined in the milling machine with a suitable sized end mill cutter, that method will ensure an accurate and perfectly flat surface, however if you look closely at the image above you will notice that this flat surface has not been milled, in fact it was done with a 4″ angle grinder fitted with a brand new grinding wheel, but before you embark down that route be very careful.

It is quite difficult to attain a flat surface as accurate and square as would be achieved with a milling cutter, a grinding disc will create a shower of ground cast iron dust and abrasive particles, which must be kept out of the engine at all costs, so the openings and holes have to blocked with compacted rags to keep the grindings out of the engine, and care must be taken to make sure the cut is square to the hole, it can be done, but it is difficult to be dead accurate.

As with all custom machined parts, there are no fixed measurements to go by, this project was virtually created on the fly, and was changed and modified as the project progressed,  you do need advanced lathe skills, and be familiar with turning and boring as well as thread cutting on the lathe, another option is to farm it out, but it will cost more than it’s worth to do that, all of the projects on this blog are idea generators for the lotus elan enthusiast, useful things that can be produced in the home workshop for your lotus elan.

This shot shows the assembly order of the various parts, the large O ring is placed over the metal plug with threaded body on the left goes to the top into the cyl head hole, the short nut with the body and O ring is then threaded on, the lower body part does not have any internal thread, but the internal bores are machined so that the smaller O rings provide an internal seal, the tension on the top and bottom O rings is controlled by how tight the small nut in the middle is tightened. DO NOT over tighten.

A closer view of the various parts of the drainer installed.

The drainer installed between the cylinder head and the engine block, only a slight amount of compression is required for the O rings to do their job. This might look and sound like a lot of trouble to make, but the thing is, it really works, looks very neat, and the O rings will last for many years.

The end result is NO MORE OIL LEAKS.

Is this project for you? Only you will be able to answer that, Yes, it’s different to what is considered normal on a twin cam, and I would not be surprised if some one pinches the design and begins to make and sell them, well good luck I say.