Cam Follower Sleeve Removal.

The Lotus Twin Cam Cylinder Head.

At some point during the life of the Lotus Twin Cam engine, wear and tear within will require the cast iron cam follower sleeves to be removed and replaced with new sleeves. At first glance, the operation would appear to be a major project requiring special tools, and one that you might prefer to hand ball to a professional, to carry out the job a total strip to bare head status is required, but if you enjoy a mechanical challenge… keep reading.

At first glance, the job may appear to be beyond the home DIY mechanic/machinist, but taking a closer look, if proper tools are used, and care is taken, the job can be completed in the well equipped home workshop.

If you posses the required mechanical skills, have access to a lathe, and a selection of good tools, the removal of the cam follower sleeves is not that difficult to do without doing any damage to the cylinder head.

But I wonder how many “lotus enthusiasts and DIY mechanics have followed the instructions provided in the lotus factory workshop manual and ended up making one unholy mess of the surrounding cylinder head metal, and that’s what could happen if the following workshop manual directions are adopted.

Cam Follower Sleeves – To Remove.
2. Remove the cylinder head (Section ‘E.10’) and dismantle (Sections ‘E.12’).
3. Remove the cam follower sleeve by cutting a groove adjacent to each scallop, taking care that the cylinder head is not damaged. Using a suitable sharp chisel, remove the sleeve from its location, again taking care not to damage the cylinder head.

Now I don’t know what your hand tool skills are like, maybe you are an expert with an engineers hammer and a sharp cold chisel, but the chances of damaging the aluminium sleeve bore and the surrounding metal in some way when attempting to remove the sleeve in the manner described above is extremely high, I can tell you from personal experience, the sleeves can be buggers of things to remove using the above method with out doing any damage to the cylinder head sleeve bore or surrounding metal.

There is however a far easier way to remove the cam follower sleeves with zero damage to the sleeve bore and surrounding metal, in the following article and videos, we’ll show you how.

We’ll attempt to explain how the job can be achieved in the home workshop.

You may have heard of the myth about the mechanic who could carry out a complete engine rebuild with a few spanners, two screwdrivers and a nail file, those days have long gone, (If they really ever existed) and today there are many mechanical minded elan enthusiasts who have workshops equipped with high quality tools and machines that only a couple of decades ago you would only expect to find in some professional work shops.

The Ford Lotus twin cam is an engine that continues to live on well beyond what most people ever believed it would, but the longevity is understandable because it is such an amazingly robust engine. How many modern engines do you know of that can produce that beautiful aural sound that only a Weber breathing twin cam engine can provide?

OK, it does sound very nice, but lets not get to carried away.

Tools and machines you required for this operation, not to mention the mechanical skills and common sense approach.

• Lathe – for machining special bits and pieces for tools and jigs.
• Variable speed electric die grinder – variable speed for cutting different types of metals.
• Carbide burrs (Cutters) to cut slits in the cast iron follower sleeves to relieve the shrink fit pressure.
• Special puller – DIY made to suit. (Explained via video later in article).
• Oxy Acet for bronze welding metal sleeve puller parts together.
• Plus the usual spanners and other tools.

The cast iron cam follower sleeves consist of a basic machined shape, essentially a small barrel shape with a locating flange at the top. The sleeve OD is machined or ground to a specific over size in order to create the holding crush when the iron parts are frozen in liquid nitrogen then quickly installed into a warm (150C deg) cylinder head, and allowed to normalise, creating a strong shrink fit, the sleeves are then bored/honed to correct clearance ID to accept the new cam followers.

The original cam follower sleeve material is made of cast iron which is durable and hard wearing, but other materials such as a special bronze could also be ideal for machining cam follower sleeves, we are undecided as to which material will be used, but will probably stay with the original cast iron sleeve approach.

In order to remove the sleeves, the shrink/press fit tolerance is required to be collapsed, and to do that a groove is cut vertically from top to bottom of the follower, one the best tools for doing this by hand is to use a variable speed electric die grinder (Makita GDO800C Variable speed-5000 to 25000RPM) fitted with a 5/16″Dia carbide ball end burr .

This operation requires a steady hand and careful work with the die grinder, a milling machine would be a better option, but the job can be easily achieved by hand as we will illustrate.
We recorded some videos to illustrate the process, we hope you learn something from this DIY article.
Video 1: Preparing To Remove The Follower Sleeve.

These videos were recorded some time ago on an old style Nokia mobile phone, the quality is just OK, they have not been edited or enhanced in any way, what you see is what you get, warts and all.
Video 2: Cutting The Relieving Slot In The Follower.

The variable speed Makita electric die grinder is a great tool to have in the workshop, many uses can be found for it, carbide burrs can be purchased in many different shapes and sizes.
Video 3: The Final Cutting Of The Sleeve.

The die grinder is an ideal tool to cut a thin groove down the inside of the follower sleeve, as long as care is taken and frequent inspections are made, the job will be completed with out any problems.

Video 4: The Cam Follower Extraction Tool.

The sleeve extraction tool is constructed from mild steel, there is no need to resort to 4140, the pressures are not all that great. Once the sleeves have been extracted the tool may not be used again for a very long time.

Video 5: Extraction Of The Sleeve From The Cylinder Head.

When the extractor tool is set up, pressure is applied via the threaded rod, a light click or snap will be heard when the sleeve releases, then it will slide out with ease.

So that’s it, the above procedure is repeated another seven times and all of the eight sleeves will be removed without doing any damage to the cylinder head. All that is required then is to take the head and new follower sleeves to someone who has an oven to reheat the head and a facility to freeze the new sleeves just before they are refitted, and the cylinder head and assembly is allowed to normalise. After the new sleeves are fitted, the cam lobe side clearance recesses will need to be milled, and also the boring of the cast iron follower sleeve ID to the correct clearance for the new steel buckets or followers, and when the complete project is completed and reassembled, the valve train components should last for many more decades.

You might be up to an even bigger challenge and machine a set of cast iron follower sleeves from bearing quality cast iron bar stock, it can be done if you own a lathe and understand the turning skills required to do the job, but that’s a story for another day.