Easy Piston Pin & Ring Installation.

When the time arrives to build a brand new engine, one cant be too careful about the way that the engine components are handled.

Parts such as delicate aluminium pistons can be very easily scored and marked, so they require careful handling. The best thing that be done in careful handling is to make some special soft jaws or holding fixtures.

The difficult operation for the DIY mechanic will be the holding of each piston while installing the compression and oil rings, and the con-rod pin.

The first thought might be to wrap the piston in soft material and clamp it in the vice, this might work, if you are really careful, but the chances of damage to the piston skirt and the rings is pretty high… and you don’t want that to happen, do you?

In this article, we illustrate two, cheap to make timber clamps, the first, is designed to clamp onto the piston crown securely, so that the the pin can be easily installed. The pin in the twin cam piston is generally a firm hand push fit, the specially made split timber clamp will grip the piston firmly when it is held in an engineers bench vice without damaging or scoring any part of the piston.

Having made and employed the clamps during the rebuild of the 1700cc twin cam, I can highly recommend that any DIY engine builder spend the short amount of time required to make these very useful workshop tools.

The piston clamp is made from soft Oregon timber, (Pine would be OK also) the short pieces of timber were actually cut from some wall studs that were removed during a small house reno we did, (I knew they would come in handy for something,) the Oregon timber is ideal for the purpose.
Measurements of each clamp half: 5″ x 2 1/4″ x 1 1/4″.

As it is easy to see, the clamp wraps and holds the piston securely, enabling the piston pin to be inserted along with the con-rod. The timber clamping or holding tool makes the job really simple to do, and there’s no possibility of the piston being marked or scored in any way.

Note; that the crown of the piston is smaller in diameter than the lower skirt area, so you really need to make up two clamps for the job, they are simple to make in the lathe, and they don’t take much effort. But will make your job so much easier.

After the piston pin has been inserted, the clamp can be loosened and tightened (Undo the vice) so that piston can be rotated and the circlips (Seager clips) installed into the internal grooves of the pin bore to securely locate the piston pin.

The second timber clamp we will show you is made to clamp the piston skirt, again, this clamp is mounted in the bench vice, the piston is held securely, and now the delicate operation of installing the oil rings and compression rings can be undertaken.

With the piston securely clamped, and after the rings have been gapped, (010″) they are easy to install onto the piston, making the piston and con rod assemblies ready to install into the engine block.

There is one other feature of this piston holding fixture that I will show you in the photo below.

Because of the split style of holding clamp, you may have noticed the hole bored through the centre, allowing the con-rod assembly to drop below the piston, another neat feature of the two-part holding block.

Special tools like these do take time to make, you will either see the value in them or you wont, if you take care with your work and you want the very best and professional DIY results, then it will be worth the effort to take the time out to make any special tool and or holding fixture that will bring you closer to achieving outstanding success with your engine build project.

The most important thing is that it will greatly reduce the risk and chance that an accident will happen and something will be damaged.