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I have used a 2 pack pourable material (as opposed to putty): https://www.mbfg.co.uk/pt-flex-20-rubber.html?gad_source=1&gclid=Cj0KCQjwudexBhDKARIsAI-GWYV5Gai-7aE1RvyYSm8nZqLsgs1PhOJpUq-eoh0vr9qdm_XVOvzo1_AaAptIEALw_wcB

I've just built the Whittle V8 from Hemingway. I should note that the kit doesn't quite contain all the materials needed, nor does it include screws or nuts, most of which are non-standard and will need to be made from scratch or modified from available parts. It is most definitely not a...

Ideally, a balance shaft would be concentric with the crankshaft, so that it does not generate a secondary vibration due to the offset between centres of rotation. If we consider the counterweights on a normal crankshaft viewer from the end, they move both up and down (opposing the mass of the...

The electrical analogy is great as far as it goes, but it has it's limits. Electricity has no effective mass, so it doesn't exhibit the square law change in kinetic energy with velocity which is seem in fluids and is fundamental to Bernoulli's principles.

Another reason why model engines don't usually have float chambers is the relatively small changes in fuel height in the tank. In a typical model aircraft, the fuel tank is mounted within a few inches of the carburettor. With the model facing directly upward, the pressure difference required to...

I have had to change idle jets to work with modern fuels with alcohol. My wife has a 2000 Triumph 790 Bonneville. It is set up from the manufacturer as a 'lean burn' engine and needs the choke on for some time even in warm weather. Simply adjusting the idle mixture screw could achieve a good...

Hi Patrick, the TIG weld was with no filler, just fusion. I don't remember the current, but probably less than 50A (My pins are 5mm diameter). My twin has a two piece crankcase, in fact, each half is both crankcase and cylinder and the halves are identical. It is possible to fit an assembled...

When I made the crankshaft for my opposed twin, I machined the main journals (slightly oversize) and webs in one piece, with the webs connected by a continuation of the main journals between them. I then bored the webs for the big end journals, which are hard dowel pins. The pins were then...

The term stainless steel covers a multitude of alloys with range of chrome and nickel content. As stated previously, grades such as 303 and 304 are unlikely to be suitable for use with metal piston rings, as the surface will gall. Grades such as 17-4 may be more suitable. I have used 17-4 in...

It didn't take long for this thread to arrive at an office topic confrontation...

All good advice above, but most of all, feel free to ask questions! There is a wealth of experience among the members of this group and that should be your most useful resource as you build your first engines. What do you have access to in the way of machine tools and measuring insruments?

I had assumed that the term 'undercut' was being used to describe the gap between the teeth. Certainly, if one is considering the tooth form, it could be described as 'undercut', but then a square spline is similarly 'undercut'. I can see how this may have lead Nikhil to question whether the...

Am I missing something? I don't see how it would be possible to generate an undercut in a single pass with a rotating cutter. If the tips of the cutter were shaped to form the undercut, they would remove material from the flanks of the gear, leaving no undercut and an incorrect form. I can see...

I make copper gaskets from domestic plumbing pipe. Cut the required length, slit along the length with a hacksaw, flatten out and re-anneal.

Certainly the combustion in the cylinders is the source of the excitation, but I do not agree that the firing order is the primary source of gross engine vibration, which is what most of us will first think of when discussuing engine vibration. I have owned a number of Triumph twin cylinder...

When aligning the cylinder faces to the crankshaft, most important is that the faces are parallel to the crank axis. Small errors in the position of the cylinder bores, both along and across the crank axis will not be a problem in terms of the piston / rod / crankshaft geometry. Nice work - I do...

The twin crank engine described could be very well balanced. The pistons rise and fall together, but the cranks rotate in opposite directions, so the pistons and rods could be fully balanced by counterweights, while the secondary vibrations of the counterweights would balance one another. The...

With enough levers, it is possible to control any number of valves with a single cam lobe. Using a single cam for both inlet and exhaust does limit the design to equal inlet and exhaust duration.

Hi Bob, look in the files section, among others, there is a sub section titled errata. Cheers, Pete.

When designing a part in 3D cad, I try to approach it in the same way that it will be machined. I start by modelling the billet, then add features in the same way that they will be machined, e.g. a main bore relative to an end face, concentric features, fixing holes and finally non critical...