Hit and miss engine

[Misterg]

I posted a photo of a little hit and miss engine that I made on the 'Mini Lathe' thread - thought some of you might like to see a few more:

I designed it from scratch and built it from bar stock on my 7 x 14 Chinese lathe as a distraction from the Covid 19 lock-down.

Stats:
Bore: 20.4 mm / 0.8"
Stroke: 26 mm / 1.02"
Displacement: 8.5 cc
Compression ratio was 4:1 (now 6:1)

The main structure is made from 50 x 38 x 6 extruded aluminium 'U' section and the cylinder block and head are made from 38 x 38 mm aluminium square bar. The cylinder liner and the crank are steel, and the piston is cast iron, sealed with a viton O-ring.

The flywheels are cast iron trolley jack wheels.

I anodised all of the aluminium parts using the process described by Mark Presling on Youtube.

The Hobby King ignition module had to be shaved down to fit under the engine bed. Batteries are let into the underside of the base.

It even runs!

(I'm using Coleman fuel with a few percent marine two stroke oil to try and keep the valves and top-end lubricated.)

VERY pleased with the way it has turned out!

Andy

 

[Coo]

Wow amazing !

 

[Barking Mat]

Thats beautiful.

 

[Migmac]

Very nice

 

[daleyd]

That’s fantastic Andy! Your talents were wasted working in the lab all those years

 

[gordon stephenson]

Very,very nice, first class design and manufacture,

 

[Shox Dr]

That is amazingly stable

 

[Misterg]

That’s fantastic Andy! Your talents were wasted working in the lab all those years

Yeah, I know !

 

[Dilkris]

I would describe this as nothing short of remarkable - fascinated with the valve gear (in singular); I am now off searching for how a "hit and miss" engine actually works ..... and I "was" going to go and cut the lawn.!!

 

[slim_boy_fat]

@Misterg Just stunning!! I know it's not the point, but any idea how many man hours went into it?

 

[Bullet2012]

Very nice, now you need to build something for it to power.
great work

 

[Parm]

Wonderfu. The genius of the membership never ceases to amaze me

 

[500e]

Superb

 

[Misterg]

Thank you!

I am now off searching for how a "hit and miss" engine actually works ..... and I "was" going to go and cut the lawn.!!

Pleased to save you from the lawn - a huge worm-hole of Youtube videos awaits!

They're just normal 4 stroke engines, but there's (often) no inlet cam, just an "atmospheric" inlet valve - the spring on the inlet valve is light enough that it opens under suction from the piston on the inlet stroke. The 'Hit and Miss' bit just refers to a crude governor mechanism that stops the engine over-speeding when off load. Commonly done (as in this case) by holding the exhaust valve open once the engine reaches a certain speed which will stop if firing ("missing"). Once the speed drops a little, the governor latch drops out and it can fire again (a "hit").

any idea how many man hours went into it?

I didn't keep a tally, but it was evenings and weekends from June to September for the building - maybe 20 hours a week? so 300 hours? A lot of stuff I was figuring out as I went along.

I spent longer in Fusion 360 playing with designs & doodling with it, but that's my alternative to crosswords, sudoku puzzles or TV.

 

[Kayos]

That is simply amazing

During lockdown i just got fat(ter)

 

[Dilkris]

You must have had more than a mini lathe to produce this masterpiece surely? Any pictures of your workshop/equipment? I just really enjoy looking at other people's set ups.

 

[pawsnizzy]

You can't ask for pictures of other peoples equipment surely! - this forum is changing

 

[Parm]

You can't ask for pictures of other peoples equipment surely! - this forum is changing

Yeah, sort of an unwritten rule

 

[Dilkris]

Ooops .....

 

[mtt.tr]

Bloody superb