Roy's Little Engine

[Jo]

That is a nice looking rocker arm Mike and the use of the flat overcomes any sideways movement 


Question for you Graham... I am trying to work out how long the catch arm needs to be to hold the exhaust valve out sufficiently to work: Is it just slightly off its seat or should it catch at the full extent 


And how big should the gap be above the valve when the rod is resting 

Jo

[michaelr]

Jo,Thanks for your comment on my rocker arm, it's simple but it does the job. the RLE was my first IC engine build.


Mike.

[Gas_mantle]

The more I see of these engines the more interested I become :-)  Is ordinary petrol the intended fuel or are they meant to be run on Coleman type fuels ?

As the risk of asking a daft question how long can they run on say a gallon of petrol ?

[Jasonb]

They will run fine on pump petrol but quite a few of us prefer Colmans as it does not smell anywhere near as much as petrol, Aspen is another similar fuel that they will run on.

You would get a couple of days running from a gallon of fuel.

Jo I usually have the latch hold the exhaust about 3/4 open and just a hint of light showing between rocker and valve. You can't latch them fully open as the rod needs to slide part way back to engage on the latch.

[Alyn Foundry]

Sorry All.

I was out in the workshop with Nattie.

Jo.

As Jason has already stated the valve tappet clearance 6 to 8 Thousands of an inch. I like to see about 3/4 of the full travel for the latch position. This ensures both a good " freewheeling " action and an unlatch when the next cycle commences. The more open you can keep the exhaust valve the less likelihood of pulling a mixture through the atmospheric inlet.

Peter.

Yes the R.L.E. was meant to run on Petrol or Propane and a Gallon of petrol would probably get so " stale " you wouldn't get to finish it!

Before I converted mine to be a " Dragsaw " the old 1 Ounce tobacco tin tank could do almost a day on the rally field.

Cheers Graham.

[Gas_mantle]

Thanks. I've never seen one suddenly put under load, do they eventually fire at every revolution if the load is high ?

[Alyn Foundry]

Hi Peter.

Let's look at this the other way around.

We've all become used to running our " hit and miss " engines on the governor. However, the governors were only there to prevent " overspeeding " if the load should suddenly disappear, like a belt snapping or coming off the drive pulley. We set the control springs light so that they just run above idle speed.

This form of governor shouldn't be confused with other types that control the speed via quantative means,
" throttle governed " where the air volume is varied to suit the load condition.

Cheers Graham.

[Jo]

I decided to steal Mike's solution for the slight sideways movement on the rocker arm and flattened off the end of the tappet adjuster 

I needed a couple of 1.6mm diameter pins about 14mm long for the governor latch so Mr Silky turned these down in one from 3mm Stainless for me  One of these pins was for the spring on the latch and the other is the pivot pin for the arm. Checking the movement: sufficient clearance and governor holds and trips off as required 

Jo

[Alyn Foundry]

Hi Jo.

Very nice workmanship, lovely.   

How does the exhaust valve timing look? For these engines the only real concern is that it closes at, or slightly before TDC.

The commencement of the exhaust cycle can start anywhere from, in clock speak, 20 past the hour, but 25 to 27 minutes is better.

Cheers Graham.

[tangler]

Nice work Jo ( as usual ).

I always  liked the RLE.  Sadly, by the time I got round to getting a kit they were no longer available  .  Not the least of it's attractions is the fact that it's cast iron rather than the ally of most of the alternatives.  Great to have Graham's comments as well.

Looking forward to the video 

Rod

[Jo]

Thanks Graham and Rod 

No idea on the timing Graham. I wouldn't know what to look for  The crank gear is not yet pinned.

Rod the video is a long way off here is still lots of bits to make on this engine and unknown challenges to overcome  . I know I am on holiday this week but not all the time will be spent in the workshop but I note that the rain Gods are planning on encouraging my workshop time.


I fancy doing a bit more of the governor bits today but the sun is out and the garden is looking nice   

Jo

[Bluechip]

I fancy doing a bit more of the governor bits today but the sun is out and the garden is looking nice   

Jo

Rather intrigued by this governor mechanism, you'll have to give me a demo when I come down .. 

Get yourself out into the garden while the weather is OK. You can indulge in casting bothering any time ... 

Just filled your firewood bag ...     

Dave

[Alyn Foundry]

Thanks Graham and Rod 

No idea on the timing Graham. I wouldn't know what to look for  The crank gear is not yet pinned.

Jo

Good morning Jo.

Then please, let me enlighten you.

Mark a tooth on the crank pinion and slide it back onto the crankshaft. Remove your spark plug. Set your halftime pinion so that the cam is just touching the follower. Proceed to rotate the crank pinion and watch the valve first open then close again. If things are perfect, you would see that the crank pinion had rotated 180 degrees for this cycle.

As it's highly unlikely to be perfect the first time you will have to compromise a little. If the operation is accomplished in less than 180 degrees of crank rotation you still need to set exhaust fully closed at TDC.
Usually the case is more than 180 degrees so the exhaust still must close at TDC but can commence to open before BDC.

Once you're happy with the timing, mark the pinion and crankshaft for subsequent pinning.

I hope this helps, but please don't hesitate to ask further questions if necessary.

Cheers Graham.

[Jasonb]

While talking exhaust timing should the cam lift be reduced when using the longer rocker arm as the valve end will move more than it did when the exhaust valve was closer to the pivot point.

[Alyn Foundry]

Hi Jason.

Well....

If we were talking " high performance " then yes the extra lift would see catastrophic damage to both valve and piston. However....

With an approximate 1/2" of clearance between piston and cylinder head or even 1/4" with the higher compression alternative there's little chance of a collision.

Cheers Graham.