Mastiff lc mason engine REDO .

[minh-thanh]

Hi David .
Just ask to know more :
Yes, I agree, with model engines it doesn't matter much
But is it the true purpose of a Boxer engine to create balance? That firing order doesn't fit the Boxer engine's purpose, right?

 

[deltatango]

Hi David .
Just ask to know more :
Yes, I agree, with model engines it doesn't matter much
But is it the true purpose of a Boxer engine to create balance? That firing order doesn't fit the Boxer engine's purpose, right?

Hi Minh,
I think that the excellent dynamic balance of a flat 4 engine comes from the forces due to reciprocating masses on opposite sides of the crankshaft cancelling each other out. When a piston on one side of the crank is changing direction (e.g. around the top of its stroke) there is another one on the other side doing the same thing in the opposite direction, so the forces cancel. I'm not sure how the size of the impulse from firing compares with the force due to the reciprocating masses but I suspect it is much smaller. Maybe someone else on the forum has done the arithmetic and can tell us?

The Subaru motors I have known are red lined at 6500 RPM and in 1st gear they go past that frightenly quickly when you put your foot down. They use the same firing order as Len Mason did with Mastiff. If it's good enough for Subaru, then it probably should be good enough for the rest of us

The other flat 4 engine I've owned (a long time ago now) was in a Citroen GS and the firing order for that is given as: 1 (rear left cylinder), 4 (front right), 3 (rear right), 2 (front left) using the cylinder numbers from the manual. In Mastiff numbering this translates to 3 1 2 4 which matches Mastiff.

You've done a great job with the pistons! In my version I just lapped the pistons to their liners, and the fit is very good, but it is still some oil getting past the pistons.

BTW the Citroen motor allowed oil to get past the piston when it was turned off and (even when new) there was a puff of oil smoke when it was first started in the morning. Subarus don't suffer from this.

I really hope I'm getting all this correct, if I've got something wrong then there are plenty of forum members who can correct me!

Regards, David

 

[minh-thanh]

Hi Minh,
I think that the excellent dynamic balance of a flat 4 engine comes from the forces due to reciprocating masses on opposite sides of the crankshaft cancelling each other out. When a piston on one side of the crank is changing direction (e.g. around the top of its stroke) there is another one on the other side doing the same thing in the opposite direction, so the forces cancel. I'm not sure how the size of the impulse from firing compares with the force due to the reciprocating masses but I suspect it is much smaller. Maybe someone else on the forum has done the arithmetic and can tell us?

The Subaru motors I have known are red lined at 6500 RPM and in 1st gear they go past that frightenly quickly when you put your foot down. They use the same firing order as Len Mason did with Mastiff. If it's good enough for Subaru, then it probably should be good enough for the rest of us

The other flat 4 engine I've owned (a long time ago now) was in a Citroen GS and the firing order for that is given as: 1 (rear left cylinder), 4 (front right), 3 (rear right), 2 (front left) using the cylinder numbers from the manual. In Mastiff numbering this translates to 3 1 2 4 which matches Mastiff.

You've done a great job with the pistons! In my version I just lapped the pistons to their liners, and the fit is very good, but it is still some oil getting past the pistons.

BTW the Citroen motor allowed oil to get past the piston when it was turned off and (even when new) there was a puff of oil smoke when it was first started in the morning. Subarus don't suffer from this.

I really hope I'm getting all this correct, if I've got something wrong then there are plenty of forum members who can correct me!

Regards, David

I searched for information on the internet, it's true to what you said, and the way I did the firing order was wrong. That helps me a lot, avoid mistakes...because I make the camshaft from one piece., Crazy when make new the camshaft
Thank you
About the piston and oil rings : it's new to me - I'm not sure I get the desired results, although I did a simple test with it: it's quite good. But it was quite fun to make them and there are a few things I learned from it

 

[Jens Eirik Skogstad]

Minh Thanh..

The firing order 1-2-4-3 is correct in the Mastiff engine.

To example VW Beetle engine firing order 1-4-3-2 and Subaru boxer engine 1-3-2-4.

All engines has same crankshaft with same piston movement.

Location of cylinder number and firing order:

Mastiff engine 1-2-4-3

2------3
1------4

VW Beetle engine 1-4-3-2

3------1
4------2

Subaru boxer engine 1-3-2-4

2------1
4------3

Common to all engines, they receive a distributed power impulse from combustion and balanced running.

 

[minh-thanh]

Hi All .
An update
The tool bar 4mm order arrived today , and I have a little time so I cut it to size
Time to clean all again...and put it back together

 

[minh-thanh]

A little update
I have assembled a few parts, everything goes according to plan, I was going to assemble the valves but I forgot I haven't prepared the springs yet.
Another news, I won't be visiting the forum very often, maybe a week or more. , That helps me focus...
I will visit the forum when I have something really new

 

[minh-thanh]

Hi All .
The valves have been assembled, and they have been tested for leaks with diesel oil : results were ok.

I made an excel spreadsheet with the lobe angles (I have made several excel spreadsheets for several engines and I plan to combine them), although I have checked several times, the angles match Together it confuses me.

So I took a simulated camshaft and adjusted the lobes according to the spreadsheet data, and the results were correct.

And proceed to make the camshaft, and the result :

 

[minh-thanh]

Hi All .
An update :
Now, the camshaft is done .
Everything has been assembled, preliminarily checked: everything according to plan.
Next will be the cylinder head, making the gears.

 

[minh-thanh]

One part of the engine that I hate the most is the carburetor
I plan to follow the plan and will add a one-way valve and a fuel float to it - That would make it just like the old standard carburetor. , That gives a lot of advantages over carburetors that I have ever made and seen

Hope everything will be okay .

 

[minh-thanh]

Hi All !
I tried making floats. aluminum, and check its buoyancy, it's quite okay
It will be made even thinner, as thin and light as possible

 

[minh-thanh]

I shortened the float and finished it up a bit for testing
Maybe it will need reduce the weight by another 15, 20%.

 

[Sprocket]

Are you testing it in the fuel you will use? Might float differently than it you test in water. Just a thought.
Doug

 

[minh-thanh]

Might float differently than it you test in water.
Doug

Exactly .
Thank you .
I just tested it in water to see what I could do

 

[Jens Eirik Skogstad]

Petrol has low density than water then the aluminium float will be lower than in water. Cork as float works better due low weight. Use thinn steel pin pierced through the cork with the tip as a valve and the lower part of the steel pin to keep centered in the float chamber.

 

[Mechanicboy]

Here is the proposal how you can construct a float chamber with a cork to float in petrol.

 

[minh-thanh]

That's also a way...
But I like that it is made of metal - aluminum It's just a float - as long as it floats in the fuel - most importantly the check valve needs to be small and sealed

 

[Jens Eirik Skogstad]

That's also a way...
But I like that it is made of metal - aluminum It's just a float - as long as it floats in the fuel - most importantly the check valve needs to be small and sealed

There are 2 different ways to keep the valve closed:

Float with upper valve:
It depends on how great is the force to resist the pressure of gasoline when the float is strong enough to keep the valve closed without being opened by the pressure. A float with good buoyancy will be able to keep the valve closed without being opened by the pressure when the valve is in the upper part and is kept closed by the buoyancy from the float.

Float with lower valve:
The drawing of the float with the valve in the lower part works best as it cannot be opened by the petrol pressure as long as the petrol level is at the correct level, only opens by the weight of the float. As shown in post #95 I posted the photos of the carburetor and float chamber.

It's just a matter of trying out what works best, whether it's made of aluminum or cork.

 

[minh-thanh]

Hi All !
One designed and tested
I'm trying to solder...

 

[minh-thanh]

Hi All .
Just an announcement
I have completed some important work and now I can get back to the project, will update soon

 

[minh-thanh]

Hi All !
An update :
I did some tests with the float
It floats quite well in water , but not with gasoline - something everyone probably knows - Although testing with gasoline does not have the weight of the check valve

I reduced the weight of the float and tested again with a weight of the check valve : all of them float quite well in gasoline

Next step : I will design a carburetor according to the test and when machining the float I will make it lighter