I Tried UPGRADING My Vacuum-Modded LEGO Briggs & Stratton Engine...

[@DeltonAdamsLEGO]

Before you comment: I will NOT be making any large changes to the engine, such as reducing the cylinder size, and I will NOT be lubricating the engine. I appreciate all the comments from the previous video, but please read the comments before leaving one yourself!

[@GamerTag700]

Also a small change can you seperate the chambers where the vaulves are and have 2 entrances 1 for both side

[@DeltonAdamsLEGO]

@@GamerTag700 I could, but I'm going to work on other projects right now. I might come back in a few months and try to remake this though

[@GamerTag700]

@@DeltonAdamsLEGO ok

[@Tjandeli]

Also check the timing of the valve of the engine

[@legoenginemechanic101]

Awesome video! Wow so cool! I wished my comment helped!! This time it seems like there is something wrong with the valves lots of leakedge and something is off with the timing. How you looked at other LVE flatheads? Maybe watching some videos or tutorials could help. I wish you could keep it as close to the design as possible

[@GamerLeo4543]

Great video! If i may give some tips, here they are: I would recommend testing to enlargening the intake port (where the vacuum hose is) from a 1x2 stud to 1x4 stud. If the hose wont seal properly 1x3 stud should work too. Technically the intake valve could also be enlarged too from a 2x2 to a 2x3 or 2x4 stud. I have noticed personally if the intake is too small, you aint using the full potential of the vacuum. A lighter piston is also recommended, however that could risk the need of using glue. You dont need to make the piston itself smaller, but just making it thinner. Keep in mind that the piston balance could be affected. (It starts to wobble)

[@xmysef4920]

Hey, two things, your timing is a little off, and use different cam profiles. The ideal cam is long duration and low valve travel.

[@DeltonAdamsLEGO]

If you're talking about the timing when I'm showing the valves, that's just before I timed it. I did a lot of experimenting with the timing and I never got it to run. Also, what other cams could I have used?

[@WalkerO-dp8jq]

@@DeltonAdamsLEGO there are these small half wide technic beam pieces that have 2 axel holes, you could use those with a technic spacer (the one that accepts the technic pin) to make a roller and put the push rods on the roller with a 2 by 2 base for it to roll on

[@GamerTag700]

Good Job on the fix

[@JsGarage_]

Hey dude!, a few ideas: . make sure the exhaust spring is harder, the vacuum is likely able to pull up the exhaust valve because of the soft spring. . Lube. Friction really is your worst enemy on any lve, i understand you not wanting to use any but even something simple like water wil work for at least a little bit of time Make the cams open less, ideally make them open half as much . Loosen up your axles a little, friction again . Make sure all your walls are smooth, cant have the piston stopping on little edges

[@Dudeface167]

0:14 never been in somebody else's video before :)

[@severinghams]

the sheer amount of small bricks used for the cylinder walls leaves a lot of room for air to enter through.

[@DeltonAdamsLEGO]

@@severinghams it's actually not as bad as you'd think, really

[@vacuumpowered6119]

I don't use any lubricant for my engines and I get mine to rev up around 3-4k rpm so no you do not need lubricant

[@braxtondixon]

It's not completely sealed you could but saran wrap in-between. The brings without lobbing it

[@ViperzDesign]

The 2x2 valves are alright but ideally the poppet valves are best because they seal well, also try changing the camshaft to a 1x2 lift arm beam rather than that egg cam.

[@Titanic4]

The valve with vacuum should be open slightly after bottom dead center while closing near the top dead center, with the intake valve opening after top dead center and closing near bottom dead center. This should give sufficient torque to overcome friction given by the plastic mechanical parts. From what's heard during the attempts, the vacuum valve closes while piston is in the middle of its stroke. This setup doesn't give sufficient torque to keep running.

[@DeltonAdamsLEGO]

That's just because of the cam lobes.

[@noahsalvacion5339]

Yeah i saw the "exhaust sport" is too small and the exhaust port gives the cylinder air

[@DeltonAdamsLEGO]

It seems to be large enough for this one

[@noahsalvacion5339]

Yes it needs a large enough exhaust hole because if the exhaust hole is too small i cannot have more air inside of it

[@GTech_builds]

i think for optimum performance you might need DOHC and 4V head the other thing is you might need to have the valve offset closer to 90 degrees from the piston because other wise you might not have enough pull time

[@DeltonAdamsLEGO]

I'm not going for performance. I'm just trying to get it to run at all

[@GTech_builds]

@@DeltonAdamsLEGO no that's fair but i built a copy o your engine and found that it needs much bigger valves to run (3x3 min)

[@DeltonAdamsLEGO]

@@GTech_builds somebody else made one too, but it ran fine with the 2x2 tiles

[@GTech_builds]

@@DeltonAdamsLEGO must be my poor vacuum cleaner then

[@Ollisaa6095]

make the valves open more? it should help. Also check the timing: the correct timing should be camsaft 90degree to cranksaft.

[@DeltonAdamsLEGO]

Timing was right, but the engine ran fine with the original lobes from part 1

[@TheRealRub3n]

I suggest you make it so that the vacuum sucks the piston up and then sucks it down again using the valves rather than suck it up and the piston staying at the top of its stroke

[@DeltonAdamsLEGO]

That would require too large of changes to the overall design

[@elputinlegomastery8054]

the exhaust valve and the inlet valve are open too little time! Maybe you should adjust them to be open a longer time.

[@DeltonAdamsLEGO]

That's just due to the cam lobes

[@JB_Lego]

try to put the cams up a stud to give more vacuum to the cylinder

[@DeltonAdamsLEGO]

All that would do is make the valves not seal. I understand what you mean though

[@JB_Lego]

@@DeltonAdamsLEGO yea

[@jedbench5887]

@@DeltonAdamsLEGO You could make the cams bigger or the valves larger so that more suction gets to your cylinder. The issue could also be that your valves are not sealing well enough which would make it not run at all.

[@redneck_sct]

You need a throttle mechanism

[@DeltonAdamsLEGO]

I don't really think that would improve anything. If it ran well, the yeah sure

[@QuestionableFurry69]

the valves might not be sealing properly

[@DeltonAdamsLEGO]

That could be one problem, but it didn't feel like there were any major leaks

[@BrickEngines]

Well looks like the only way to perfect it, is to put bigger valves, but it wouldn’t be original so can’t do anything about it.

[@DeltonAdamsLEGO]

But the weird thing is, a lot of people have told me the valves are a good size for this engine

[@GumerTheGum]

strange... I've got one too and it revs up to 3500 RPM without any problem. Maybe the timing is wrong or there is a leak from the cylinder?

[@GumerTheGum]

And the cams can be the same. they work good in my engine.

[@DeltonAdamsLEGO]

It could literally be anything at this point

[@xmysef4920]

I very much doubt you got 3500 RPM with a poppet valve vacuum engine. I’m gonna assume you mean a slide valve vacuum engine?

[@GumerTheGum]

@@xmysef4920 yes, poppet valves were installed, spring only on exhaust, 105 degrees timing. I measured it.

[@xmysef4920]

@@GumerTheGum I suuuper doubt that. Either your tachometer was wrong or you’re lying. I can bet it was a cool engine, but ain’t no way an engine like that is gonna reach 3500 RPM. Even 1000 RPM is impressive to reach with a poppet-valve vacuum engine.

[@Wreckedftfoxy]

ur timing is off and the vacuum is like a single acting steam engine but inverted so instead of pushing it pulls air so yes u want everything to happen within 2 strokes so it should be intake power and exhaust

[@DeltonAdamsLEGO]

The timing on this is perfect, and I did a lot of experimenting with when the valves open and close

[@external316]

5th. Also I’m saving this to my watch later (I got stuff to do)

[@Anisalenanis]

Still didnt work sad but i could maybe make one like your but I wont spend 3 dollars i an make one like your it should be the same as yours

[@DeltonAdamsLEGO]

Good luck with making your own!

[@Anisalenanis]

@@DeltonAdamsLEGO i also join your discord server

[@egor.dmit.]

Жду такой же только v8 😊

[@picaman485]

Yay you saw my comment😊😊 No way you hearted my comment 🥹🥹