Mcmaster check valves are a pretty good price just as saefroch mentioned, and will probably last you a long time. I very much recommend it.

Now that I have been re-enlightened to this idea, I think I will finish my pump (One emoticon i havent used yet)

No one on the forum can even diagnose the problem if you are not more specific.

Pictures always help too.

The only thing I can go by is that you are not fueling your chamber correctly. Please use the search function to figure out how to properly make a fuel meter.

Fill it with this

Its great! I like it alot and makes me want to get back to fixing up my old cannons, just wish I had the funds.

Great that you made it all metal now, definitely giving your metal fittings some respect there.

Happy Shooting!

You can get away with that, but you will be depriving it of power unless you get a large sprinkler valve, which can get expensive.

Ya that should be good enough, with will help alot. You could try and mount the fan in the chamber too to mix the mixture and help combustion peak pressure.

Yea thats true, I would stick with just a regular combustion.

Something to consider though is making sure you purge the chamber well, because it will probably be of smaller caliber, unless you want like a 2 inch chamber that should be easier to clean of spent gasses.

Well thats fine as well, a burst disk isn't necessary but it can improve performance with better build up of pressure. But its more of a hassle to reload every time.

And you can't really make it a semi auto if thats what you mean by pulling the trigger every time. The best way to do that is with ...

An O ring would definitely be beneficial, and sparking idea sounds great as well.

You also don't need to attach schrader valve but a burst disk will definitely make it sound louder as a normal combustion.

Well first off there is no problem creating a combustion rifle and its a feasible concept and not really stupid at all.

You probably want a tight seal just like any combustion cannon.

You only need a tiny spark to ignite the mixture. It doesnt take that much energy to ignite the mixture. A bbq ...

im sure if they had metered propane the thing would have blown to bits. it was pretty cool though. I wonder if you could make a cannon entirely out of duct tape.........

Well pretty much, they actually did but not the support system and it did work fairly well. And i love how they must put a ...

Decrease pilot volume and use a valve that opens quicker to release the pilot volume.

The cannon reminds me of my cannon, which still need a support system and a barrel support, man in lazy.

Well good for you!

1. Well it doesnt have to be attached to your piston but it is necessary because that absorbs the shock when it shoots back and if thats not there to absorb that shock then the fitting will absorb the shock which can damage or break the gun.

2. Lubing the piston makes it easier ...

Sounds good, now all i gotta do is find some time and stop being lazy.

Ill get some as soon as i can.

EDIT: Although, i still might take this cannon apart not only because of leaking problems, but also because of the fact that its just to big and i would want to redesign the valve.

Or i can just ...

O well its okay then cause i was gonna bring this up, but probably wounldnt have if you didnt do this.

Well i think im gonna take her apart because its hard to fix the leaks. There are leaks in the parts that i cemented and i dont know it happened. So i would have to take it apart to fix it and ...