Flamethrower Help

I recently built this propane fueled flamethrower setup and can't seem to get it to ignite. I have plenty of spark but my plugs are in 10 inches from the tip. I thought I might be getting too much propane so I regulated it down to about 20 psi. The propane is fed into the tailpipe via 3/8 copper lines and dump into the pipe about 4 inches in front of the spark plug. I can ignite the flames with butane torch and they will stay lit, but I can not get them to ignite with the plugs. I'm thinking there's not enough fresh air to get a good burn. I used to make propane potato cannons and know that if there is too much propane and not enough fresh air that it won't fire. So I'm thinking that I need a way to get fresh air in the system by adding a vent line that'll siphon fresh air into the direction of the exhaust- it's got to be better than just drilling holes in the pipes. Or should I sleeve the tail pipe with an inch larger diameter pipe and run the propane and spark through it so the direction of the exhaust would get fresh air flowing through the front of the sleeve. I'm kinda lost, I thought I knew what I was doing but its been very frustrating....especially when you have a group of friends standing around waiting to see the show and then you get nothing.....buzzkill.

 

too much propane pressure in my opinion i would start way down like a 1/2 lb and work from there i think your just blowing out the spark

 

I didn't know propane was used for this. I thought it worked off unignited fuel/air from the exhaust. Is doing it this way safer?

 

that's the traditional way, cheeters and beeners use propane.

 

Move the plugs to the end of the pipes...more oxy there.....

 

I started off from zero psi with it sparking and gradually went up from there and got nothing. When I manually lit it was back down to about 5psi but it wouldn't stay lit so I just kept on increasing it until it didn't blow itself out.

 

You are missing the oxygen needed to burn.

 

Will those pipes always stick that far out?

 

Only forklifts should have that view from the rear.

 

I can't help you. I have flamethrowers on my car...........
I use propane on my BBQ.

 

This is why people have those huge tips, for the air mix. Move the plugs nearer the tip also.

The bigger tips work with normal flamethrowers also. Small tips give the pencil tip flames, larger gives the fluffy sustainable flames.

 

I figured propane is safer than spraying gasoline into the air....and easier on my motor. I don't know why people think it's like carrying around a crate of old TNT or something. It is fairly safe, and used inside of buildings in forklifts and floor scrubbers. I'm using all LP approved fittings and valves so there are zero leaks. Hell, you can't even shoot a propane tank and make it blow up.....don't you watch mythbusters? And thank you trolls for putting me in my place and letting me know how much cooler you are for not using propane on your flamethrowers. Let's all agree that they are pointless and there just for ooohs and ahhhs. So the natural vs propane argument is like two jersey shore douches arguing who uses the better hair gel.

 

I like my flamethrowers. I don't inject, but I have thought about it.

 

They don't ignite forklifts or floor scrubbers.

 

Different strokes for different folks.