Made some new air inlets with barbs for my Siamese Twin

[DeereGuy]

Hello gang, I built this engine several years ago and have always had problems with the hose's falling off.  I didn't barb the ends DUH!  Anyway I needed to make some air inlets on another engine I was building on a team build from the HMEM board and a member there gave me some pointers on how to machine them.  The finished part for the project is laying on top of the cylinder block.  This was an extra I had but the barb is to small in dia. and the threads were not the same size. I ended up grinding a tool just for the barbs and I used it again today to make the new air inlets.

In the photo below you can see the original inlets and on top of the head is one of the connectors I built for the team build #1.  The barbed end on this one is to small for my hose and the threads are not the same so I am off to build two more per Tin Falcons instructions.


The first step was to center drill then drill 1" deep with an 1/8" drill.  This depth will allow me to make two parts.

The next step was to turn the OD to .190 for a length of approx. .400.

I didn't center point the threads for this as a die is much quicker when you have the correct one.  I usually turn the die around after making the threads just so that I can thread as close as possible to the shoulder.

Here we have the threading done and next I will part off the at .100 so the air inlet doesn't jam against the valve once installed.

Now I need to turn a section to a dia. of .200 for a length of .200.  I did this with my parting tool by taking just a little off the diameter at at time.

Next step was to make the barbs with my super custom self made barb cutting tool .  I chose a random angle for my compound that looked good and started barbing away.  I parted off with the barb tool also.  This gave a nice angled nose to the barb to make it easier to get the hose on.

Here is a shot of the ST with the new air inlets with barbs on her and running happily w/o worry of hoses falling off

Here is a short video I took: 

Sorry about the quality of some of the pics and the video, I just the camera and video recorder on my Blackberry.

[Bernd]

Bob,

Very nice. How about a nice pic of that super duper barbing tool? Please?

Bernd

[Mustang]

Bob,

I second that request for a pic of the tool

Andy

[DeereGuy]

Arg, sorry guys I will take a better pic of it sometime this week as I am in the house now and getting ready for bed soon.  In the mean time here is a pic of the finished part I forgot to put in my first post.

[sbwhart]

Nice Job Bob   

Thanks for showing and your engine sure runs sweet.

Stew

[bogstandard]

Just a little note.

In the UK we tend to use silicone model engine fuel tube for for small airlines such as Bob is using, whereas in the States they tend to use plastic fish tank tubing.

The barbed fittings are OK for plastic tubing as it will grip very well, but for silicone you cannot use any sharp edges at all, the pipe will just tear where it comes into contact with a sharp edge, so you can still use a 'barbed' type fitting, as long as you smooth down all sharp edges first.

Also, silicone has a tendancy to balloon out and pop off the fitting, so if possible, wrap the joint with a couple of turns of plastic coated garden wire and that will stop it popping off.

Bogs

[DeereGuy]

John thanks for adding that insight to the post, sharp edges + silicone = bad news...

I haven't forgot about those asking for better pics, I was out in the shop last night but forgot my phone (I use it's camera) and just as I stepped into the shop a fierce thunderstorm broke out so I didn't venture back up to the house to get the phone.   Several hours later I had to evacuate the shop and get back up to the house because we went under a tornado warning.  Thankfully it didn't actually touch down.