I built a plane with a steel tube frame, so I had a lot of pieces of tube with different dimeters and wall thicknesses.  It was trivial to find a size that the injectors would squeeze into.  Then I used a washer instead of a cutting wheel in my tube cutter to add a shoulder.  It is what I'm using as the receptacle in my manifold.  I'm using the stock fuel rails, but it would have been a simple matter to weld the sockets onto a 3/8" tube to make a rail.

MONTY ROBERTS <montyr2157@windstream.net> wrote:

>They make a special cutting tool with a counter bore on it for this job. I'm sure you can accomplish the same thing with a drill, a counterbore, and a couple reamers.
>
>Monty
>  ----- Original Message -----
>  From: Charlie England
>  To: Rotary motors in aircraft
>  Sent: Monday, May 21, 2012 7:37 PM
>  Subject: [FlyRotary] Re: Drilling injector rail
>
>
>  On 05/21/2012 05:39 PM, jskmberki@windstream.net wrote:
>Does anyone know the sizes and configuration used to drill a fuel rail for RX8 injectors?
>
>I think 7/16" will accommodate the first O ring.
>
>Does there need to be a larger diameter to seat the second O ring which is different in shape?  It is located close to where the electrical connector branches out.
>
>Thanks for any help.
>
>Joe Berki
>
>
>--
>Homepage:  http://www.flyrotary.com/
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>
>I've got a factory pair of rails. I can measure the diameter of the injector cups for you tomorrow. If you can use them, I'd be happy to let them go for whatever I paid (was pretty cheap on ebay). This set is for 4 injectors: the 2 in the center housing + 2 on the intake manifold, complete with hoses.
>
>  Charlie
>
>