Fuel Rail Machining

[Orange65]

I am trying to find the dimensions of the holes in fuel rails for the injector. Are they the same as the fuel injector bung? If not, what are the diameter and depth of the hole that the injector seats into? I know that various companies sell stepped drills for this, but why would I want to spend $100 plus for a stepped drill when I have a complete machine shop at my disposal (including all standard size drills)....

[Beagle]

http://www.sdsefi.com/techrail.htm has some good information. I have another link somewhere that has dimensional drawings of the injectors, will see if I can find it.

Megamanual has information as well -

http://www.megamanual.com/v22manual/minj.htm

The manifold injector bungs are 0.530"-0.535" inside diameter [about 17/32" or 13.5 mm]. The fuel supply rail bungs for the top of the injectors are the same size

AFAIK, it's the o-ring doing the seal here, so I don't think you need super fancy stepped anything. I know BBR built a couple of maniolds, maybe he'll chime in. BKB or BOSSMan ?

[BKBridges]

What he said... You want somewhere between 6 and 12% squeeze on the o-ring. We cut em to dia 0.532 with a generous lead-in radius to help the o-ring in. One of the things you cant play with much due to leakage and or fitment...
Injector height varies depending on the injector style you are using.
BKB

[Orange65]

Thanks guys. I knew I had found that info somewhere but I could not "refind" it this morning when I was looking for it.

[CDMBill]

Several companies supply a specific bit for doing the bungs and rails based on the various injector sizes like the Bosch style in the illustration above. Not cheap so maybe someone would loan you one, but it cuts the complete hole you need with the radiused entry, bore size, nozzle bore and radius all at once. This is really helpful should you want to build in some angle on the injectors in order get closer to an ideal relationship to the port and the intake valve angle. see below.