need efi/machining help---soon

[curious]

ok our teacher told us to go and find some scrap to use in the lathe so we can get a hang on it. i grabbed a 1x12 piece of 6061. my plan was to machine it for injector bungs since a set of 8 can run $60+. i ve milled the outter diameter to about .830" or so and my intentions are to grind it even farther down to just above .750" so when i use the mill and a 3/4" smooth end mill bit the bung should drop right into the intake. what are the dimensions i should use for the injector bungs? O.D.? I.D.(s)? height?
mopar action used a .950" tall bung with an unknown O.D. and 3 different I.D.s so the injector rests in the bung and the o ring has a seat. i plan on working on this tommorow and need some input ASAP! thanks to 'all.

[turbododge]

I have done these a couple of ways. The bungs you buy complete have a finished ID and OD and a shoulder on the top, which is handy for fixturing but has no functional use. I would have to measure an old manifold to get the actual dimensions, if no one has them memorized.

What I have found to be very useful is to make the bungs very consistent (within .0005) in outside diameter and slightly above a standard end mill size (like 3/4). I will then plunge the end mill for the manifold holes, and the holes will be slightly undersized for the bungs. I then bore the holes in the manifold to about a .001/.002 press fit for the bungs. The press fit makes the welds less likely to crack, and weld fixturing easier. The weld fixture can then be a bar with bolt holes at the same spacing as the bungs and bolted through the ID of the bungs to hold them at uniform height. The press fits holds everything in place to the manifold.

The last manifold I made, I left the ID of the bungs about .010 undersize, because previous ones had opened up a bit from the welding. They didn't leak, but were a bit loose for my liking. After welding, I went back in the mill and bored them to exact size and position to match the fuel rails. This worked very well, and everything fit perfectly.

[curious]

so what are the inside measurements? heights?

[dewme5]

those measurements are going to depend on which injectors you use.

http://www.sdsefi.com/injectors.htm

check this site for a little info

http://www.sdsefi.com/tech.html

this one too

http://members.tripod.com/~Red_Header/LTH2index.html

search around that site too. some good header info.

[Hammer 74]

I have a SpeedPro one here and the measurements. The small OD is .750 and 1.05 long. The big OD is 1.000 and .500 long. 1.550 overall length. The ID thru is .550 and the Injector ID is .660 and .350 deep with a 45 degree transition to the .550 ID. Light chamfer at the top ID for smoothe injector installation. I used and intake that had bosses for EFI already so it was easier for me. Also I angled my holes for the injectors 18 degrees in toward the centerline of the intake. I have measurements of the hole locations for the intake and rails if you need them or I can explain how I figured them out.