SPINOFF: Aluminum injector return rail.

[04_6.0]

Not to take away anything from ADV, (heck if he had sets to buy i would get one). But with all the buzz in his thread i thought it might be better to put our thoughts here instead of getting that one too clutered up. I just want to get the thoughts of the members on this forum before getting into the design phase. I am going to pull measurements on a head that has the injectors still in it when i get home tonight.

My questions are:

1. Is the depth of the injector sitting into the head vary from injector to injector? (distance from head to top of injector).

2. Is oring position the same on every injector?

3. Is the distance of the oring circles the same from injector to injector?

4. Do all injector use the same size oring?

5. What size oring do the factory caps use?

I am thinking 1/8" npt on either ends of the rail. That way the end user can decide if there will be a tee, an elbow, or a plug. I am thinking two small brackets with slotted ends that will hold the rail in place to the valve cover gasket bolts.

I thought about having one injector start leaking that you would have to replace all the orings on that rail when removed. If the orings get old and start leaking you would want to change them all anyways right? Let me know what yall think. As far as getting the machine work done.....my best friends family has a large machine shop and has CNC capabilities. I have drawn many parts for him, his family, their buisness, and other friends to build.

 

[swervyjoe]

I'd make stainless caps and weld/fuse hard thick wall tube between them as opposed to milling a manifold out of a solid chunk

 

[04_6.0]

Once they are installled? To take up the difference in height of the injector? I think that would mean a lot of extra work to get them done by whoever gets them. I guess make a jig to keep the caps to stay straight and not warp when weld/fuseing them together.

 

[mblaney]

I don't think a solid rail will work, especially if you are using materials with a different coefficient of thermal expansion than cast iron. The resulting movement would constantly be causing leaks. Also, the tolerances you would need to maintain proper o-ring contact would be tough to manage if you are welding parts together.

If this was a face-seal design then I could see it working but trying to line up four through-hole connections in an almost zero-tolerance configuration will be very difficult.

 

[Knuckledragger]

Actually, cast iron and aluminum generally have a pretty close coefficient. Cast iron grows 1/8 inch per foot (melting point about 2400F), aluminum grows about 1/10 inch per foot, but melts at about 1300F. At engine operating temperatures, they are probably pretty close, hence so many Mfrs. using aluminum heads on cast iron blocks.

 

[OLDBULL8]

1. Is the depth of the injector sitting into the head vary from injector to injector? (distance from head to top of injector).
I would think the tolerance would be close to +/- 0.003

2. Is oring position the same on every injector?
Yes, within +/- 0.005

3. Is the distance of the oring circles the same from injector to injector?
Yes, within +/- 0.003

4. Do all injector use the same size oring?
Yes. For Ford/Navistar IDI engines.

5. What size oring do the factory caps use?
2-111--- 7/16" ID X 5/8" OD

[/QUOTE]

Measurement tolerances above are standard for manufacturing of those.

 

[mblaney]

Agreed! But the rail would not be in intimate contact with the iron so would probably be significantly cooler than the head. The difference in expansion (due to difference in operating temperature) would probably be enough to create problems.

 

[laserjock]

^^^ What he said. This is a cool idea. Get enough ideas together and maybe something interesting falls out.

Subscribed.

 

[riotwarrior]

Ok this is a theory discussion right?

Then I would say machined stainless caps, add welded on fittings for AN style lines and use all AN fittings between the caps and all connections.

That would be about the best allowing for differences between heights of injectors or slightly off placement location in the head.

Add two internal grooves in the caps for the two O rings and that cap will LOCK in place just fine!

JM2CW

Al

 

[Agnem]

This thread makes my brain hurt.

 

[OLDBULL8]

[B]Just remember, there is only about 0.020 squeeze, 0.010 to a side on the o'rings, so the center to center of the caps with a manifold would have to be damn close, not more than +/- 0.003 CC, minimum squeeze is 0.007 for a seal. Then you'd have to take into account the tolerance of manufacturing of the heads and injectors. Just something to think about.
[/B]

 

[OLDBULL8]

This thread makes my brain hurt.

Mine is spinning like a centrifuge.

 

[G. Mann]

Bottom line is the design of the caps with the O-rings is a poor design for sealing.

It relies on the tension of the O-ring material only to make the seal. That tension weakens with the age of the O-ring, there is no way to "tighten" the amount of contact force on the O-ring, consequently, it is "programmed to fail" as heat and age attack the material.

The Caps themselves are plastic, so they have little in the way of tensile strength to contribute to the "circle of force" applied to the contact area of the O-ring.

Two schools of thought apply.. the "hell, it's cheap to replace, fixit often, watch it for leaks" .... and the "make it last for ever no matter what it costs" school...

Obviously... Ford engineers and marketing department went for "it's cheap, use it" plan.

30 yrs later... we still run them, plan for another 30 if we can.. so let's design a cap that has an internal cone, with screw thread, that tightens against the 0-rings to put an expanding force on the contact pattern on the top of the injector, and actually seal the return fuel path.

I see no gain in adding Aeroquip hose fittings.. the barb / clamp fittings seldom fail, if ever. The cap and 0-ring are the culprits.

 

[FordGuy100]

I would rather someone figure out how much they can actually increase the return hole size in the injector, then tap it for a small banjo bolt. Same thing as the cummins use.

 

[04_6.0]

Yes this is brainstorming phase. I'll hopefully get the design done tomorrow and cut this weekend or next hopefully before Christmas.

Only thing is we can not do our return lines like a cummins engine. The injector is held in place by a outside nut on the injector allowing the injector to be aligned the correct way then torque the hold down nut to spec. Attach the return lines and your done. Our injectors are not aligned the same exact way on every injector. I know on mine I have some return hole that are 60-90 degrees off from one another.

I too am skeptical about the manifold but I am willing to make a few sets and give it a try. I want to make an internal groove to hold the orings in place.