ErnestSw

on the left bank I pushed the fuel injectors down as far as they would go and then installed the fuel rail. After hooking up both sides of the fuel rail and the fuel rail mounting screws I tried to install the clips that hold the injectors on to the fuel rail and discovered that the front and rear injectors were not into the rail far enough to get the clips on. I removed the rail and have the injectors properly clipped to the rails but I'm concerned that when I reinstall the injectors already mounted in the rail the front and rear ones will not seat down all the way into their holes.
Any help would be appreciated.

tresamore

Maybe you have an old o ring in the manifold or one got into the rail seat somehow. ?? Its all I can think of. I've done that job on both of my 928's and its tricky to get them all seated. Did you lube the o-rings to help them go in easier?

Greg86andahalf

I coated the top and bottom o-rings with wd-40. I attached the injectors to the rails with the clips, then installed the rails, being careful not to force the injectors down which can crush the o-rings. A slight turn of the injector when pushing down helps get the o-ring in the hole.

When you are done, the injectors should be free enough to be turned back and forth, but not loose. If the injector does not turn, the o-ring is probably being pinched and that is not good. I gave each injector a turn each direction to be sure the o-rings are seated and not pinched.

Greg

ErnestSw

The injectors will seat all the way into manifold AND all the way into the fuel rail. It seems to be more of a alignment problem than an obstruction.

ErnestSw

Greg,
It sounds like it's more critical that the injectors are seated all the way into the rails that that they are at the bottom of the holes in the manifold. I GUESS that as long as the O rings are properly seated in the manifold holes they're properly installed. Do you agree? We're talking about one or two millimeters.

Greg86andahalf

Make sure your clips are on the proper part of the injector. see 1st pic.

My injectors show a slight gap at the manifold as well. This must be normal. I know the o-rings are seated and there are no leaks. See pic 2 and 3
So, I would agree with your statement.

<img src="http://members.rennlist.com/gh/injtop.JPG" alt=" - " />

<img src="http://members.rennlist.com/gh/injbotm.JPG" alt=" - " />

<img src="http://members.rennlist.com/gh/injbotm1.JPG" alt=" - " />

ErnestSw

Thanks Greg, that puts my mind at ease until I run into the next problem.

Greg86andahalf

(pondering outloud) ..The block will heat and expand. with no gap, wouldn't there be strees on the injector housing?

ErnestSw

Greg,
I don't think the total expension would be that much, and there's some "give" in the fuel rail. I wonder how critical the position of the injector tip is. I imagine that there's a minimum distance needed to establish the optimum pattern and a maximum distance beyond which the velocity of the flow fall below optimal levels.

BrianG

Ernst, I locked my fuel injectors into the fuel rails and thought that the bases looked a bit loose in there too, but once I tightened the fuel-rail-to-manifold bolts down they looked better. They do move though.

Z

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by ErnestSw:
<strong>Greg,
It sounds like it's more critical that the injectors are seated all the way into the rails than that they are at the bottom of the holes in the manifold.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">If the injectors aren't seated with a good seal in the holes in the manifold, you get a vacuum leak. If the injectors aren't seated with a good seal in the fuel rails, you get a fuel leak on top of the running engine. There have been a few 928 engine fires from leaks at the injector to fuel rail junction after people installed the injectors. Install the injectors into the fuel rail first, then install the rail and injectors onto the intake as a unit. Lube all of the "O" rings.

BrianG

Greg, did you have any trouble with the fuel rail sitting flush to the screw-pads on the manifold?

On my left side, the thing would not sit flat , but rather teeter-tottered, about 1/8", on that mid-way "head-bump" against the fuel-rail's sheet-metal skirt. Something is amiss, but there are no leaks..... <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />

I guess I'll rip it apart and look for a forgotten o-ring in the manifold, or something.
<img border="0" alt="[grrrrrrr]" title="" src="graemlins/cussing.gif" />

Greg86andahalf

Brian,

Mine sat down just fine. I had the rails and intakes powdercoated. Although the holes in the intake and rails were plugged when P'coated, I reamed then out with a gentle blade to be sure there were no lumps or high spots, especially the rails. It really all fit together quite well.

Did you powdercoat? As I said, that does ad some thickness to the parts.

Greg