Want to be

Does anyone know how to tell if my car actual needs the rubber fuel rail spacers? Please note, i can't find my spacer or remember if i had any. I took the car apart a year ago or so.

When installing my injectors on the DS, i accidentally pushed two injector caps inside the engine, which led me to believe i needed the fuel rail spacers.

My car was manufactured in Jun of 1987.

After installing the spacers i noticed a big gap between other parts connected to the intake.

Its possible i have a stack up issue since i have new gas lines installed for the back side of the intake.

I hate to take off the gas lines because of the problems i had getting them twist on the threads.

Tomorrow, im going to try and install the PS fuel rail to see if i have the same issues with the spacers. I have a little more wiggle room on the PS side. The PS injectors have new caps, so hopefully i don't push more through.

I also wonder how far the injectors need to go down inside the intake. Im thinking i might have the updated fuel rail.

Does anyone have measurements of the fuel rail arms length that stacks on top of the thread screw?

In the next few days i believe i will be able to get a measurement of a friend early 1987 car but for now i thought i would ask.

I don't think the PET provides details of the differences of the two fuel rails.

Im sure its mr. Obvious

This seems to be my show stopper to nearly finishing the loooooooooooooong project of a top end rebuild.

Hilton

The big O-rings on the injectors don't stick down very far at all - they sit in the foot of the intake, and not below it - the topmost point of the o-ring should be a couple of mm below the top surface of the intake foot.

If you mount just the 1 and 4 the injectors in the rail and clip them in, then push the injectors into place, it should be obvious whether you need the spacer - the early-S4 spacers are about 8.5mm thick from memory estimation.

I can measure both cars when I get home this evening if someone can't find the measurement or info before then.

Want to be

Yes please measure if you can tonight. The spacer width is supposedly 8mm thickness.

Thanks for the help!

Chalkboss

I echo Hilton... on my 87 without spacers I could see the top of the o ring when it was seated all the way into the injector hole. They seat into the recess but you can see the top of the o ring. It should be obvious whether there is a need for spacers.

worf928

Post a picture of the intake centered on the spot where the rail mounts.
You either have a threaded stud or a threaded hole. Former is no spacer. Latter is spacer. If spacer, order the correct spacer - called a "bonded rubber buffer" - as thickness is important. Too thick will cause a vacuum leak. Too thin won't support the rails.

Put injectors in rails, then mount rails. Always pressure test before starting.

Hilton

Or you have something else Stud which requires spacer

(this was dealership work I was undoing - part of fitting a warranty block to the car. Similar spacers have been reported by other early 87 owners)

I'll go attempt to take some measurements of the fuel rail on each 928 and report back, as I've got one with the longer fuel rail legs, and one (pics below) with the original S4 fuel rail design.

Hilton

Here's the measurement on an 89 S4 which had no spacers from factory:

34.8mm

This is the distance from the top surface of the fuel rail, straight down to the top of the foot where the nut seats when its bolted in place. I removed the fuel rail cover and measured at the point shown in the pic (front foot of the right side of the car)

If your fuel rail measures that, then you don't need any spacers. The earlier S4 fuel rails have legs which are 8mm or so shorter, will measure the same dimension on my 87 tomorrow to confirm, but I'm guessing it'll be around 26.4mm

Want to be

Fantastic! I measured mine and it's nearly the same height. So my car does not need the spacer. This would explain why I am having so much trouble attaching everything. Gosh I spent a long time trying to find a spacer or washer.
We'll I post my washer size I found for others to use later. I'll post later tonight.

Thanks again!

worf928

Hilton has hit on he other variation: Fuel Rails. The early '87 intakes with the bonded rubber buffer (spacer) that threads into the threaded hole use specific fuel rails.

You can't mix and match the parts unless you futz-around with non-stock bits.

Keep in mind that the injector is ONLY located by the fuel rail. Thus, it is vitally important that the injectors be mounted in the rails and clipped before installing the rails. If you have to futz with spacers because you have mix-and-match parts, futz with rail height only with the injectors in the rails. Make sure that the lower o-ring seals against the bore of the intake. You have a couple of mm to play with. Not a lot.

Never insert the injector in the intake and then try to install the rail. That is a recipe for a fuel fire fed with pressurized fuel from a leaking upper injector o-ring. A leaking lower o-ring is an intake leak: vexing, but not a clear destroy-the-car fire hazard.

Last, always, always, always, pressure test the fuel system by bypassing the relay to run the pump.

DR

One easy way to spot the early vs late fuel rail is to look at the relation of the mount to the upper injector socket. If the mount is even with the injector socket it is early (upper rail in pic below) if the mount is longer it is the late version (lower rail)

Sorry for the fuzzy pic..



Cheers,

Dave

Want to be

Awesome help guys. This will help others with questions about their early s4's down the road.

After a few bends on the fuel dampner bracket and mounting the nuts . I was able to attach everything.

The injectors look good!

Started to work on the other side but found out I'm missing one nut.

I would assume its a m6 nut. I'll need to visit ace hardware tomorrow .

I'll post pictures soon. I just need to become a member.

dr bob

Find the nut. Seriously.

Rob helped with my intake refresh, and we had one of those "sunken ditch' momnents when an injector connector bail (the wire clip) went sproing and managed to drop into an injector hole in the intake. Got it back out OK, but could have been a serious problem.

If nothing else, plan to rotate the engine --by hand-- a few or more times just in case the nut did end up in a cylinder. I think Tony shared a bit about doing the rotation, and finding that something had in fact fallen into a cylinder.

Want to be

Everything was covered so I don't think a nut ended inside the engine. The only thing that fell in was a injector cap. I'm confident to say it's lost on the garage floor.

Thanks again for the help.