Mongo

I bought a set of S300s for my S4 and some injectors a while back. While they are 24lb, these Design III injectors appear to be missing the groove for the injector clips. Did I buy the wrong ones?

bureau13

I remember reading that some people were cutting their own groove in some injectors to fit the clips...but I can't say for sure if they were this model. I know people have used Design III, although they seem to be thinner. I'm not sure if any of them have the groove?

ROG100

Get your Dremel out a cut a groove.

Mrmerlin

read this.../

https://rennlist.com/forums/928-foru...fuel+injectors

Hilton

The type you have are no good - you can't cut the groove in them.

FredR

These injectors look "too narrow" at the top section-presumably that is what Hilton alludes to in his post.

Check measure the diameter of your stock injectors at the ring groove point and measure same on the new ones- I would hazard a guess that there will be a few mm difference.

Rgds

Fred

Jfrahm

I'm sure some zipties or safety wire would sort it out.

Jfrahm

Full disclosure, I have three sets of these 24 pounders and should sell one or two at some point. Long story. However a twist of safety wire seems to do the trick perfectly. A full harness could be done also. The light blue injector is secured as well as the other (stock 944S2 I think). A possible alternative might be an O ring in place of the wire.

*EDIT* a Dash 012 O ring stretched over the injector top in place of the wire works perfectly. The clip is harder to get on but holds well. The upsides of the O ring is that it won't ***** your fingers and will not fall out of place with the clip removed.

jcorenman

Gasoline, 55 psi rail pressure, aging hi-voltage ignition wires and red-hot exhaust... Seriously?

Keep in mind however that not all 24# injectors are the same. Flow rates and latency differ, and an ECU maps created for one injector won't be appropriate for another.

Jfrahm

Sorry if my real-world experience does not comport with your internet-based speculation. Or maybe I'm unfamiliar with the hidden titanic forces that might rip a ziptied injector out of the fuel rail? Probably. Not.

I have 19's in my blower car right now and FWIW they seem captive despite not having any clip or alternate retainer. Maybe some manifolds lack a step in the injector well but I recall seeing one in the 87, and that injector will not move down at all let alone pop out of the rail. The injector body might prevent it if not whatever I thought a saw in the manifold. So in my application the clip might just be for assembly. Maybe in other years the clip more critical and since it's easy you might as well run one. The stock clips are not very strong however and so I doubt there is a great deal of force acting on them.

I've heard of injectors shifting down and dislodging but my first thought was that it was a human factor problem.

-Joel.

Rob Edwards

Joel, start at post #18.

https://rennlist.com/forums/928-foru...-cranking.html

Probably a human factor problem, but your bailing wire trick is also a pretty epic human factor problem too. It may work for now, but what happens when that o-ring dries out ever so slightly and that bailing wire relaxes ever so slightly after a couple hundred temperature cycles and all that vibration, in the next few thousand miles?

I make enough human factor errors that I need all the safety margin I can get. Which includes buying injectors with molded grooves where they belong, and properly attaching them to the rails.

Jfrahm

Modding cars isn't for everyone. However a solution that holds the injector in place adequately is a solution regardless of anyone's ability to mock it.

My blower car did not even have injector clips on it when it came into my possession, and it'd run for years and probably at least 5k-10k miles without them. I'm not sure yet if it's possible to dislodge an appropriately sized injector, at least in an 87 S4, if the rails are mounted properly. Maybe with a hammer and chisel. Maybe in other years the fit is different.

All that being said I think one should use a retainer even if it's pointless once the rail is installed, and when I settle on injectors for the blower car there will be one in place. It's not challenging to do adequately if you are OK with tolerating some ignorant mockery.

-Joel.

Jfrahm

Was there a resolution to this? The owner suggested a bad O-ring. Only Stan mentioned a clip and there was no confirmation that the clips were left off in that thread. I do not see a way to dislodge an injector downwards, I will check again for the protrusion I noted when I installed these injectors when I have them out again. My current speculation is that the bump in the port where the injector spray is introduced provides a ledge that the injector cannot pass.

Seriously I can't dislodge them by hand. But then that's just real-world experience.

-Joel.

Rob Edwards

'87 rails are different from '88-95 rails, the early '87 with rubber buffer mounts and later '87 getting aluminum spacers, so maybe there's a detail difference that we're both talking past here. All I know is that with '88-95 fuel rails, if you mount a stock injector plus its o-rings without a retaining clip on it, and bolt the rails down, you can absolutely move the injector up and down with your hands. That's been my experience based on an 'n' of about 6 engines' worth of fiddling with fuel injectors. Hence my paranoia about clipping them properly.

How do your fuel rails mount to the intake?

Mongo

FJfrahm you have a PM.

I would prefer not to ebay these injectors to finance a different set of design IIIs.

I have an early 1987 car build date of 10/86.