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I am in the middle of replacing all the rubber on my 85 spider. Now deep into the fuel injection rubber. All the posts on the bb here have been excellent help! I am now about to put new rubber gaskets and o-rings on injectors and discovered a difference from OE and am curious what others did. I could not find anything in the old posts that covered this. The OE large rubber gasket (#5 in the enclosed picture 1) has (a) an edge to accept and help center the flange (#4) and (b) is narrower and allows the Bob Seeger ring (#6) to seat in the channel. See picture 2 comparing OE vs new replacement. The overall width of flange/gasket/Seeger ring is 10.3mm (picture 3). The width of the new gasket (BECK/ARNLEY reduct from Rock Auto) + flange + Seeger ring is 12.3mm (picture 4). The new gasket also doesn't really seat well with the Seeger ring as it takes up the whole channel and you have to really work to seat the Seeger ring. The extra width and sloppiness of the flange leads me to believe the injector will not center and seat well into the engine port. Moreover, the extra width means the flange will be pushing the injector deeper into the port. What have others done? Can you get gaskets (part 5) like the original? Do you leave out the Seeger ring to bring the overall width down, but its still wider at 11.2mm (see last picture). Any insight would be appreciated.


FI hose replacement.JPG
two large gaskets compared.jpg


Original gasket.jpg


new gasket with ring.jpg



New gasket no ring.jpg
 

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Are all the old rubbers in decent shape? If so I'd re-use them. Their function is just to hold the injector in the intake - they don't otherwise seal anything. I once had a VW Rabbit - IIRC the injectors in that car were simply a snug fit into the intake - no clamps. Intake vacuum was supposed to be sufficient to hold them in place. (I always wondered what would happen if there was a back-fire...)

Note there is supposed to be a phenolic ring in the intake port and then a rubber O-ring (item #7). This will center the injector. The phenolic rings are NLA so don't lose them. They usually remain in the intake port - if so, leave them there. Attempts to extract them are likely to damage them. If they are not present, lost or damaged, use two O-rings.
 

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I recently went through this on my S4 Spider, which uses the same design but with slightly different injectors, I believe, than the S3. Regardless, do NOT leave out the snap ring, because it shoulders the rubber seal and provides compression to hold the injector in place when you draw down on the retaining flange. I wound up using the original rings too, because I got tired of trying to sand down the fat ones from Rock Auto to the proper thickness, and the originals were still pliable and intact. And as Eric said, treasure those little phenolic rings because they back up the o-ring that actually does the sealing in the bore of the recess.
 

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While the injectors are out I would send them to Cruzin performance and have the cleaned and calibrated. It's worth the 100 bucks and he will send new rubber too!
 
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