1jz injector boss bung seat install question

toy4speed

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#1
Hello All, I have a 1jz in my Mk2 Supra, been running it for about 6 yrs, pretty awesome setup with top feed 1000cc injectors, fuel rail, bolt on stuff. Because of a recent engine miss, backfire, started checking everything, reviewing parts, do some maintenance. I decided to pull the fuel rail and injectors, got to thinking about the various ways to adapt the domestic style injectors with 14mm O-rings top and bottom to the injector port of the manifold. There are aluminum bosses (or called injector bungs/seat, etc) like what DM and many suppliers sell that appear to be pressed onto the port hole of the manifold, with some sealant like FIPG or similar, then the bottom of the injector with its 14mm O-ring is fitted into the boss. There are also some bosses that seem to have a standard O-ring on them, that is pressed onto the manifold, and apparently seals, then injector is inserted as above. I somehow installed my injectors with a large grommet on the bottom of the boss, pressed onto the manifold, then injector inserted. Been years, so can't remember how or why mine were installed this way. Perhaps was thinking to mirror the stock style of injector fitting?

Anyway, I attached a pic of my injector and boss, with the black grommet attached. Interested in sharing others feedback on install methods, and any issues with boost/vacuum leakage. My engine ran pretty well, but now I am thinking maybe I had some leaks all these years and didn't realize it, and I was missing out on even better power! Appreciate any input!

Don
boss and grommet to head.jpg boss with grommet.jpg ID and DM injectors.jpg
 

hvyman

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#2
Boss goes into manifold. Injector goes into boss. You don’t use stock seals.
 

toy4speed

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#3
Thanks for the reply! Would you just press fit the boss to the intake port, or use some sealant like FIPG on the bottom of the boss? I may have been loosing a bit of boost all these years, but only more noticeable past year or so. Just want to do it right.

Don