Read the how to articles 90 primary and secondary injectors orings question...

[Corvette95]

I have a complete set of Viton Orings for my injectors from Jerry, I read the how to articles, seems the 90 is different, which injector(s) primary and secondaries should have orings where (to install) and which ones do I leave off? Being 2:37 AM I might have read it wrong, but didn't quite get it. My car has recent RC injectors.

[tf95ZR1]

https://www.jerrysgaskets.com/lower-...llation-guide/

[Corvette95]

Originally Posted by tf95ZR1

https://www.jerrysgaskets.com/lower-...llation-guide/

Thanks, I had the link before but it had been changed and was not working!

[Paul Workman]

The 90 primary injectors have an O-ring near the top of the injector. No O-ring is needed at the tip. However, the 91+ require an O-ring at the tip.

Installing the upper O-ring in the 90 IH requires a little pic tool to hook them for removal. The new ones I installed, smeared with dielectric grease to make installing the injectors a little easier, but motor oil would have worked too.

NOTE: When I ported my IH's, I completely removed the primary injector boss, leaving the injector tip to 'blow in the breeze' (so to speak).

[Corvette95]

So NO orings AT ALL in the secondary injectors?

Originally Posted by Paul Workman

The 90 primary injectors have an O-ring near the top of the injector. No O-ring is needed at the tip. However, the 91+ require an O-ring at the tip.

Installing the upper O-ring in the 90 IH requires a little pic tool to hook them for removal. The new ones I installed, smeared with dielectric grease to make installing the injectors a little easier, but motor oil would have worked too.

NOTE: When I ported my IH's, I completely removed the primary injector boss, leaving the injector tip to 'blow in the breeze' (so to speak).

[Ccmano]

Originally Posted by Corvette95

So NO orings AT ALL in the secondary injectors?

The O-Rings mount into the top of the injector housing. Look at it from the top and you’ll see a groove cut into the housings. The o-rings go in there.
H

[A26B]

The link to Jerrys Gaskets works, just checked it.

https://www.jerrysgaskets.com/lower-...llation-guide/

To prevent a robot onslaught, it is necessary to place the Tech Article in your cart and follow the checkout routine, just as if you were paying for a part. THERE IS NO CHARGE. After completing the checkout, you can download it onto your computer & have it always if you want.

Here is the o-ring skinny for the fuel injector o-rings.

All LT5 engines have 16 Fuel Injectors and require 32 o-ring seals

93-95 models use the same o-ring, PN 17112222 throughout, top & bottom, both Primary & Secondary Injectors

90~92 models differ only for the Primary Injector, bottom o-ring seal, PN 10067600. This particular o-ring does not install onto the injector. It is located INSIDE the injector housing, about 3/16" down from the top.

Jerrys Gaskets has the o-rings in stock. Both are available in (B) buna and (V) viton. If you use fuel that contains any ethanol, the best choice is Viton

[Corvette95]

I just got the guide downloaded, I will go according to that. I have already ordered and received the orings from you Jerry, I need to check if I have ordered the bottom oil switch on the bottom of the filter housing, I have full access to it right now. Here is a picture of the injectors that are in it now...(primary and secondary)

[Corvette95]

Jerry, also sent you an email needing this vacuum hose under front plenum near the TB..

[Paul Workman]

Originally Posted by Corvette95

I just got the guide downloaded, I will go according to that. I have already ordered and received the orings from you Jerry, I need to check if I have ordered the bottom oil switch on the bottom of the filter housing, I have full access to it right now. Here is a picture of the injectors that are in it now...(primary and secondary)

Originally Posted by Corvette95

So NO orings AT ALL in the secondary injectors?

To be clear, ONLY the 1990 PRIMARY injectors ALSO have a O-ring in the injector bore (in the Injector Housing). Whereas, the secondary injectors are sealed ONLY at the tip - pressed against the boss which is situated in the middle of the secondary runner.

For this reason, when max porting is done on the 90s ONLY, the O-ring boss at the tip of the injector (in the PRIMARY runner) can be removed* entirely as the O-ring at the tip of the PRIMARY injector is redundant. Instead, the O-ring surrounding the injector body at the top of the PRIMARY injector provides the necessary seal.

HOWEVER, IF the motor is to remain stock and not ported, then both the primary and secondary injectors will have O-rings at the tip, AND the primary injectors will also have a second O-ring at the top of the injector body (found in a groove cut into the injector bore about 5mm below the mouth of the bore (as Hans (ccmano) said.

*This is exclusive to the 1990 IHs only: An argument can be made that the air flow in the 90 LT5s can be slightly better in fully ported Injector Housings than later Zs, b/c the obstruction posed by the primary (only) boss can be removed entirely when performing maximum porting.