Hey all,

I'm building my new engine and went to install my new 36lb injectors I got from Southbay into my holley stealthram. I used this intake on my old engine with factory injectors and everything fit up fine. When I go to set the fuel rail down on them, the injectors seem to be too long. Even if I press down, I dont feel any more movement and the holes in the fuel rail are an 1/8" to a 1/4" too hight to align with the holes in the manifold. I just want to make sure I'm not missing something obvious here before I reach out to southbay tomorrow, or maybe they will see this and respond before I do. I know they are pretty active on the forum.



Factory injectors

New Southbay injector

You can see the difference. Camera aligned with top of injectors, first one is oe, three beyond are the new Southbay ones.

If you look in the hole you can see where the screw wanted to go vs the actual threaded hole.

 

Their site says contact if you have a aftermarket base, did you reach out to them to see if the ones without the pressed on adapters work ?

 

I did not, I guess I focused on the part that said, "Plug and Play: These injectors are crafted to directly replace the stock Rochester/Multec TPI injectors without any need for modifications, milling, or spacers."

Hy factory injectors fit and functioned perfectly in the HSR before, so I thought that meant it took the same injectors...

Sounds like I need to give them a call in the morning... Unless someone else has any experiences that would apply...

 

Spoke with Southbay this morning...

PSA: It sounds like the TPI injectors with the perminant adaptor are only needed for factory intakes. Make sure to check in with Sputhbay if you are using any other intake, however similar, or what injectors ypu were using before. Specifically, the HSR requires the standard length injectors without the adaptor. There is not a separate PN I could find on the site, so make sure you check with them before placing your order.

Luckily, they are allowing me to exchange the ones I bought with the correct ones!

 

Good news.

Yeah Southbay has good customer service.

 

Got the new injectors in. There is now an 1/8th inch of play, but once the system pressurizes it will push the injectors all the way down, and as long as the upper o-ring is still above the chamfer in the fuel rail it should seal and we should be good!

You can see in the pictures one injector is all the way up and the other down.

 

sorry for the inconvenience. When we designed those adapters and orings it was specifically for stock set ups because they are approx and oring shorter than stock. To be honest it's on all of our listings. Anyway, I hope you installed them into the intake manifold first and then the fuel rail. If you have any problems please give us a call at the shop tomorrow. If you have the injectors with the adapter with the aftermarket intake we'll be more than happy to exchange them for you.

 

I've been speaking to you in parallel. The Ijectors I initially bought are alredy on there way, will be back to you tomorrow. Thanks again for that. All's well that ends well.

I see the message on the listing now, I missed it. It may be clearer if you add another listing on your site calling out the specific efi sbc intakes you know the shorter injectors to work with... just an idea, since I only saw one option, so I didn't think much more about it. Or, clearly read the whole description, lol...

 

 

Hey SouthBay, so I have finished my build installed the injectors, and have fired up my new engine!

Now I'm working on tuning but I'm unable to find the injector pulse width correction (offsets) for these injectors. They're marked 0280155830. Do you have this info for these injectors?

I'm told the values below may be close, and I'll use them unless I'm able to find something more spacific...

 

Hey........unfortunately we do not

 

The 831's I bought from Southbay last year work well with the known-accurate offsets I have on the 759's from Ford Motorsport's datasheet.

When I was researching for offsets on the 831's, I was finding that most of the Bosch-III's have similar voltage offsets to eachother (for the ones I could find). And I think if you get within a few microseconds of accuracy, that's typically good enough. The rest can be tuned out with the VE and other fueling table changes.

So I think your 830's will do ok with the 759 offsets you're showing in your screen capture.

 

My attention was just brought to another very informative thread on TGO: Anyone have problems running Bosch III injectors with Edelbrock manifold? - Third Generation F-Body Message Boards

The aluminum adapters were clearly too long to fit. The standard B3 injectors are currently installed and fit, but there is verry little engagement beyond the chamfer in the fuel rail. It looks like based on the thread above, I can achieve a mid installation length by adding a second o-ring to the plastic groove above the normal o-ring groove. I'll have to get a pack and give that a try when I get a chance.

Keep in mind it is not necessarily the o-rings that determine the positioning of the injector, but actually the seats at the bottom. the standard B3 injector has the chamfered portion on the bottom of the injector, that gets pressed against the manifold when the fuel rails pressurize. BUT, if you add the second o-ring, it seems the o-ring acts as the seat hopefully better centering the injector between the fuel rail and intake.

 

Just an FYI....that is not the way you measure injectors for fitment. They need to be measure from oring to oring

 

I have noticed others do measure that way, but at least in my engine, that is not how the injector physically fits. I measured from the surface that seats against the intake to the top o-ring that needs to fit into the fuel rail far enough to seal properly and reliably. As you could see the injectors with the aluminum spacer, physically could not fit. The short standard injectors without do fit, but the top o-ring only engages into the fuel rail just barely past the chamfer. That's why if I can try the double o-ring setup, to produce an intermediate length I may end up with better more reliable o-ring engagement.

Question for those have done the double o-ring trick. Is that just another standard o'ring as used below in the primary sealing location just stretched a little larger?

 

yes it acts as a stop and a secondary seal to prevent a vacuum leak.
@southbay what’s recommended on the stealth ram with Bosch 3 injectors. Obviously no press adapters but 2 or 1 o-rings on the bottom?

 

So we designed the adapters and the square oring many years ago. Its not that the injector doesn't fit into the intake with the adapter. The square oring does go into the intake. The reason the adapter does not fit further into the intake is because you need additional height / length with the bosch lll injectors because they are shorter than stock. If you try to push them further into the intake you will be defeating the purpose as they need to sit the way the double orings do.The adapters and the double orings server the same purpose. The second oring does sit on the outside of the intake to give it the length needed just as the adapter does.
The adapters and square orings are Only used for stock intake and fuel rail.
They are not to be used with an aftermarket intake manifold of any kind as the injectors without the adapters are the proper length. If you were to use the adapters with an aftermarket intake they will sit too far into the rail. I hope this helps:

1) Adapters with stock intake
2)Standard length injectors without adapters for aftermarket intake

Let me know if you have any other questions