Hey all... Pulled my pod apart today, and MUCH to my dismay, there are NO part numbers on my injectors! (WTF?!) The TBI unit came from an early/mid 90's 454 truck. If it makes a difference, the insulators on the injectors are orange (maybe they all are!). The stock pressure seems to be about 30psi (I think my pump can't put out enough at this point, so I'm swapping it out later today). Anyone know how to tell what they are? 65lb? 80? 90?

Earlier 454 trucks used 12 PSI and large injectors, such as 80 or 90 PPH. Mine are 90 pounders from a 12 PSI 454 89' burban. The later trucks (like what you got, sounds like) running 30 PSI used a much smaller injector. If I remember correctly, It's somewhere along the lines of the size of a 305 or V6 injector when used @ 12 PSI and is not very useful for performance.

You sure there are absolutely no numbers engraved on the top? Sometimes they are very hard to see. I've never seen a TBI injector without some form of marking.

I'm not running them at 12 - they're at about 20 right now (and WERE at 25+ ... I think the pump is dropping dead at the higher pressure, or the in tank sender to line hose has come loose).

Yeah, I was amazed there were no part numbers on the top of them as you'd normally see, but after doing some reading here, it seems that if someone glass beads the unit (as it appears they'd done - WAY too clean!) it'll knock the numbers off.... Grrrrrr!!!!!

I just need to know what the stock flow at (30lbs?) was so I can get my BPW right.
I've got a WBo2, so worse comes to worst I'll just fudge the numbers and adjust as required.

Another update...

According to a guy over at fullsizechevy.com, the #17113080 is a 90lb/hr unit, running at 23psi, used in 94 & 95.

The others was a #17112560, used from 91-93, and ran 12.5psi.

So, looks like I have the 90's, based on the (initial! Argh) pressure I was getting.

Don't suppose you have the p/n's from your injectors to correlate the above info?

Give me your TBI# and I will see what i can do to tell you exactly what you have. More than likely you have 90lb injectors based on the 17113080 number. This is ACDelco part# 217-348 and only found in 94-95 7.4L trucks.

If i know the exact year your TBI came from then i can tell you what you have. Typically, most 94 and newer 7.4L TBI (including marine units) used a 45lb injector running at 29-32psi. This was done to reduce vapor lock at higher ambient temps and "possibly" help with a more stable fuel flow from the injector.

Very few 94 and newer 7.4L TBI's came with 90lb injectors.

Hey, that'd be great...

#'s off the TBI itself are:
17093049
D 0813 KJP

Thanks!

If your injectors are original to this TBI unit then these are 80lb injectors. This unit came off a 1993 C, K pickup with a 7.4L and A.T. transmission. 1990-1993 7.4L TBI trucks had 80lb injectors. 1989 and older had 90lb injectors.

Hope this helps.

Awesome! Thanks!

So, that's 80lbs based on them running at 23psi right?
Still beats the crappy spraying 65's from the cop car I had in there (that's where my engine came from in the first place).

Well, typical 90-93 trucks ran at ~13psi.

Your fuel pressure needs to be set according to the exact flow rate of your injectors, horsepower of your motor, etc. This is where the "tuning" gets serious, lol.

Do you still have those other injectors? If so I may take those off your hands if you're interested in selling those.

Oh, OK. I had just put the whole pod from the 454 onto my smaller TBI and fueled it up - and it initially came up to about 25lbs. Just assumed it was 'the one' that ran at 23.

I've got a Vortec headed 350, with a little less than the 'zz4' cam in it, headers, bla bla bla... desktop dyno says it should be about 350HP if I can get enough air into it.

At that level, from what I've read, I need about 110lb's of fuel (to make up for AE).

I'll let you know on the 65's I've got after I get these all straight.

Sounds about right!

Ummm.. which one was I right on?

The fuel requirements, or that I should be running these at ~25lbs (vs. 12.5)?