Okay, I have an LB9 305 in my car, and I'm pretty sure it might be a good time to change my injectors since they were checking out at 10 ohms of resistance (I have to double check that with another ohmmeter, but I think the one I used is quite accurate).

So, if I want to get new injectors, what would you recommend.The car isn't stock, but it's not heavily modified. Currently mods include a Hypertech Thermomaster chip, Edelbrock TES headers/y-pipe, Flo-Pro muffler, no cat, de-screened MAF, Taylor 8mm spiral-core spark wires, K&N Filters and a BBK 67gph fuel pump. I think it has a non-stock cam as well.

Should I get injectors with a higher flow rate? If so, how do I reprogram the computer to let it know it has bigger injectors?Thanks.

 

Time to replace 'em.
What fuel pressure are you running? Push it too high and you'll start taxing the pump. = bigger injectors
If your pulse widths are too high (datalogging) = bigger injectors
If you're running lean and everything else checks out = bigger injectors
If you plan on future mods = bigger injectors
If none of the above = leave it at 19

Datalogging info and the constant to change are located in the stickies at the DIY-Prom forum. Getting into that world though is one helluva mind bender.

 

Currently, I have the stock regulator, but if I go to replace the injectors (which look like the stock pieces - vintage '85), I'd probably put a new adjustable FPR on there and run, something like 55-ish psi (since that seems to give a bit on a power increase, and is about as high as it needs to go).

I really don't plan to put anything big into this 305.

Once I get the cash (which is very hard to amount if crap keeps needing to be replaced), I'm planning on pulling this motor and replace it with a carburated 383.

Should I just go with that now and save myself a ton of hastle, or will carb + winter = no fun?

I looked at that DIY PROM editing and, yeah, that's way too confusing. If I can buy those chips, I'd consider the injectors more (since I do want to rebuild this motor for...something else...*cough*off road dune buggy*cough*)

 

The chips are just EEproms. You can even get them on ebay. It's the datalogging and programming software/hardware that'll start to add up. Even then it's cheaper than buying an off-the-shelf chip and having it changed a couple of times for something that's less than ideal for your application.

55ish psi? Too much. You'll beat the crap outta your injectors. My understanding is that it'll also throw some of the fuel calibrations out in the ECM.

I have a set of 19's from my 88 if you're interested. Cheap.

Carb? Not my world. I'm a big fan of EFI.

 

How will it hurt the pump (I don't understand what it'll do to it).

I know that in the directions for those adjustable FPRs it says to push the psi up to about that range (60 is max).

19 lb/hr is standard, correct?

So then I can still continue to use my Hypertech chip, correct?

 

i have a question for you man since you seem pretty knoledgable of this stuff. what is stock 350 injector size? and if i wanted to increase the size do i have to have a new chip burned or will they work with the stock chip? i am going with the xfi 262 cam and ported tpi with headers and catback. stock heads and 1.5 roller rockers. i think i would like to go with stock but i want to start datalogging later on and dont want to buy injectors twice.

sorry not trying to hijack.

 

stock 19s for 305 tpi rated at 43.5 psi i believe
stock 22s for 350 tpi rated at same psi

either way if your going to change injectors to a diff. size with ur current mods your going to need to toss that hypertech chip in the trash and get into chip burning or have someone else do it for u.

 

Yep.

Since you stated that you're wanting to get into datalogging you should just go ahead and start now with larger injectors. If you don't need the fuel of larger injectors you can change the values in the VE tables (volumetric efficiency (fueling)) to accomodate what your car needs at the moment.

You'll beat your injectors up not your pump. Sorry. Previous post edited.

 

Run some Ford SVO 19 orange tops and you will be fine. Leave the FP alone too. 55 is nuts. I dont know where you heard that from.

 

Agreed...55psi, is way too much.
I put a set of 24lb injectors in my 305. Nice GM LT1's.
Hypertech chip = waste of money.
And why would you pull the screen off your MAF?

 

I didn't pull the screen off the MAF - and I didn't buy the chip either - this was all done before I bought the car.

Nevermind on that high fuel pressure - I misread instructions on BBK's AFPR:

 

Yeah I had a hypertech chip in my car too when I bought it.
Once I swapped everything, I had it tunned.

 

I mean - for the time being, I can leave that chip in there, right?

 

yup thats fine....it really doesn't do a whole lot anyway. I found a HUGE gain when I had it custom tuned though.

 

...I wonder how much that would be to have done...hmm...

 

Well, I swapped my whole top half of my 305.
Then had it tunned. It cost my $100.00 for the injectors brand new.
And they charged me $100.00 to swap them.
Then I paid Just under $200.00 for the tune and the dyno time.
(they had it on the dyno and tunning it for almost 3 hours)
But they only charged me $100 for the tune and $85.00 for the dyno time.
I ran a 14.8 @ 93 mph at the track this year, and that with my sub box and everything left in my car. (plus a passenger)

 

I've been wondering about this too. I have a topend off a 86 TPI vette on my 406 in my 68 C10 and I was wondering about the tuning too. I need to get bigger injectors anyway obviously since I have a 406 and I want to run E85 too, anyway I was wondering if I could just throw in new 42lb injectors in place of the stock ones without tuning them in the mean time while I get a few other things like a laptop for tuning it myself? Will it be safe to do this or will it act all screwy or potentialy damage anything?

 

If you're running injectors from the vette in there now and throw in 42lb'rs without a tune....you'll run extremely rich. Potentially rich enough to wash out your cylinders, thin your oil, and burn up your engine.

 

I C, well what if I were to run off of E85? E85 likes an AFR of about 7:1, is there a way to calculate how much richer 42lb injectors would make my engine vs stock? Kinda sucks cause I believe I have a few bad injectors and I dont wana waste money on stock sized ones when in a month or 2 I'll need to get some bigger ones anyway. Thanks for your help

 

Get a set of used Frod ones; the thin "pencil" body ones are good, or the F0TE part # of the old style.

The ones you want come in 4.6 mod motors; Mustangs, Crown Vics, Lincolns, various trucks, etc. all have them. You can pick up a set for around $40 on eBay.

Like these....

http://cgi.ebay.com/ebaymotors/8-BOS...QQcmdZViewItem

 

hmm, well maybe ill just do that then, thats not expensive and I can have some backup injectors for testing too

 

Ha - used another multimeter, and it told me the original injectors are at 17.8 ohms.

I think I'll still replace them with the ones Viprklr sent me, especially if they're leaking.