Alright,

Just recently one of my injectors completely crapped out on me, and this has urged me to go on and buy a new complete set. I am still running the stock injectors which has seen 92k miles. The engine has under 3k on it.

I have a fairly beefed up 350, and from what Ive heard the stock injectors are 21 lbs, I would kind of like to go a step bigger, ONLY IF it wont cause problems with my computer.

I do have a custom burned prom based on all the car's mods, but I need to know if going to something like 24 lb injectors would cause any problems (Performance Or Drivability)

Will the computer/custom PROM be able to work with the bigger injectors or will the PROM need to be re-done?

 

I believe that the factory injectors are 22#/hr (well I know that they are, I have an '87 350 and I have been "burning" my own Eproms). I highly recommend buying the Frod racing 24 #/hr injectors. The ECM has about 16% correction in it, while the flow rates are 9% different. While you are at this, buy an AFPR (not the Holley one, apparently they are crap now) and install it along with the new injectors.

With a built up 350, you probably need the 24s. You should be OK. But make sure you buy the Ford Racing injectors. I have and many one this board have been running the Ford Racing (formally SVO) injectors. I been using my set for 7 or 8 years.

 

I know in the prom there is a constant for injector flow rate. Whether this really affects the prom dramatically really makes me wonder. I would think if the value was changed to the correct constant it would proabaly be a good thing but proabaly not %100 necessary.

 

You should be fine for idle and cruising but wide open throttle will be rich.

 

Slightly rich. He has MAF. It's more forgiving than SD.

 

It will idle rich while in open loop, and improve when the loop closes.

 

Tell that to the guy with an '88 GTA who swapped in 24lbs LT1 injectors. It ran ok on the street, but it belched black smoke out the tailpipe on the dyno. That was a MAF setup.

 

Interesting. On my 88 MAF I went from 19's to 24's and didn't have any problems with black smoke. Of course that's a big jump and it didn't run the best until I changed the prom.
Even on my 92 SD where I went from 22's to 24's I didn't have problems. Scanning between programmed proms only showed a BLM difference of 3 points and the INT's had an 8 point difference.

 

FWIW, here's my experience:

My (stock, 22#) injectors took a dump several years ago, so I replaced 'em w/ 24 lb units. Seems to run perfectly fine during normal operation (no apparent loss of MPG or driveability), but I wouldn't be at all surprised to learn that it's costing me a bit of power at WOT.

I've been meaning to get that corrected in the PROM, but wanted to wait until I had more engine mods to make it "worth the effort", & lately everything I've been doing has been suspension-related!

Bottom line - tuning should be done for that change, but it will likely run "OK" if you don't. (AKA, do as I say, not as I've done...)

 

So.....Even with a modified engine to make use of the extra fuel being added, the bigger injectors can still cause problems?

 

If you have a slightly modded engine, then you want the 24s. If the engine needs abit of more fuel at WOT (because it is modded), then the 24s are the right sized injector for you,, and no new chip should be necessary.