Does anyone know ithe size of the TBI moters injectors. I'm tring to find out if the 305 and the 4.3L TBI injectors are the same size? Also what is the pound rating for the 4.3L, 305, 350 and 454 TBI injectors. I've heard the 350 has two different injectors, one for the cop cars and one for other cars, is this so? Thanks, Bobby

 

first site on a google search:

from http://www.cfm-tech.com/gm_tbi_fuel_pressure.htm

 

I'm wanting to know about a 4.3L injector? I know the 350 is more #'s. But will a 4.3L and a 305 swap out.

 

The base pulse width in the chip for the 4.3 is very high compared to the BPW of the 5.0L which would lead me to believe that the 4.3 injectors don't flow as much as the 5.0 but that is just an ASSumption. I have never seen the flow ratings of the 4.3 injectors posted anywhere.

 

According to my BPW calculations, the 4.3 has ~45lb/hr injectors (may also be the infamous 40's). L03s, on the other hand, seem to spec out to have 55lb/hr injectors, not 40. Trucks seem to be 55 or ~62lb/hr. 92-93 Caprice 9C1 injectors spec out to be 68lb/hr (true to their previously theorized rating).

 

Thanks guys. I'd saw a lot of 4.3L TBI's in the junk yards here but no 305 TBI's. Turbo City never E-mailed me back on a matched injector($69), so I guess I'll go to Auto Zone($65). The drivers side is the only one thats bad. I wanted to send my good injector to Turbo City and let them test it and get me a matched one to go with it. I figured it be worth the extra $5+shipping to have a matched set, but after several tries to contact them I've got no responce. Thanks, Bobby

 

good *** almighty dont get the autozone stuff... its garbage. My car ran like pure **** with them. They drip alot and the spray pattern isnt all that good. Even though my engine ran richer with the delphi injectors i have now it still got much better fuel economy and had so much more power. Its like the AC Delco commercials. Pay a little more now or pay more again later.

 

Done got the Auto Zone($65) injector. It has a one year warranty. It looked alot different, you know the round ring like filter on the bottom of the injector, well on the new one the whole bottom is a filter. Also where it sprays the fuel is up in a hole now, instead of being right at the tip. But it has a lot better spray pattern than the other injector(could be that the other one is just old). Thanks, Bobby

 

ive come to the same conlusion myself. I think that after prolonged use the tbi injectors can gum up inside and not work right or maybe the pintle wears irregularly. My stock ones always sprayed like crap. Really bad pattern. I convinced myself after a while that it was probably normal. The autozones where better but not by much. I was totally blown away by the delphi (gm) ones with my holley. The spray pattern was what i always thaught it should look like. The engine ran like a damn rolls-royce after the tbi swap. The idle didnt change at all but before it always shaked like hell when i revved it and the exaust really sounded bad. My dad said it always sounded like a motor boat inside. Afterward, it revved as smooth as glass. No vibrations at all and the exaust note was much quiter. All that just from the injectors. The A/F ratios and BLMs hit rock bottom but it still ran much better. Was rich before but now its really rich. Will be fixing that shortly, though.

On a side note, maybe they improved them. The ones i got looked like the regular run of the mill gm injectors. Not what you describe. As for the hitting the sides thing, the ones i had did that as well.

 

how much and what is the part number for the delphi injectors? Is everyone complaining about running rich with those or their old injectors? dimented24x7, about how much of a fuel mileage increase did you see with the new injectors and was the power increase all that noticable?? I never knew so much to be had just by changing the injectors.....guess it would be a good idea to get mine done on my 140,xxx mile car. Should I upgrade to 55's instead of the 40's if I plan on doing a cam swap and a few other minor mods later on? Thanks for any info!
Lc

 

the holley delphis are propriatary to holley tbis. Theyre about half the size of a standard tbi injector. There is alot to be gained if the injectors you have are garbage, as was in my case. I noticed alot of buildup in the fuel system because the previous owner didnt take much care of things, probably due to crappy gas. After all, it was the cheapest running V8 thirdgen i could find that wasnt rusted out. As for the injectors, if theres nothing really wrong with them to begin with, you wont notice any improvement. But in my case, there was alot of improvement in part throttle performance and a 10 mpg increase in fuel economy. I also noticed that the oil stays alot cleaner between change intervals. Most of this is probably due to the fact that i just had a bad luck and got dumpy injectors. Even though the A/F ratios went down, the improvement in fuel distribution made all the difference. I suspect that yours are probably still good, though. If the spray pattern is still a uniform cone and there are no drips, i wouldnt worry too much about changing them out.

 

Ah, so it's just whether your fuel system has been taken care of or not. Makes sense. My injectors still spray pretty uniformly, nice cone and everything....as far as I know. Of course the only knowledge of TBIs I have is, well from my own car. But part throttle and WOT are really ok, no sputtering or anything. Maybe when I get some time I'll just have them flow checked and see if they are both still fine. Thanks for the info.
Lc

 

Can somone explain to me exactly what the cone/distribution of the mixture is supposed to look like?

I'm not getting enough power out of my 350. Ithe injectors spray looked ok to me, but I had no idea what to look fors, used to carbs dump/squirt look hehe

Anyways should it be a perfect cone? like a shower.. is it ok if the cone is "missing some spots"