First a little history. My 1987 z28 came with a 305. The motor was swapped a few years back with a 350. The same fuel injectors were used in the new motor. I've read that the 305 engine came with 19lb injectors and the 350 came from the factory with 22lb injectors. Well, one of my injectors has begun to leak. The dilemma is wheather or not to replace all the injectors with 22lb injectors, or just replace the leaking injector with another 19lb injector. The previous owner told me that the 19lb injectors would be good up to about 350 hp. Of course I'm nowhere near that type of power. I've read that I probably wouldn't notice any power differences by moving to the 22lb injectors. So, do you think it would be worth spending the extra money for a complete set of injectors, or just replace the bad injector?

Thanks for your input.

dave

 

Since you're changing an injector, might as well do them all with a matched set. I'd go with 22#'ers.

 

youll have to change ur chip in your ecm to run 22#s if you want a good set of accel 19lb injectors that are brand new I could sell you a set for 125 shipped to your door. there damn good injectors and they will cost you the same as one injector from dealership.

 

Eric is right, the chip from the 305 was not used, obviously, for the 350. However, you can use 22lb injectors with the 305 chip. The computer thinks you have 19lb injectors... and changes the pulse width acording to what the O2 sensor and other sensors tell it. With 22lb injectors, you'll have more gas flowing through them, when they are opened the same amount of time.

The correct Memcal from the GM dealer is $70, and well worth it. Sometimes you can get away running a 305 chip on the 350, but it be as tuned as properly as with the 350 memcal. Search the boards, and alot of times using the 305 chip made the car run like it had a major problem.

On a 350 with 19lb injectors... you have to boost your fuel pressure to about 58psi to comensate for not having 22lb injectors, and your fuel pump cannot sustain that.

If you don't have that extra gas, you'll be running very very lean.
It's better to run rich than too lean.

Check the classifieds, get some newer 22lb-ers, or get some 24lb Ford SVO Blue top style injectors.

I went with the 24lbSVO because I knew I'd need more fuel with the cam and headers, my car was also stock '87 305. The knock sensor is different from 305-350... might want to check into that aswell.

 

First off, thanks for the replies. So, I could go with the 22lb injectors as long as I change the chip in the ecm. I could also pick up one 19lb injector to replace the one that's leaking. Or I could pick up a complete set from Eric and just replace all the injectors with the new ones.

I've had the 19lb injectors since I've had the car, and I haven't noticed any major problems using them. My car runs hot on summer days when I'm at an idle. I don't think this is caused by the injectors though. The guy that changed the motor put on an adjustable fuel pressure regulator. Are you saying that he had to put that on to compensate for reusing the 19lb injectors from the 305? Or did you mean that the fuel pressure would have to be raised with 19lb injectors only while using the chip for a 350 motor? I definately don't want to overwork my fuel pump.

So, what would be the advantages of running 22lb injectors with the 350 chip as opposed to the way that it's set up now with the 19lb injectors and the 305 chip? From what I've read, there aren't any noticable horsepower gains.

Thanks again for the replies.

dave

 

If you use 19lb injectors.... getting them to flow what would be the stock 22lb... you have to increase the fuel pressure to about 58psi... 18psi more than the stock 41psi for both sets, Via AFPR.

TPIS inside hints says that TPI's like a fuel pressure of 46-50psi... with the required injectors. You can't give the car the more fuel it needs from 19lb injectors.

You might you might not see gains with 22lbers... My guess is you would in higher RPMs. At WOT your air to fuel ratio is ideal at 12:1..... at cruise or idle it's ideal at 14.7. If you have to boost your fuel pressure THAT HIGH with 19lb injectors to achive the 14.7..... I don't think you'll be hitting that 12:1.

You don't need the 350 chip if you aren't having problems now. Atleast I probably would get other things like headers or something before spending the $70 for the chip if my car was acting fine. You CAN use 22lb injectors... with a 305 chip.