at 5000 rpm's my car doesnt pull at all. Could my injectors be to small for all the mods I have? Im planning on adding a set of ported heads would 305 tpi injectors work well? The car should make 180-190 hp after the heads go on.

 

You should really do some more research and tests before making a shot in the dark with injectors. If you can I'd suggest you get an air/fuel ratio guage, or build one, or run your car on any number of diagnostic applications to see if your car is running lean. You can also check your spark plugs and get a general idea if you're rich or lean.

The 17lb injectors I'm selling are from a Z34 Lumina rated at 210hp and 215lbs tq. Even with no cat I wasnt flowing enough air to utilize the fuel. If you went 19lb with mild mods I'd imagine you'd have the same problems I did with the 17lb injectors, unless you had a custom chip made.

 

Are you positive these injectors will work with the engine correctly? I know some deigns are a little different than others. Like you said though, if it works on a car pushing enough air for 210 hp then it should work on my car. I wonder if it would be rich on my car, I suppose I could install a fuel pressure regulator to lean itout a bit, but then again Idont know much about the fuel delivery systems of cars, so I would be going in blindly

 

Well let me put it this way. I can't guarentee anything except that they're from a 3.4 rated by GM at 210hp (from what I read online) and that they're good GM/Rochester Multec style injectors. I tend not to guarentee much because I hate having people return parts that are good, and I hate buying parts that turn out to be bums when I'm expecting a nice piece. For that reason I always give all the negatives and a few positives so the buyer knows what they're getting. The only possible variance I can think of is that the Z34 may have used a different fuel pressure then the Firebird, but I kinda doubt it given GM's habits. They ran ok in my 3.1. They were too much fuel at idle, and would allow it to load up at full throttle. An AFPR might let you back the pressure off a little, but you don't want to go too far as the atomization will start to go south. If you mod your car to pull 210hp they should be about right. For the price you really can't go wrong. Worst case scenario a chip might be needed to narrow the pulse width or somethign to that effect. Given my experiance with these injectors I wouldn't want to go with 19lb injectors, I think they'd be far too much fuel for the car to handle unless its chipped or heavily heavily modded. Also keep in mind my car had the airbox snorkle removed, the cat replaced with a pipe, and nothing else. Cam/heads/porting/exhaust would probably have let it run just fine.

 

First of all what is the Rpm rating of your cam.
If your cam is designed to to produce HP between 3,000 and 5,000 RPM the power curve will fall off after 5,000.
With the computer controls on these cars I cant Imagine making too many radical changes without modifying the computer.
I think porting and polishing the heads and intake so they match will help improve flow which will improve horsepower.
You have to port match the intake runners to the intake ports on the heads and also the exhaust ports to the manifold. Plus make sure the intake gasket doesnt interfere with the flow.
Just throwing on a set of ported and polished heads without port matching everything will help a little but wont give you the maximum HP you could acheive with them.
Also headers {if you can find them) are the big ticket .
You can throw all the fuel and air in the engine you want but its gotta come out.