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Questions about working on a 3.4

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  1. #1
    Junior Member
    Join Date
    Feb 2014

    1994 3.4 Firebird

    Questions about working on a 3.4

    Hello everyone, my name is Bradley and I have a completely stock 1994 Pontiac Firebird 3.4. I am 22, still in college, and about to get married, so money and time is not something I have right now. Anything I do to this car would be done next year around this time, maybe sooner. Now I donít know a whole lot about engines really, but I know enough to get around one.
    You see my Firebird was my first car, itís actually the only car I have ever owned and I love that car. Right now this car is past 185,000 miles and I think she is getting tired. So with my love of that car I decided that I needed to do some upgrading on her to bring her some glory. I did some research and looked around and read a lot of things and found that the 3.4 is pretty mediocre, well pathetic almost. But then I read this post:
    This post gave me hope that there is a chance that this engine is worth something; it was just terribly designed by GM. So I looked further into what was talked about; mating a FWD 3400 series intake and heads to my 3.4 RWD.
    So here are my questions about all of this:
    1: Is the swap on the 3400 both an upper and a lower swap? Because it looks like to me, the novice, that if it were just a plenum swap it wouldnít be possible. I have looked close at those two intakes, well as close as you can on the internet, and I just canít see how it would work. What about all of the sensors and hoses that are attached directly to the 3.4 and in between the two main ports? It looks like there are far more sensors and hoses attached to the 3.4 than there is the 3400, so it looks like there is no room for all of them.
    2: While we are still at the intake, what about these fuel rails? I donít know anything about the grand am so Iím guessing by research that they are underneath the plenum and connect to the lower intake. So Iím guessing that the fuel lines that are used in the 3.4 will go into the fuel rails then? So this means you have to swap out your lower intake, right? Also, what I have gathered is that I will need larger Grand am Fuel injectors, preferably #20 or above, but where can I get those? I canít find any place with them. Heck, I donít even know what #19, #20 even means. Also ĎForced firebirdí recommend using a standalone ECM, but I really donít even know what that is. And by reading I take it I will need to get the 3400 intake gaskets to make to the 3.4 block.
    3: Now the heads seem like a world of problems, kinda. From what I understood, I would need to use 3400 heads with the corresponding, heavy duty gaskets. And apparently the push rods and pistons need to be changed as well. It seems that I need to use 3400 pistons to be used correctly with the 3400 heads. Ďkoolchriscamaroí said that using í91 cavalier 3.1 pushrods with those same intake and exhaust valves would work. Also, I have gathered that I will need spark plugs for the grand am and that 3.4 headers will work if I elongate the bolt holes.
    4: What about a throttle body? Nothing is mentioned whether or not the 3.4 throttle body will work.
    With all this information, this is what I have come with in short. I still need those other questions answered though.

    What I will need:
    1999+ Grand Am GT 3400 upper intake plenum and lower intake with gaskets and fuel rail as well as injectors. Also, heads with the gaskets - pistons - and sparkplugs.
    1991 cavalier 3.1 pushrods and intake & exhaust valves.
    If I choose to cam it out, I would need to put a 250+ cam on it so as not to have to change my computer tune, although I might do that anyways if anyone can.
    Is there anything I am missing? Like I said, I am not an expert. I donít know a lot about engines and all of this work will definitely not be done by me. I just want to make this old car nice again, and make that v6 fun to drive. I appreciate any information anyone can give.
    Thank you all for reading and responding,

  2. #2
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