Questions about working on a 3.4

[MrBrownPants]

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 don’t know a whole lot about engines really, but I know enough to get around one.

You see my Firebird was my first car, it’s 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: http://www.ls1.com/forums/f68/some-i...hv-motor-4706/.

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 wouldn’t be possible. I have looked close at those two intakes, well as close as you can on the internet, and I just can’t 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 don’t know anything about the grand am so I’m guessing by research that they are underneath the plenum and connect to the lower intake. So I’m 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 can’t find any place with them. Heck, I don’t even know what #19, #20 even means. Also ‘Forced firebird’ recommend using a standalone ECM, but I really don’t 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. ‘koolchriscamaro’ said that using ’91 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 don’t 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,
Bradley

[caffeine]

It's best to swap the pistons, heads, and both intakes from an 00+ 3400 car or even better pistons for a 3400 and heads/intakes from an 05-07 3500 car. The stock 3.4 PCM can be tuned with Tunercats.

You cannot only swap the intakes. If you swap heads without swapping pistons you will end up with between 11.5-12.x:1 compression depending on the heads and head gaskets used.

[MrBrownPants]

Right right, I would definitely be swapping out everything at once, not just one or the other.

And I have heard that it is better to use a 3500 but I have also heard that it is exceedingly difficult to do it because with the 3500 intake on, there is no clearance at the cowl. The 3500 is taller than the 3400, and the 3400 is a tight fit as is.

My main question about the intake is whether or not all of the sensors and hoses from the 3.4 intake will be be a direct transition to the 3400 intake.

[caffeine]

Some sensors will swap over; you may end up replacing your two coolant temp sensors (one for gauge and one for PCM) with a single 3-wire CTS, the MAP sensor on a 3400 is exactly the same, and I'm not certain about the IAC and TPS but if those don't interchange it's not too difficult to change the wiring because the wires are more or less the same.

You could always use 3500 heads/lower intake with a 3400 upper if you wanted.

[MrBrownPants]

Ok, that's good to know. Aren't those sensors you mentioned on the throttle body? Speaking of which, what throttle body would I use?

If I were to use 3500 lower intake and heads with 3500 upper intake and pistons, would my pushrods need to be changed? Or could I still use the ones from a '91 3.1 cavalier as suggested?

[caffeine]

Questions about working on a 3.4

Pushrods are always different with aluminum heads. You cannot use 3500 pistons in a 3.4 because of the difference in bore size, but you can use 3400 pistons and 3500 heads.

I'm not sure if the stock TB could be reused but I'm pretty sure the 3400 TB is bigger anyway and probably better to use.

[MrBrownPants]

Crap, that's what I mean to say. I meant to say: "If I were to use 3500 lower intake and heads with *3400* upper intake and pistons, would my pushrods need to be changed? Or could I still use the ones from a '91 3.1 cavalier as suggested?" I apologize

Alright, then, I would probably have to test it and see when to time comes, unless anyone else knows for sure.

[caffeine]

Questions about working on a 3.4

The pushrods are the same between 3500s and 3400s if that answers your question

[MrBrownPants]

Well I read on the fifth page of the forum I posted that 3400 pushrods should not be used.

[caffeine]

But if 3.1 pushrods work for 3400 heads then they will work the same for 3500 heads

[MrBrownPants]

Ok! That's exactly what I was wondering and trying to ask.
So let me get this strait, for best results use; 3500 LIM, and heads, 3400 UIM, Pistons, and TB, and apparently 3.1 cav pushrods. Correct?

So does this mean that the 3500 LIM is the same as far as sensor placement and such as the 3400 LIM? Sensors and hoses are my main concern because I think anything is better what is on there now.

[caffeine]

Questions about working on a 3.4

The only sensor that goes in the LIM is the coolant temp sensor. The 3500 doesn't have a CTS boss drilled/tapped like the 3400 LIM but on my engine I removed the one heater core outlet from the LIM, tapped it for 1/2" NPT (hole was already the perfect size), and used a 1/2" - 3/8" NPT adapter for the CTS. Alternatively you can also drill/tap the CTS location in the 3500 head for 3/8" NPT.

You will need to delete above mentioned heater core hose outlet anyway since on the RWD engines you have one on the water pump and the other will come out the rear of the LIM.

If it doesn't make sense now then it will when the parts are in hand.

[bszopi]

You will need to use a FWD throttle body, as the mounting holes between a FWD and RWD TB are in opposite corners. And you won't be able to use a 3500 TB as it will be a drive-by-wire unit. So you'll need to go with a stock 3100/3400 TB (52 and 56mm respectively), an LX5 TB with adapter (62 or 65mm, can't remember for sure), or an aftermarket TB for TEC.

Brad
via Moto X

[MrBrownPants]

Alright caffeine, so I will need to/can remove the heater core from the 3500 LIM, since I don't need that one anyways, then drill and tap that to 1/2" and put a 3/8'' adapter on it so that the coolant temp sensor can go there, correct?

And Brad, (my name is Brad too, how ironic,) would the 3.4 sensors that are on the TB go onto the 3400 TB, such as IAC and TPS? I think those are on the TB. Ok, I am not that good at the sensor name game, so I'm just going to show pictures. Haha! So looking at my throttle body, all these sensors are going to fit on a 3400 Tb?

Now, to double check, all of these sensors that are on my 3.4 upper intake are going to fit correctly somewhere on the 3400 upper, right?

[bszopi]

Yes, the TB sensors should swap over, although theres a good chance whatever TB you end up with will come with all of the sensors. GM IAC and TPS are fairly universal.

Brad
via Moto X