I have a 1990 Firebird with a blown v6, automatic

I also have a 89 Formula with a 305 TPI, 5-speed

I also have a 355 that I want to put in the 90 bird.

My question is besides motor mounts, what has to be changed, and is there some diagram to know where to put the new mounts?

What about the wiring harness, I am going to go carb on the 355 unless the TPI system will work from the 305 to the 350 without being to restrictive.

Does anything have to be done to the dash harness, to use the guage cluster from my formula?

Also I am going to swap to the 5speed tranny, so what has to be done for electrical there?

Thanks in advance for anyone who replys,

Joel

 

you will need to move the motor mounts, you will also need a V8 radiator

also, a brake line needs to be moved

TPI shouldnt be too restrictive, just make sure you put in the correct 350 PROM

 

Move brake lines?!? Never had to touch mine when I did this swap.
The main harness from the junction near the master cylinder will hook right up to the 355. The tach will not read correctly however. The reverse light switch routes with the pcm harness with the 5-speeds. You will need that part of the harness from the donor car to make your harness for that. You should find the connector for the body side of it just behind the right side lower dash panel about where the passenger's left knee would be. When I did my adaptor harness for the 4-speed I just used the wires that went to the switch from that connector to make the harness. You should be able to just use the whole section of harness and route it as the factory did thru the right side kick panel.

 

I have a radiator, where do I get the 350 PROM??

This 355 is an older block if that means anything.

Why wont the tach read correctly? Say I was to pull my cluster and computer out of the Formula and put in in here?

 

I forgot one thing about the TPI, If I went with that would i have to get a bigger throttle body, and injectors, and would I have to do anything to the heads?

Because I dont have the money to do all that, and I already have an intake and carb.


Thanks

 

For V6, brake line runs across the front of the crossmember, engine mounts are towards the back. For V8, engine mounts are towards the front of the crossmember, brake line runs across the back.

If you didn't move the brake line, your engine mounts are right on top of it. Generally not considered a good thing to have a brake line smashed flat.

The 305 TPI will work as well on your 355 as the factory system did. They're the same, flow-wise. The factory used higher flow injectors, different PROM, and different knock sensor/module. Unless the 355 has some kind of wild cam in it, the TPI will work fine.

Of course, the factory TPI choked a 305, so porting the plenum and base are a good idea. Larger TB isn't a bad idea, either. As is an adjustable fuel pressure regulator (which can allow you to get away with the smaller 19 lb 305 injectors on a 355). But, it will run as-is.

 

Thanks for the information on the brake line.

What would you suggest me to go with, carb, or TPI, I am on a low budget, but i have everything from the 305.

Could someone please answer my guestion about the tach problem?? Thanks

 

Unless you have everything you'll need for the carb change-over, it will be less expensive to go with the TPI.

The 5-speed electricals shouldn't be a problem (although I'm not completely sure about digital speedo issues). That harness should be part of the engine harness, which you're going to change over, anyway.

I'm not familiar enough with Firebirds to say anything more about the cluster, compatibility, etc., but I do know that V6 and V8 tachs are different.

 

i have an intake and carb already, but i know to use the TPI ill have to get a knock sensor and the 350 PROM and im not sure how much all of that is...

 

All I can tell you is I didn't have to touch my front lines at all and no my mounts are NOT on top of the line. I would think it would be pretty obvious if there were. Maybe your later year has them different but mine were left in their original locations right up to when I redid them when I installed the linelock.

 

I'm curious, why don't you want to put the 355 in your Formula 350? You could then stuff the regular 350 into your V6..

Todd

 

Yours is earlier than '82?

 

No. Mine is a one owner, me, 87 originally equipped with a 2.8 5spd. All changes to this car were done after it turned 200k miles. All repairs ever done to this car were done by myself. At no time when I swapped over to the 400 did I ever have to touch any brake related parts. The only headache I ran into was when I put an old M22 Muncie from my 68 Camaro that I still had in my cellar in with the 400 as all shift linkage, mounts, etc had to be fabricated.

 

because the formula is rotting away, and its become to lengthy to try and save it...

 

Thats not what it looks like now but at one time, here it is a few weeks ago...before it was all welded in..