I am 99.99% sure I will have a deal worked out to get a 86 fiero gt tomorrow but it has a bad engine
I would like to put a 3.4 engine in it but not sure how the auto trany will handle it

Also never taken a engine out of a fiero any thing I should watch or look out for

quote Originally posted by ANTEC900: I am 99.99% sure I will have a deal worked out to get a 86 fiero gt tomorrow but it has a bad engine I would like to put a 3.4 engine in it but not sure how the auto trany will handle it

I've an `86 Fiero GT as well, and the auto transmission in it has handled its 3.4L engine swap just fine.

..The 3 speed automatic that comes stock in the fiero is a GREAT TRANSMISSION,,this was the base automatic in a gazillion G.M cars ,it is more reliable than the 4 speed comonlly swaped into Fiero,s,,it has gotten a bad rap because it has only 3 speed .& does not deliver the MPG the 4 speed does
.. these transmissions are neglected ,recieve no maintenence,, so change fluid and filter
.. you can change the chain drive in these transmissions for better gas milage & thier are a few performance upgrades ,but it is designed to last 30 years

quote Originally posted by uhlanstan: ..The 3 speed automatic that comes stock in the fiero is a GREAT TRANSMISSION,,this was the base automatic in a gazillion G.M cars ,it is more reliable than the 4 speed comonlly swaped into Fiero,s,,it has gotten a bad rap because it has only 3 speed .& does not deliver the MPG the 4 speed does .. these transmissions are neglected ,recieve no maintenence,, so change fluid and filter .. you can change the chain drive in these transmissions for better gas milage & thier are a few performance upgrades ,but it is designed to last 30 years

Good to know

Also what all will I need to change on the 3.4 for it to fit where the 2.8 was I know I need to move the starter

quote Originally posted by ANTEC900: Also what all will I need to change on the 3.4 for it to fit where the 2.8 was I know I need to move the starter

I've referenced below a succinct write-up on what you'll need for a 3.4L engine swap into your Fiero: http://fiero34swap.eleventenths.org

Titled, "Fiero 3.4L F-Body Engine Conversion," that article authored by fellow PFF member, crazyd, indexes its subject matter into 22 sections:

1. Getting Started
   
2. 3.4 Engine Choices
   
3. Gaskets
   
4. Mounting the 3.4 Engine On Its Stand
   
5. Oil Filter Adapter
   
6. Mounting the Flywheel/Flexplate
   
7. Relocating the Starter: Drilling the Holes
   
8. Tapping the Starter Holes and Mounting the Starter
   
9. Exhaust Manifolds
   
10. Bellhousing
    
11. Block Chop
    
12. Oil Pan
    
13. Timing Cover
    
14. Cleaning Gasket Surfaces
    
15. Water Pump
    
16. Harmonic Balancer
    
17. Accessory Transfer
    
18. Oil Pressure Sender and A/C Compressor
    
19. Clutch
    
20. Mounts
    
21. Installing the Engine Back On the Cradle
    
22. Setting the Ignition Timing

Since you started out this thread asking about the TH-125 automatic transmission and the 3.4L engine swap, I'd think that in particular, you'll benefit from Section 11, "Block Chop." However, I encourage you to read the other sections too, because I relied on an earlier version of that write-up for my own 3.4L engine swap into what is an automatic-equipped `86 Fiero GT as well.

Good luck to you, ANTEC900, with your own 3.4L engine swap project in your automatic-equipped `86 Fiero GT.

quote Originally posted by uhlanstan: ..The 3 speed automatic that comes stock in the fiero is a GREAT TRANSMISSION,,this was the base automatic in a gazillion G.M cars ,it is more reliable than the 4 speed comonlly swaped into Fiero,s,,it has gotten a bad rap because it has only 3 speed .& does not deliver the MPG the 4 speed does .. these transmissions are neglected ,recieve no maintenence,, so change fluid and filter .. you can change the chain drive in these transmissions for better gas milage & thier are a few performance upgrades ,but it is designed to last 30 years

I totally agree - the two vehicles i've had with TH125's shifted great even after 20 years and 200,000 miles, but definitely keep up with fluid & filter changes. The 93 Beretta (3.1 & TH125) I had with 200,000 miles when I got it was shifting poorly, lots of slipping. Shifted absolutely perfect with a fresh filter and fluid. Likewise, the 89 Beretta (2.8 & TH125) had a hard shift between 1-2 when I got it with 79,000 miles but fresh fluid and filter smoothed it out.

The only trouble spot with the TH125 is the lockup solenoid, which isn't too difficult to replace and pretty cheap.