Fiero Swap

[jester223]

Looking to find out if a 3400 LA1 long block is interchangeable with my stock 2.8. I was looking to do the 3.4 L32 swap from an F body but i wasn't looking forward to rebuilding a high mileage motor, on top of the fact that 3400's are EVERYWHERE! I was hoping to use pretty much a stock intake and fuel setup and preferably make it look as stock as possible. Just trying to get a hold on what I'd need to go about doing so. Any and all help is appreciated.

[caffeine]

I would recommend ditching the stock intake and accessories and going with a full 3400 swap. Use a 7730 ECM (easy easy wiring involved and well documented). You will never need to worry about timing the distributor properly and end up with a much better flowing intake.

[caffeine]

Also it's pretty cheap to make braided fuel lines for the swap since they're so short. If you want even cheaper you can use rubber line and Dorman makes a quick-disconnect to rubber hose clamp adapter.

[ericjon262]

please don't swap the fiero heads onto a 3400!

[caffeine]

Seems to me that swapping Fiero heads onto a 3400 would significantly decrease compression as well. Bad for performance.

[jester223]

fiero swap

would i still be using the fiero harness? as far as fuel and coolant delivery, would i still be using stock fiero equipment? and are all the sensors and such the same? how about mounting? and accessories?

[ericjon262]

mounts are the same if you use the fiero timing cover and accessory drive. you will need to modify the harness or have someone make one, I've heard phonedawgs on PFF makes real nice harnesses. fuel pump should probably be ok, and the sensors use the same voltages and outputs, but you'll need to update to a 7730 ecm, or a PCM.

[caffeine]

When I swapped my 3500 (slightly more involved), I used the stock Fiero harness and just repinned the ECM connectors and changed the pigtails for the IAC, TPS, O2 sensor, and maybe something else too. I deleted EGR and just left the stock EVAP hooked up to a vacuum line. Fan switch pigtail became the knock sensor pigtail (you will need a 7730-compatible knock sensor as well).

I can give you part numbers for coolant hoses. I happened to have some lying around already that fit almost perfectly, and I made my own engine bay coolant filler with about $10 worth of parts.

For fuel lines I would suggest just building some braided lines, it's pretty easy to find part numbers for fittings that will both plug into the 3400 rail and into the stock Fiero fuel lines. I'm still running the stock Fiero fuel pump an it's had no problem supplying fuel for a 75 hp shot of nitrous as well.

I think there are a few ppl who can sell you tunes for a stock 3400 as well.

[ericjon262]

post some pictures of your car, and give us a little more info about your goals.

[caffeine]

I want to note that I've seen one 3400 swap on the local Fiero forum which used the stock dogbone mount AND kept the 3400 timing cover/water pump. He modified a A/C bracket from some car to fit a Fiero alternator. I could dig up the details if necessary.

With that arrangement you get the best of both worlds; a nice compact serpentine belt with no squeaking, and you can still use the stock dogbone mount without needing to make one. Also, no decklid cutting was necessary.

[caffeine]

Oh and if running a 7730, getting a 3-wire CTS is probably necessary which will mean another pigtail change. It's nice though to only have one coolant sensor for the gauge and the computer.

[jester223]

and just on a side note... how do those motors hold up against boost? i'm definitely interested in a turbo setup

[caffeine]

There are several boosted 3400 on this forum I think. If you are able to do the extra work for a 3500 swap though, they seem to have a stronger bottom end and better top end.

[Bridgetown]

I've heard phonedawgs on PFF makes real nice harnesses. but you'll need to update to a 7730 ecm, or a PCM.

You heard right. I have a 3400 Fiero running off Phonedawgz harness. I would not hesitate to buy from him again. http://reddevilriver.com/ this is his site. Or contact him through Pennocks. For the little effort it takes I would go with the OBD II system with the stock ecu. I have ran my 3400 off OBD 1, 1.5 and 2, and it was well worth the upgrade to the latter. Pm me if you have any more questions, I have been working on my swap for many years and it has gone through many versions, and changes. If I were to do another I could probably have it running in a weekend, provided I had all the parts pre-purchased.