Carbed 3.4L swap (Page 1/1)
BubbaCV2008 DEC 16, 12:07 PM
I've had my Fiero (1986) for 3 years now and the old 2.8L in it has started to have a lifter tick and I'm looking for all the info I need to do a 3.4L swap (not 3400 motor)

I have the 4 speed muncie manual parred with a 2.8L v6

I would like to make the 3.4L carbureted and have a distributor, I'm looking for a simple swap to do and one that wont take a bunch of wiring

I know a few things about that swap but I'm looking to get more info on it like year of engine needed, clutch needed and flywheel needed, fuel pump needed and its my daily currently so Im looking at around 1 to 2 weeks that it could be down for while I do the swap

and I'll try to answer back quick if anyone has any more questions needed about my car

[This message has been edited by BubbaCV2008 (edited 12-16-2025).]

1985 Fiero GT DEC 16, 02:12 PM

quote
Originally posted by BubbaCV2008:

I've had my Fiero (1986) for 3 years now and the old 2.8L in it has started to have a lifter tick and I'm looking for all the info I need to do a 3.4L swap (not 3400 motor)

I have the 4 speed muncie manual parred with a 2.8L v6

I would like to make the 3.4L carbureted and have a distributor, I'm looking for a simple swap to do and one that wont take a bunch of wiring

I know a few things about that swap but I'm looking to get more info on it like year of engine needed, clutch needed and flywheel needed, fuel pump needed and its my daily currently so Im looking at around 1 to 2 weeks that it could be down for while I do the swap

and I'll try to answer back quick if anyone has any more questions needed about my car




For the 3.4 swap, you would need the engine from a 1993-1995 firebird/Camaro, flywheel is the 88 Fiero flywheel (87/earlier is externally balanced, the 3.4 and the 88 Fiero 2.8 were internally balanced, and used the same flywheel) clutch is whatever can stand the power you intend to make, that is made to work with the transmission and stock engine. I don't know the fuel pump requirements for a carb, but I do know a good quality stock Fiero fuel pump (Rodney Dickman's stock v6 replacement) provides plenty of flow and pressure for a more powerful engine (I'm using it with a 3400/iron head/turbo, with no issues)

I don't know carbs and I don't know what your goals are, but the 3400 engine will generally have a similar amount of work to install compared to a Camaro 3.4, but they are much more plentiful, cheap and are stronger with a better bottom end. The Iron heads, intakes, carbs, distributor, etc. from the 2.8 or anything designed for it or the Camaro 3.4 will bolt right on to the 3400 block and bottom end. The 3400 does have dished pistons, so the compression will be lower with the iron heads used on the 3.4 or 2.8, but the 3.4 pistons (and the 3.4 dual overhead cam pistons for even higher compression) will swap out with no issues and give you stock or higher compression.
82-T/A [At Work] DEC 16, 03:10 PM

quote
Originally posted by BubbaCV2008:

I've had my Fiero (1986) for 3 years now and the old 2.8L in it has started to have a lifter tick and I'm looking for all the info I need to do a 3.4L swap (not 3400 motor)

I have the 4 speed muncie manual parred with a 2.8L v6

I would like to make the 3.4L carbureted and have a distributor, I'm looking for a simple swap to do and one that wont take a bunch of wiring

I know a few things about that swap but I'm looking to get more info on it like year of engine needed, clutch needed and flywheel needed, fuel pump needed and its my daily currently so Im looking at around 1 to 2 weeks that it could be down for while I do the swap

and I'll try to answer back quick if anyone has any more questions needed about my car





Hi Bubba, just wanted to ask why you want to make it carbureted... is that because you think the swap will be easier? If you go with the 3.4 Camaro / Firebird block like 85 Fiero GT stated, all the existing wiring will continue to work on your car as-is. Literally, the only thing you do is swap out the motor, drill for starter bolt holes, and get larger injectors (17#). The existing computer system will work on your Fiero... for what it's worth.

All that aside, I'll answer your question. The 3.4 Camaro / Firebird block has a camshaft that is identical to the one in the Fiero. There is currently a freeze plug installed in place of where the distributor goes, so you have to knock that out, and you can then install an older distributor. If you're going with carburetor, you'd want something from like a Chevy Citation / X11 from the late 70s or early 80s. You can go on Rock Auto, and look up Chevy Citation... around 1981, and look up parts for a distributor. You'll find something like a vacuum advance distributor, and that's the one you can use (for a 2.8).

For the Intake manifold, Edelbrock sells an intake specifically for the 2.8-3.4 V6/60 that you'll want to buy. It's a two-piece manifold called the Performer and then a top piece called the Torker-2. These are the only ones redily available, otherwise, you'll have to go with an old 2.8 intake manifold from, again... a Chevy Citation, which will be very sub-par.

The problem with the Edelbrock manifold is that it's designed for a longitudinal installation, so the carburetor mounts on a pitched angle, which when installed in the Fiero, has it angled towards the driver's side. So you'll want to take it to a machine shop and have it planed and the holes re-tapped (will probably cost about ~$50).

As for fuel pump... you probably want to keep the factory in-tank pump since it works best... I would replace your V6 pump with one specifically for your year Fiero, but meant for a 4 cyl. The 4 cyl Fiero pumps produce anywhere from 12-14 PSI. A carburetor on the other hand typically uses only 4-8 PSI. The Fiero's fuel injection system, as well as the pickup and everything, is a return-style system. So you'll want to get a device that allows you to regulate fuel pressure and returns the unneeded fuel back into the return line. You'll want too make custom fuel lines for this, so get a flaring tool.

As for the gauges... the nice thing is that the gauge cluster is independent of the ECM... so your oil pressure, temperature gauge, tachometer, etc... all will connect up to the engine in the way they always have. You can literally just keep the old sensors and screw them into the new block.

Everything else... exhaust, etc... will just nolt up and use it as-is.

For a carburetor, you'll probably want to go with a smaller Edelbrock carburetor. You can use a 4-barrel on the 3.4 since it's big enough... get something like an Edelbrock Performer, like a 1403 or something less than 500cfm.

Honestly... all this stuff is not cheap... with the money you're looking to spend, you should at least TRY to use the existing wiring and everything since your car is already running. Worst case, the amount of money you'd be spending on the carburetor stuff... you could just get an aftermarket system like a FAST EZ-EFI 2.0 system.


For the absolute cheapest way to go about this... find yourself a Chevy Citation with a carbureted 2.8 that someone pulled, and swap over the intake, distributor, and carburetor. It'll be seriously underpowered though, but at least then you can upgrade from there as your wallet allows.
82-T/A [At Work] DEC 16, 03:21 PM
I'll also just add... if you're really looking for a way to do this and money is not necessarily an issue... there are a bunch of old intake manifolds out there that are very high-performance oriented. Back in the day, everyone from Edelbrock and Holley made several options for this engine... but Offenhauser also had a couple of intakes as well. Right now, the only company that sells new intakes are Edelbrock, and I'm sure it's because they're left over new old stock. But Offenhauser had one that allowed you to connect 6 individual Solex or Carter carburetors. It came with the linkage and everything. I'd thought about doing this when I was a lot younger, but clearly lacked the funds back then.

Good luck finding any of those... they are basically unobtainium... and those that weren't snagged by parts suppliers, were probably recycled because no one knew what to do with them. But the V6/60, when built well, can really be wound out when head work has been done. These engines were used for circle track racing, and there was even a company that bought up all the aluminum GM Performance Parts versions of them. Those ended up in some version of an airplane (which is really weird). But at 60 degrees, the sound this engine produces when opened up is similar to what some of the earlier Ferraris sounded like... (like the Dino, etc.). You need a tuned exhaust of course, but the engine sounds really good... and not just like a Cummings diesel in a yacht.
hnthomps DEC 16, 03:27 PM
Years ago, I swapped my worn out 2.8 V6 for a Camero/Firebird 3.4 V6. At that time I even added a turbo to the 3.4 engine. Aside from the starter relocation and changing from stock to larger injectors, everything worked for the new engine. The turbo did require a few additional wires but not the engine itself. The car is now my backup show car and still runs quite nicely.

For a similar price, you may want to consider a 3800 NA or SC engine. I have two 3000 SC engines (Stage II and III) and there is a noticable increase in performance with the 3800 SC engines.

Nelson
Dennis LaGrua DEC 16, 05:49 PM
I would not recommend using a carburetor. By the 1980's carburated auto engines were considered obsolete. They are not emissions legal nor will they provide good gas mileage and engine longevity. If you are intending to do a 3.4L P/R swap, the 2.8L harness and ECM is just a plug in job. Its an easy swap for a bit more power.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Mickey_Moose DEC 17, 01:26 PM
Far easier just to keep the fuel injection system that is now on the car. More work to swap to a carb.

As others have said, just take the top end (intake/etc) off your 2.8l and install on the 3.4l, relocated the starter and bolt back in (I think you might have to swap the water pump if using the Camaro engine) and cut a new timing mark on the harmonic balancer if using the 3.4l one (you can reuse your 2.8l one if in good shape). The 3.4l swap is the easiest with min work swap out there (unless you are installing it in a 84).

I think my swap took something like 2 days (I used the GM 3.4l HT crate engine). I done swaps before, so your time may vary.

Rodney Dickman may still sell the start relocation jig (and other parts you may need). https://rodneydickman.com/i...fb4634917c614489d02b

[This message has been edited by Mickey_Moose (edited 12-17-2025).]

BillS DEC 19, 04:45 PM
Agree that the use of a carb is a significant negative step and I'm not sure why you want to do it that way? The swap you contemplate is a pretty straight forward one. I did the same sort of thing, putting a 3.4 into a 1958 MG with a rebody on it and I had no issues with keeping the injection.

I even had a friend do a computer engraved 'MG' on the upper plenum. Did some light mods/tuning for c. 190 bhp and it moves a couple of thousand pounds along quite well.
olejoedad DEC 19, 06:27 PM

quote
Originally posted by BillS:

Agree that the use of a carb is a significant negative step and I'm not sure why you want to do it that way? The swap you contemplate is a pretty straight forward one. I did the same sort of thing, putting a 3.4 into a 1958 MG with a rebody on it and I had no issues with keeping the injection.

I even had a friend do a computer engraved 'MG' on the upper plenum. Did some light mods/tuning for c. 190 bhp and it moves a couple of thousand pounds along quite well.







Oh, that's sweet!
BillS DEC 19, 06:45 PM

quote
Originally posted by olejoedad:


Oh, that's sweet!



Yes, 190 bhp and 2100 lbs. is a good combination. And the 15x6 Dayton wires with 215x60 look right and give a lot of additional grip. Runs a T5 5 speed manual trans. Much peppier than a Fiero with 140 bhp that weighs around 600 lb. more. But my 88 Fiero GT turbo with 300 bhp was also a hoot.