2.8 swap to 3.1
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Junior Member
Joined: Sep 2007
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From: Texas
Car: 84 Firebird / 91 Camaro
Engine: 2.8 / 3.1
2.8 swap to 3.1
I have a 1991 RS Camaro 3.1 Fuel injection Engine, i would like to put in place of the 2.8 Carb engine in a 1984 LE Firebird. My questions is the intake and carb from the 2.8 able to mount up on the 3.1? And is the wiring harness and the comp needed to be swapped?
Joined: Mar 2000
Posts: 43,187
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Thread Starter
Junior Member
Joined: Sep 2007
Posts: 19
Likes: 0
From: Texas
Car: 84 Firebird / 91 Camaro
Engine: 2.8 / 3.1
Re: 2.8 swap to 3.1
I understand that the blocks will bolt up not prob my question is changing the 3.1 fuel injection to carb, from the 2.8?
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From: Northeast CT
Car: '89 IROC-Z
Engine: LSx
Transmission: T-56
Axle/Gears: 3.42
Re: 2.8 swap to 3.1
If you have the entire 3.1 harness and ECM you should just use the MPFI, more power and better fuel economy. As far as the carb intake boling up I dont see any issue.
Thread Starter
Junior Member
Joined: Sep 2007
Posts: 19
Likes: 0
From: Texas
Car: 84 Firebird / 91 Camaro
Engine: 2.8 / 3.1
Re: 2.8 swap to 3.1
Thank you for the reply, i do have the harness and ecu but to me a temp swaps so i dont want to mess with the wiring or fuel system too much.
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Joined: Oct 2008
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From: Kutztown, PA
Car: Formula/RS
Engine: 5.7L/60 degree
Transmission: both 700r4
Axle/Gears: 2.73 lsd and 3.23, respectively
Re: 2.8 swap to 3.1
I just did 2 of these swaps... went from the 3.1L that was fubar, to a 2.8L... now going back to the 3.1L currently
ECU and wiring harness get swapped in with the 3.1L engine... also depending on the year check the accesories and the water pump especially since they swapped the rotation in 87 and went to serpentine...
motor is so small I didn't even pull the radiator... plenty of room to pull the (count them) 6 bolts holding the tranny to the motor... the motor mounts and the exhaust manifolds... and of course the harness and rad hoses/fan power connector
There is a junction behind the right headlamp... if there's allot of corrosion, you could break some of these wires... be careful...
otherwise there is one screw holding the main plug where it goes into the firewall. don't forget the 02 sensor and rip the wire out by accident (doh!)
one last thing... as a nickels worth of free advice from someone that has done this... take the top of the intake plenum off... Why? because the MAP vacuum nipple breaks off EASY when it comes it contact with the chain off your hoist... as do all of the vacuum components... (which you will also need the map sensor for the 3.1L btw) also make sure that if you have tranny cooling lines they are slipped free of the oil pan clip that holds them in place...
don't think I'm forgetting anything... have fun, and be sure to tighten the grounds properly... I didn't do this and was running rich for a week after the swap and kept fouling plugs
ECU and wiring harness get swapped in with the 3.1L engine... also depending on the year check the accesories and the water pump especially since they swapped the rotation in 87 and went to serpentine...
motor is so small I didn't even pull the radiator... plenty of room to pull the (count them) 6 bolts holding the tranny to the motor... the motor mounts and the exhaust manifolds... and of course the harness and rad hoses/fan power connector
There is a junction behind the right headlamp... if there's allot of corrosion, you could break some of these wires... be careful...
otherwise there is one screw holding the main plug where it goes into the firewall. don't forget the 02 sensor and rip the wire out by accident (doh!)
one last thing... as a nickels worth of free advice from someone that has done this... take the top of the intake plenum off... Why? because the MAP vacuum nipple breaks off EASY when it comes it contact with the chain off your hoist... as do all of the vacuum components... (which you will also need the map sensor for the 3.1L btw) also make sure that if you have tranny cooling lines they are slipped free of the oil pan clip that holds them in place...
don't think I'm forgetting anything... have fun, and be sure to tighten the grounds properly... I didn't do this and was running rich for a week after the swap and kept fouling plugs
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