L03 to LB9
08-31-2010, 12:27 AM
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Car: 1991 Firebird
Engine: 305 TBI
Axle/Gears: 2.73s
L03 to LB9
So I have a 91 firebird and as of today an 87 trans am. The trans am was in a front end accident but runs perfectly fine 104k miles on it. I want to take the lb9 out of my trans am and put it in the firebird. Obviously I have all the parts because the trans am still runs so ive got the ECM and harness and everything.
Was just wondering if there would be any extra work required going from 1991 tbi motor to 1987 tpi motor?
Was just wondering if there would be any extra work required going from 1991 tbi motor to 1987 tpi motor?
08-31-2010, 02:08 AM
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Car: seeking '90.5-'92 'bird hardtop
Engine: several
Transmission: none
Axle/Gears: none
Re: L03 to LB9
The big issue is you need to take the TBI tank out and put a new TPI fuel pump in it. You might get by with having the TBI pump feeding a "frame-rail" mounted booster pump, but TBI runs at 12-14 psi, while TPI requires more like 39 psi. Don't trust used pumps. They tend to fail, and they're aggravating to replace. Never skimp when you have to drop your tank.
08-31-2010, 12:38 PM
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Car: 1991 Firebird
Engine: 305 TBI
Axle/Gears: 2.73s
Re: L03 to LB9
Ok thanks probably a good warning cause i was definately just going to use the used fuel pump. What about the belt assembly the 87 does not use a serpentine. Would I just use the serpentine currently in the 91?
08-31-2010, 04:20 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
You can use the serpentine system on the TPI engine. In fact, it might be easier than swapping out the wiring for the accessories.
The '91 has VATS and a vehicle speed sensor (VSS) buffer, which the '87 won't have. You will need to by-pass the VATS (see the tech article linked from the TGO homepage), but I'm not completely clear on the details of the VSS wiring.
The '91 has VATS and a vehicle speed sensor (VSS) buffer, which the '87 won't have. You will need to by-pass the VATS (see the tech article linked from the TGO homepage), but I'm not completely clear on the details of the VSS wiring.
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