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possible 305 to 350 problems?

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Old Jul 25, 2011 | 10:56 AM
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musclecarguy91's Avatar
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From: Pennsylvania
Car: 91 Camaro Z28
Engine: 350
Transmission: auto
possible 305 to 350 problems?

I have a 91 Z28 with the 700r4 trans. I'm doing the typical 305 to 350 swap. I just got the 350 back completely rebuilt. I'm not sure if these questions fit in this section so I apologize if they don't. I have a 80's truck 350 and the camaro has the vortec engine. Will the cerpantine set up bolt up to the motor? or will I need different brackets or just forgo the whole cerpantine set up? Another question I have is: how much controller does the computer have over the automatic transmission? And my last is: Is the fuel pump in the gas tank? The mechanic we go to said that it is?
Any help would be great. Thanks
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Old Jul 25, 2011 | 11:34 AM
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Re: possible 305 to 350 problems?

Originally Posted by musclecarguy91
I have a 91 Z28 with the 700r4 trans. I'm doing the typical 305 to 350 swap. I just got the 350 back completely rebuilt. I'm not sure if these questions fit in this section so I apologize if they don't. I have a 80's truck 350 and the camaro has the vortec engine. Will the cerpantine set up bolt up to the motor? or will I need different brackets or just forgo the whole cerpantine set up? Another question I have is: how much controller does the computer have over the automatic transmission? And my last is: Is the fuel pump in the gas tank? The mechanic we go to said that it is?
Any help would be great. Thanks
The whole serpentine setup will bolt right up to the 350.
The computer controls the torque converter lockup, a 4-wire connector on the driver's side.
If you're wanting to remove the computer, there are lockup kits available.
The fuel pump is in the tank. If you had the TPI, then you gotta change the pump to a much-lower-pressure TBI-style fuel pump, then add a bypass-style pressure regulator. If you had the TBI, then ayou just need the bypass style pressure regulator to use a carburetor.
The question many of us will have for you: Why go carbureted instead of keeping the EFI?
Also, having a 700R-4 behind your 305 means that you had the worst of the V8 exhaust systems. The small 1.875" exhaust manifolds, and a single 2.25" exhaust. Your 350 will want something better. Preferably headers and a 3" exhaust.
And you probably had the 2.73:1 axle. Think about changing that, too.
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Old Jul 25, 2011 | 12:45 PM
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musclecarguy91's Avatar
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From: Pennsylvania
Car: 91 Camaro Z28
Engine: 350
Transmission: auto
Re: possible 305 to 350 problems?

Originally Posted by ronnjonn
The whole serpentine setup will bolt right up to the 350.
The computer controls the torque converter lockup, a 4-wire connector on the driver's side.
If you're wanting to remove the computer, there are lockup kits available.
The fuel pump is in the tank. If you had the TPI, then you gotta change the pump to a much-lower-pressure TBI-style fuel pump, then add a bypass-style pressure regulator. If you had the TBI, then ayou just need the bypass style pressure regulator to use a carburetor.
The question many of us will have for you: Why go carbureted instead of keeping the EFI?
Also, having a 700R-4 behind your 305 means that you had the worst of the V8 exhaust systems. The small 1.875" exhaust manifolds, and a single 2.25" exhaust. Your 350 will want something better. Preferably headers and a 3" exhaust.
And you probably had the 2.73:1 axle. Think about changing that, too.
Yeah it is TPI and I have the carb bought already, but it was under my understanding that the whole TPI set up won't fit the 350 with the 350 heads?
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Old Jul 25, 2011 | 12:49 PM
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musclecarguy91's Avatar
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From: Pennsylvania
Car: 91 Camaro Z28
Engine: 350
Transmission: auto
Re: possible 305 to 350 problems?

I assume you can get all that stuff from summit?
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Old Jul 25, 2011 | 01:26 PM
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Re: possible 305 to 350 problems?

I'd keep the TPI. What cam is in the 350? That may need to be changed.
If the heads on the 350 are pre '87, then you need to change the lower intake manifold, "base" to an '85-'86 305 or '85-'91 'vette version.
All the rest of the TPI stuff will work with just a custom chip, unless you're making more HP than the 305 injectors can support at a 100% duty cycle with extra pressure.
If you must go carbureted, then the pump and regulator can both be ordered from Summit.
Short term, the cost is about the same either way, if you add in the cost of the new carb. I'd return it for a full refund.
Long term, the TPI will pay for itself just in MPG. Plus the improved driveability is wonderful.
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Old Jul 25, 2011 | 01:53 PM
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musclecarguy91's Avatar
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From: Pennsylvania
Car: 91 Camaro Z28
Engine: 350
Transmission: auto
Re: possible 305 to 350 problems?

not quite sure of the exact came specs of the came. I believe it has like 495 or 5 something lift. And the heads are from like a 86 to 94 truck or 84 to 96. I know if was carbed when I took it apart.
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Old Jul 25, 2011 | 01:56 PM
  #7  
musclecarguy91's Avatar
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From: Pennsylvania
Car: 91 Camaro Z28
Engine: 350
Transmission: auto
Re: possible 305 to 350 problems?

So as long as I put that regulator on I won't need to drop the gas tank?
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Old Jul 25, 2011 | 07:57 PM
  #8  
camaronewbie's Avatar
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From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: possible 305 to 350 problems?

www.thirdgen.com/carbswap answers some of this
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Old Aug 26, 2011 | 07:06 AM
  #9  
allgood's Avatar
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From: Kansas City, KS
Car: 92 WS6 Trans am convertible
Engine: ls 6.2
Transmission: 4l80
Axle/Gears: 2.73's
Re: possible 305 to 350 problems?

i did a 305tpi to 350tpi swap what all do i need to change to complete the swap
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