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swapping 305 HO to 355 vortec

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Old Apr 16, 2012 | 08:00 PM
  #1  
midge54's Avatar
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From: Pennsylvania
Car: 86 Trans am
Engine: LG4
Transmission: T-5
Axle/Gears: 3.27 9 bolt posi
swapping 305 HO to 355 vortec

So i have my 84 Trans am 15th anniversary, 305 was absolutely trashed by p.o. I decided since the tranny has already been replaced might as well put a bigger engine in it versus trying to fix the tired 305. I have a 2 bolt 010 350 block .30 over. I have a summit stage 1 dual plane intake and vortec 061 heads. My uncle scrapped my block heads and intake before i could strip anything off of them. So i am missing all my sensors, my ported vaccum switch, coolant fittings etc. So what all am i going to have to buy to drop this 350 in my car. Im staying with the factory q-jet carb setup
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Old Apr 16, 2012 | 08:48 PM
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: swapping 305 HO to 355 vortec

Originally Posted by midge54
I have a summit stage 1 dual plane intake and vortec 061 heads. Im staying with the factory q-jet carb setup
Is that a Vortec intake ?
only a Vortec intake will fit Vortec heads
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Old Apr 16, 2012 | 08:51 PM
  #3  
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From: Pennsylvania
Car: 86 Trans am
Engine: LG4
Transmission: T-5
Axle/Gears: 3.27 9 bolt posi
Re: swapping 305 HO to 355 vortec

Originally Posted by vetteoz
Is that a Vortec intake ?
only a Vortec intake will fit Vortec heads
yep vortec specific intake, engine is already assembled and ready to drop in, planning to do it this weekend, just trying to get my ducks in a row since all my sensors and plug ins are missing off the block heads and intake
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Old Apr 16, 2012 | 08:57 PM
  #4  
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: swapping 305 HO to 355 vortec

For a carb engine to run all you basically need are the gauge sensors.
oil pressure and temp
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Old Apr 16, 2012 | 08:59 PM
  #5  
midge54's Avatar
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From: Pennsylvania
Car: 86 Trans am
Engine: LG4
Transmission: T-5
Axle/Gears: 3.27 9 bolt posi
Re: swapping 305 HO to 355 vortec

what about knock sensor
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Old Apr 17, 2012 | 11:10 PM
  #6  
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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
If you are sticking with the factory carb, you'll need the CTS on the thermostat housing, and knock sensor in the block coolant drain. The O2 sensor is in the driver side exhaust manifold. The rest of the sensors aren't on the engine (MAP and BARO).

The temp gauge sender was in the driver side head. Can we assume you had a mechanical radiator fan? If so, you don't need the fan switch that went in the passenger side head for an electric radiator fan. The oil pressure gauge sender goes in the port close to the distributor.

The original engine had other stuff (EGR, A.I.R.), but you don't need them to run.

You have the original carb and distributor, right?
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Old Apr 18, 2012 | 08:28 AM
  #7  
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From: Pennsylvania
Car: 86 Trans am
Engine: LG4
Transmission: T-5
Axle/Gears: 3.27 9 bolt posi
Re: swapping 305 HO to 355 vortec

Yea I have the original carb and distributor. My original 305 didn't have the cts in the stat housing. Actually my car came with factory electric fan so I'll need that switch. I though a knock sensor wasn't required for carbed engine. Also the air and egr are long gone since my pump was locked up and my new intake doesn't have the egr setup
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Old Apr 18, 2012 | 02:26 PM
  #8  
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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
Okay, in '84 only the HO had the knock sensor. Did you convert to electric fan, or did it come from the factory that way? I thought only the HO had electric fan in '84 (and not completely sure about that).
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Old Apr 18, 2012 | 04:34 PM
  #9  
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From: Pennsylvania
Car: 86 Trans am
Engine: LG4
Transmission: T-5
Axle/Gears: 3.27 9 bolt posi
Re: swapping 305 HO to 355 vortec

Yes this was an 84 ho cause it's going in a 15th anniversary trans am so does that mean I'll need the knock sensor, it's factory electric fan
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