3.1l to 305

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Oct 27, 2007 | 04:14 PM
  #1  
I'm swapping from my 3.1l 700R4 to a 305 TH350. Can I please get specific details on this swap? I need to know what lines will be different, if my shifter and such will mount up, and whether or not i can still use my stock gauge cluster.
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Oct 27, 2007 | 08:46 PM
  #2  
Did you read the V6 to V8 sticky?

In order to get specifics, you'll need to give more specifics about your 305.
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Oct 27, 2007 | 08:48 PM
  #3  
Re: 3.1l to 305
Yessir i read the sticky,

Mostly i am concerned with the transmission swap. I do have the transmission crossmember that came with it, Both the 305 and TH350 are out of what I believe was a 1982 Z28. Shouldn't be real difficult right?

I am pretty sure the motor i am swapping with is a LG4 with an Edelbrock 4bbl carb. I am also sure that the TH350 has some mounting brackets on the tail shaft for the torque arm?
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Oct 27, 2007 | 09:06 PM
  #4  
TH350's were never put in 3rd gens by the factory. There were some put in Monzas in the late 70's that had the torque arm mount.

The TH200C, the 3-speed auto that was used in 3rd gens for 2 years, and the TH350 (6" tailshaft version) use the same crossmember and driveshaft length. Odds are you have a TH200C (3-speed auto with lock-up torque converter), unless someone swapped in the TH350 sometime in the past.

You will have to do some adapting of the fuel lines for the carb set-up. The V6 lines go up the driver's side of the engine compartment. The V6 uses an in-tank electric fuel pump. You'll either have to remove the electric, or get a return-style regulator to bring the pressure down to carb-friendly 4-7 psi.

Wiring will be a challenge. You can use what's available in the V6 harness, but you'll have to adapt some things, change lengths with others.

Shouldn't be real difficult? Depends upon what you call difficult. Easier than solving world hunger, perhaps.
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Oct 27, 2007 | 09:21 PM
  #5  
Re: 3.1l to 305
Well which do you think is more reasonable five7?

I can either pull my v6 and 700R4 to replace the rear freeze plugs, or i can pull them both out and set in a running 305?

Whats your input?
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Oct 27, 2007 | 09:43 PM
  #6  
Re: 3.1l to 305
Pics of motor and mostly tranny
3.1l to 305-pic-0162.jpg3.1l to 305-pic-0164.jpg


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Oct 27, 2007 | 09:49 PM
  #7  
Re: 3.1l to 305
a turbo 200c
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Oct 28, 2007 | 11:46 PM
  #8  
Re: 3.1l to 305
Quote: Well which do you think is more reasonable five7?

I can either pull my v6 and 700R4 to replace the rear freeze plugs, or i can pull them both out and set in a running 305?

Whats your input?
That's funny because the whole reason i'm doing the 3.1-350 swap is because of a bad motor mount
Good luck to you draco,take some pics (so I can cheat when i'm reading to install my 350.)
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Oct 29, 2007 | 12:05 AM
  #9  
Okay, it's got the bolt-on bracket for the torque arm, so it probably is a TH350 that someone swapped in.

I'd say go for the V8.

Just understand, "There's no such thing as a bolt-in."
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Oct 29, 2007 | 12:34 AM
  #10  
Re: 3.1l to 305
alright five7, thats the advice i was looking for :-p
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Oct 29, 2007 | 01:19 AM
  #11  
Re: 3.1l to 305
yea draco good luck with swappin motors,man u must of been lucky to get a motor like that
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Oct 29, 2007 | 01:30 AM
  #12  
Re: 3.1l to 305
Ahahahah yeah i might be...

Have we met before? hahaha
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Oct 29, 2007 | 02:28 AM
  #13  
Re: 3.1l to 305
cant say we have
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Oct 29, 2007 | 03:06 PM
  #14  
Re: 3.1l to 305
Hey five7, what all is going to be different between the 700R4 and the TH350? What will i need to do for the shift linkage, shift indicator, and transmission lines?
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Oct 29, 2007 | 05:01 PM
  #15  
Re: 3.1l to 305
well one difference is goin to be overdrive,the th350 doesnt have it,i have the shifter plate from the old 82 z28 that just shows P,R,N,D,2,1 ill give ya,the shifter linkage should work fine,the tranny lines might work from the v6 as i used the lines from that th350 on my 700r but accidently kinked them in the install and had to run new lines
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Oct 29, 2007 | 09:16 PM
  #16  
Back to your original question about gages, everything should work except the tach - it's calibrated differently for V6 than for V8.

The TH350 mount is in a different location than the TH700. If you find an early TH200C crossmember (I'll have one available in a few weeks), it'll make life easier. Can't tell for sure from the picture if that is a 6" or 9" tailshaft housing (go out and measure it), but the 9" allows the TH700 driveshaft to work. 6" will need a longer driveshaft like the TH200C had (guess what. . .).
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Oct 29, 2007 | 09:25 PM
  #17  
Re: 3.1l to 305
austin i have the driveshaft and crossmember so ill go dig them out and get them ready to go for when u pick up the motor
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