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305 or 350

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Old Aug 25, 2010 | 03:11 AM
  #1  
lillee64's Avatar
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From: Baton Rouge, LA
Car: 1990 Iroc Z
Transmission: t56
Axle/Gears: 4:10
305 or 350

ok i have two engines, 1 is an 84 305 and the other is a 85 350. one of these will be going into my 90 iroc z. its a manual 700r. i want to upgrade to ported vortec heads, stroked, new cam, stuff like that eventually but i think newer 305 produce more hp than the older 350, plus both of these are truck engines so dont they have lower compression? what to do?
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Old Aug 25, 2010 | 03:23 AM
  #2  
Doom86's Avatar
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From: SE, Ohio
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73
Re: 305 or 350

What heads are on both motors?
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Old Aug 25, 2010 | 03:25 AM
  #3  
lillee64's Avatar
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From: Baton Rouge, LA
Car: 1990 Iroc Z
Transmission: t56
Axle/Gears: 4:10
Re: 305 or 350

both are stock
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Old Aug 25, 2010 | 03:31 AM
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Doom86's Avatar
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From: SE, Ohio
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73
Re: 305 or 350

Casting numbers tell you what heads they are. Most heads are stock and not all stock heads are the same.

If you don't intend to build the motor before putting it into the car then I would put the 305 in the car and put the 350 on the engine stand and start tearing it down for the vortec build.
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Old Aug 25, 2010 | 03:34 AM
  #5  
lillee64's Avatar
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From: Baton Rouge, LA
Car: 1990 Iroc Z
Transmission: t56
Axle/Gears: 4:10
Re: 305 or 350

i was thinking about putting in the 350 and selling the 305, i was gonna buy all my rebuild stuff part by part and just put it all together down the road
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Old Aug 25, 2010 | 08:44 AM
  #6  
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From: Pepperell, MA
Car: 1987 Trans Am
Engine: LQ9/L92
Transmission: 4L60E
Re: 305 or 350

its not gonna be easy to sell a 305; I gave mine away just to have some more room in my workspace. its much easier to take your time building up a motor if its not installed in your daily driver. what do you have for an engine now? is there anything wrong with it?
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Old Aug 25, 2010 | 12:20 PM
  #7  
lillee64's Avatar
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From: Baton Rouge, LA
Car: 1990 Iroc Z
Transmission: t56
Axle/Gears: 4:10
Re: 305 or 350

id have no problem selling my 305 for about $300 in my area, i kno the 350 is the better engine in the long run but is a 85 350 worth it? or should i get a newer one to build?
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Old Aug 25, 2010 | 01:36 PM
  #8  
Doom86's Avatar
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Joined: Oct 2004
Posts: 965
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From: SE, Ohio
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73
Re: 305 or 350

I'm with 1ADAN on this one good luck selling that 305.

If you can sell them easily do so and get a 87+ 350. If you plan to invest a good amount of money into the thing you may as well get a good base. There are a lot of good reasons to go roller. I have a torn down 4 bolt main 350 flat tappet block sitting in the back of my truck waiting for a trip to the scrapper just for that reason.
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Old Aug 25, 2010 | 01:48 PM
  #9  
lillee64's Avatar
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From: Baton Rouge, LA
Car: 1990 Iroc Z
Transmission: t56
Axle/Gears: 4:10
Re: 305 or 350

well most likely since i will be buying basically every part inside i might just buy another block too
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Old Aug 26, 2010 | 10:35 PM
  #10  
CanuckBird's Avatar
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From: Ontario
Car: 83 Z28
Engine: 355
Transmission: T5
Axle/Gears: 3:73
Re: 305 or 350

350 all day long....
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Old Aug 26, 2010 | 10:39 PM
  #11  
lillee64's Avatar
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From: Baton Rouge, LA
Car: 1990 Iroc Z
Transmission: t56
Axle/Gears: 4:10
Re: 305 or 350

ok i just got a 92 350 today, all taken apart though. what would be the best way to put it back together? and i want decent tq
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Old Aug 26, 2010 | 11:13 PM
  #12  
Doom86's Avatar
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Joined: Oct 2004
Posts: 965
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From: SE, Ohio
Car: '86 Z28, '91 RS
Engine: 305ci, 305ci
Transmission: TH200c (no kidding), TH700r4
Axle/Gears: 2.73, 2.73
Re: 305 or 350

What heads did it come with?
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Old Aug 26, 2010 | 11:17 PM
  #13  
lillee64's Avatar
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From: Baton Rouge, LA
Car: 1990 Iroc Z
Transmission: t56
Axle/Gears: 4:10
Re: 305 or 350

id have to look them up, i want to go vortec though
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Old Aug 26, 2010 | 11:27 PM
  #14  
lillee64's Avatar
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Posts: 268
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From: Baton Rouge, LA
Car: 1990 Iroc Z
Transmission: t56
Axle/Gears: 4:10
Re: 305 or 350

ok the block casting on my 350 is 10054727 and the heads are 14102185
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