1990 350 tbi, 1997 305 vortec

Discussion in 'Engine Performance + Maintenance' started by swervin, Aug 11, 2017.

  1. swervin

    swervin Newbie

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    I just got a good deal on a 1988 eclb light duty 2500 4x4 maunual trans with a 350 tbi, i also have a 1990 thats identical other then its rclb which im restoring a bit right now, then my dad says he found a cheap auto 2 wheel 1997 with a vortec 305. I was wondering if i could switch heads and intake from a 350 tbi to the 305 vortec so i could make my tbi 350 a vortec 350 with 305 heads and intake and vise versa? Is it worth the time? And will i end up with 3 driveable trucks afterwards if its all done right? Or will i only have maybe 2 that are still moderatly easy to put back together and still run smooth? Also on a tight budget right now which makes things alot harder...
     
  2. skylark

    skylark I'm Awesome

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    The 305 vortec heads aren't the same as the 350 vortec heads. They will physically bolt up but the chambers are smaller meaning a higher than desirable compression ratio and the heads don't flow as well as the 350 versions. You will also need a vortec carb style intake manifold with an adapter for the tbi. Tbi heads on a vortec engine and trying to get it to run would be a nightmare do to way too high of fuel pressure, incompatible wiring and computer control.
    If you are on a budget then this doesn't sound like this is for you.
     
  3. swervin

    swervin Newbie

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    If i were to port and polish the 305 vortec heads to make them flow better would that we worth it? And i would need the tbi adapter even with a vortec intake? And ive heard of guys making an adjustable fuel pressure regulator. Not trying to argue with you here, im just getting more into mechanics and trying to figure out as much as i can! Thanks for your feedback deffinatly not as excited for that 305 vortec anymore.
     
  4. 98 Nitro

    98 Nitro Newbie

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    The 97 305 has a little less torque and a little more hp than a 350 tbi. With a computer tune it will outrun a stock 350 tbi truck. I like the 95 up interior better too. If it were me I'd drive the 97 and the nicer of the two tbi trucks, which is what I'm doing actually I have a 94 4x4 for winter and a 98 2x4 for the rest of the year.
    Having said that yes you could take the 305 heads have them machined for 1.94 valves and bolt them on a 350 with a vortec intake and gain some hp but I agree with skylark probably not worth it on a budget.
     
  5. swervin

    swervin Newbie

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    So for a 4x4 i might as well stick with the tbi how it is and maybe chip it later down the road? All 3 of my trucks are basically rust bucket beaters but im slowly trying to restore my 1990 as i had it first and started the resto befor even seeing the other 2 trucks probably going to daily the 2 wheel til its dead, sell it to a scrapyard, then switch insurance to the eclb and see where im at from there.
     
  6. 98 Nitro

    98 Nitro Newbie

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    The only thing mods I did to my TBI truck were an aftermarket exhaust and Hypertech power charger. I may add a tb spacer and pod spacer in the future but that is it with the finicky computers and low pressure fuel pump. A good writeup of these mods is on gmc4x4.com
     

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