TBI 350 to C 383 Swap

calli.uwu

n00b
Aug 4, 2021
4
1
I previously had the 350 from my ‘80 K20 converted to a 383. I have a 1993 G20 conversion van with the TBI 350. I was thinking of doing basically the same, convert it to a 383 but convert this one to a carb and then drop it in my Cutlass. Is it possible to do both, and is it relatively cheap and easy? I don't want to apply too much of my time and wallet to this endeavor. Just asking because I’ve never heard it done like this.
 
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ck80

Comic Book Super Hero
Feb 18, 2014
4,663
113
Because you said relatively, it depends on your definition of cheap and easy.

Where you live, and what you own or can buy used, change the relative costs of making a centerbolt tbi engine into a mechanical pump carb motor.

To be honest, you need to do some research and really read up on things, lots of build threads here. Play with the search function.

Once you get a working knowledge it's easier to fill in your remaining gaps.
 
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May 18, 2022
2
3
I'm no master mechanic, but I don't think you can just bore out a 350 to a 383 just like that. Like the first comment said, you need a 383 crankshaft, rod, and 10.5-1 piston set. As for the carb conversion, it should be pretty easy and cheap. You'll need an intake and carb for a 350 and they sell plenty of conversion kits
 
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78Delta88

Master Mechanic
Supporting Member
May 23, 2022
417
43
SW Arizona
I previously had the 350 from my ‘80 K20 converted to a 383. I have a 1993 G20 conversion van with the TBI 350. I was thinking of doing basically the same, convert it to a 383 but convert this one to a carb and then drop it in my Cutlass. Is it possible to do both, and is it relatively cheap and easy? I don't want to apply too much of my time and wallet to this endeavor. Just asking because I’ve never heard it done like this.
Do you have pics of your 80 K20? I had a 80 GMC 3/4 ton 4x4 Nordic Blue, wish I never sold.

The TBI 350 is not a bad engine but the heads are not very "good". You would be better starting with a Vortec 5.7. The good thing about the truck 350 TBI is that it has 4 bolt mains.
 

Yav8

Master Mechanic
Aug 19, 2014
268
43
Manitowoc wis.
The best of building a 383 is the TQ and HP gains. As for the block the best one to start with is the late model vortec 880 casting. There a a lot of them out their and the all came set up for a hyd. roller cam. No more flat lobes and a total motor tare down to fix the bad cam. Also they all came with the good vortec heads 062 or the 906 castings. Comp. cams makes a set of behive spring and small retainers the fit the vortec heads and install at 1.70 just like stock and will handle up to .525 lift. I have done quit a few of these head upgrades and they spin to 6000 rpm. no problem even with the pressed in studs.
 
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CopperNick

Royal Smart Person
Supporting Member
Feb 20, 2018
2,407
113
Canada
Assuming here that the "880" is the last three digits of the block casting number for that Vortec enigne. Can you post the entire number and the years and model in which it appeared?


Nick
 

Built6spdMCSS

Comic Book Super Hero
Jun 15, 2012
2,770
113
Florida Beach
I'm no master mechanic, but I don't think you can just bore out a 350 to a 383 just like that. Like the first comment said, you need a 383 crankshaft, rod, and 10.5-1 piston set.
You don't need that specific "10.5:1 Piston Set"...can throw whatever slugs you wanted in it for what you are building
 
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Built6spdMCSS

Comic Book Super Hero
Jun 15, 2012
2,770
113
Florida Beach
I hardly answer threads like this because people seem to leave out how much they want to spend.

"I want to build this..."

We need a budget here.....
 
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Yav8

Master Mechanic
Aug 19, 2014
268
43
Manitowoc wis.
Assuming here that the "880" is the last three digits of the block casting number for that Vortec enigne. Can you post the entire number and the years and model in which it appeared?


Nick
They only came in trucks vans and the big SUVs from the years 1996-2000. I do not have the full number but the casting number will be on the side of the block and on the back pad along with 5.7 meaning it a 350 cubic inch.
 
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ELCAM

G-Body Guru
Jun 19, 2021
808
93
10243880 = 350 CID, 1995-2000, Vortec truck, crate motor and ZZ4, 2 or 4 Bolt main, roller cam, one piece rear main seal.
 
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