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Discussion Starter · #1 · (Edited)
I have a 1991 S10 Baja i’ve been working on and finally got it running for the first time in over 15 years. I was having the typical valve seal issues and it was something i didn’t want to tackle myself so i sent it off.

The shop working on the truck noticed a good bit of sludge builtup and recommended pulling and ultra-sonic cleaning the heads, which i was fine with.

Upon pulling the intake to the job, they found the below mess and a cracked lifter, some bent push rods, and some cam wear.
I am hoping the bottom end is okay as the truck seemed to run fine but who knows.

I want to build the 4.3 and after doing some of my own research digging around and knowing these engines for a bit, i’ve always heard that 96+ vortec heads are a great stock upgrade. I have a 1991 NON balance shaft engine and want to keep the stock TBI. Im told if i plan to keep the TBI with those heads i need a certain intake and possibly a redrill of some holes.

If anyone has a parts list or some help getting everything i’d need to make that happen along with cam and intake recommendations i’d love to hear them. I am planning to have the shop redo all the bearings, rings, gaskets, etc (light rebuild) but looking to upgrade “on a budget”. I have headers ordered but need info on the additional pieces that would make this thing a nice, peppy street truck. Thanks!

Automotive tire Motor vehicle Automotive wheel system Rim Engineering
 

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2003 Sonoma SLS ext. cab 4.3L / 4x4
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Time to pull it and hot tank it....that's a mess.
Holy moly - it looks like a herd of Grunge Gremlins went on a spree - I'm w/ @Rhotpursuit on his suggestion. And IMHO, if any other significant issues are discovered, it may be time to pause & consider (time, budget, cost, etc.) a replacement engine rather than a rebuild.
 

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Discussion Starter · #4 ·
Completely understood and engine is definitely getting pulled. Regardless if we re-use the bottom end or get a new engine, im looking for a parts list of good intake, heads, cam, etc from a performance perspective i can look at getting for the 4.3 while maintaining the stock TBI and sensors.
 

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I have a 1991 S10 Baja i’ve been working on and finally got it running for the first time in over 15 years. I was having the typical valve seal issues and it was something i didn’t want to tackle myself so i sent it off.

The shop working on the truck noticed a good bit of sludge builtup and recommended pulling and ultra-sonic cleaning the heads, which i was fine with.

Upon pulling the intake to the job, they found the below mess and a cracked lifter, some bent push rods, and some cam wear.
I am hoping the bottom end is okay as the truck seemed to run fine but who knows.

I want to build the 4.3 and after doing some of my own research digging around and knowing these engines for a bit, i’ve always heard that 96+ vortec heads are a great stock upgrade. I have a 1991 NON balance shaft engine and want to keep the stock TBI. Im told if i plan to keep the TBI with those heads i need a certain intake and possibly a redrill of some holes.

If anyone has a parts list or some help getting everything i’d need to make that happen along with cam and intake recommendations i’d love to hear them. I am planning to have the shop redo all the bearings, rings, gaskets, etc (light rebuild) but looking to upgrade “on a budget”. I have headers ordered but need info on the additional pieces that would make this thing a nice, peppy street truck. Thanks!

View attachment 355406
Also.....WOOOOOOWWWW 🤢 🤕 🤮(not the truck! The truck sounds awesome, thst sludge tho!)
 

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Is anyone familiar with performance parts for these engines? Thats specifically what i need help with dialing in at this point
For almost about the same money that you would dump into a remanufactured 4.3 long block you could put a 4.8 or 5.3 LS. It would cost more to build up the 4.3 than it would to do an LS swap and you would make more power with a Ls swap.
 

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Discussion Starter · #12 ·
For almost about the same money that you would dump into a remanufactured 4.3 long block you could put a 4.8 or 5.3 LS. It would cost more to build up the 4.3 than it would to do an LS swap and you would make more power with a Ls swap.
Has anyone here ever rebuilt and slightly upgraded a stock 4.3, and what parts did they use. Thats the only question i need answered.

I don’t want all the expense and fab time that comes with putting an entirely different and larger drivetrain in this truck as space is already an issue with the 4x4.

Can anyone step in here?
 

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Stock computer? Very little you can do in the way of cam upgrades, TBI and lumpy cams do not play together well. Something in the "RV cam" range, under 220 with a wide LSA.
Headers help but many say they don't help much at all.
Deck the block to leave the pistons .005 in the hole, use true flat tops with valve reliefs, not GM's shallow dish. Shoot for .035 - .040 quench.
TORQUE PLATE HONE - don't pass up on this, you'll have better compression and less blowby - more power, cleaner oil, win-win.
Vortec heads won't work with a throttle body unless you upgrade to the Edelbrock or GM intake made just for it. Have the shop clean up the casting flash and any ridges in the ports. Clean up, not changing the shape. Use back-cut valves for increased flow. Street valve job, not race, you need wider margins to help dissipate heat from the valve.
Leave the throttle body alone, it's big enough for a 350 to make decent power, you won't need any more. Just rebuild what you have.
 

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Discussion Starter · #14 ·
Stock computer? Very little you can do in the way of cam upgrades, TBI and lumpy cams do not play together well. Something in the "RV cam" range, under 220 with a wide LSA.
Headers help but many say they don't help much at all.
Deck the block to leave the pistons .005 in the hole, use true flat tops with valve reliefs, not GM's shallow dish. Shoot for .035 - .040 quench.
TORQUE PLATE HONE - don't pass up on this, you'll have better compression and less blowby - more power, cleaner oil, win-win.
Vortec heads won't work with a throttle body unless you upgrade to the Edelbrock or GM intake made just for it. Have the shop clean up the casting flash and any ridges in the ports. Clean up, not changing the shape. Use back-cut valves for increased flow. Street valve job, not race, you need wider margins to help dissipate heat from the valve.
Leave the throttle body alone, it's big enough for a 350 to make decent power, you won't need any more. Just rebuild what you have.
This is what i needed. Thank you. I did read some about the intakes and it appears you may need to have an ECM upgraded to handle those. I found a guy on facebook who does the upgrades on the ECM but unsure if there is someone better on here who can handle that.

If im gauging correctly from what you’re saying, its either upgrade the computer or don’t bother moving away from stock at all.
 

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Stock computer can handle a small RV cam but nothing with any lump in the idle.
Same things work on a 4.3 that work on an 5.7L. There are a ton more parts available for the V8 which can be aggravating if you're building a V6.
I build one in a '91 Astro van. Idled like shit but would burn tires like a V8. Cam I used was too big, it has roughly the specs of the old flat tappet L79.
I wouldn't go past teens in .050 duration and a wide LSA to keep overlap down and vacuum up in the intake.
 

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Discussion Starter · #16 ·
Stock computer can handle a small RV cam but nothing with any lump in the idle.
Same things work on a 4.3 that work on an 5.7L. There are a ton more parts available for the V8 which can be aggravating if you're building a V6.
I build one in a '91 Astro van. Idled like shit but would burn tires like a V8. Cam I used was too big, it has roughly the specs of the old flat tappet L79.
I wouldn't go past teens in .050 duration and a wide LSA to keep overlap down and vacuum up in the intake.
Im looking at going towards comp cams for this build, not sure which cam yet. I am looking to do vortec heads, vortec intake, but keep the stock TBI using and adapter plate as well as headers.

Anything else i should be looking out for? I want to avoid a carb as much as possible.
 

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Discussion Starter · #17 ·
Also, do you think the stock injectors would be fine with those upgrades? I head the 4.3 marine injectors might be higher flow or that i can go with 350 injectors. Just not sure if i even need them or if i do with the above upgrades i mentioned.
 
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