[HkB115]

I did all the searching and read all about what else was needed, that will not be the topic of this discussion. I'm just looking to find a late model 350 vortec that I can just replace all the seals and gaskets on (MAYBE throw a mild cam and new bearings in) and toss it in place of my worn out 4.3. Prices are all over the place here and the motors are somewhat hard to find, junkyards seem to think they are made of gold. I'm wondering what price range I should expect or ask for on a motor that would fit my description so that I don't get ripped off. For example, I found a 1999 with 120k miles for $900 already pulled.

 

[Gen210]

1st thing to check is the spark plugs they can tell a story. If you can get a camera to attach to your phone you can go in the spark plug holes to inspect each hole.
2nd change the intake gaskets the do leak.
3rd put a new oil pan gasket and rear seal.

 

[kcHotRodtrk]

i have bought two complete vortec 350s in the last year. both happened to be out of early 2000 vans. 300$ for one and 400$ the other. in the baton rouge area.
i have also been a member here since 2016 and this is my first post!

 

[bk2life]

no reason to waste any time with a SBC. LS from the u-pullit yards are $325 complete around me.

 

[HkB115]

no reason to waste any time with a SBC. LS from the u-pullit yards are $325 complete around me.

For me, it's the complexity, amount of time it takes, and how much it will cost. A sbc will be the easiest motor I can put in there, plus I read it puts down the same if not more torque than a 5.3

 

[bk2life]

For me, it's the complexity,

everything you have to change or modify you have to do with an LS. If all you are worried about is torque, than install a bbc. To me, fuel mileage, smoother running engine, way more advanced engine management (computer) and tunability, federal emissions legality and ultimately resale value. It can take you a weekend to swap in an LS. This of course if you know what tools are and how to use them. A sbc will net you maybe 15 mpgs if youre lucky on a good day. An LS will start at 20+ MPGs. You want more power? install a cam. sbc is a great engine, but it's dated, and for swap reasons, there is many more ls platforms being swapped than sbcs because of the immense advancement in technology.

 

[kcHotRodtrk]

For me, it's the complexity, amount of time it takes, and how much it will cost. A sbc will be the easiest motor I can put in there, plus I read it puts down the same if not more torque than a 5.3

If small block is what you know then dont overlook it. pull a part type wrecking yards charge the same regardless of engine family or size. i enjoy 380-420 lbft from 2800-5500 w just a cam, springs, intake swap. fun at the track and around town w a/c to boot. makes good vacuum, stops well, idles clean, and hooks hard. im ok w 15 mpg.

 

[HkB115]

If small block is what you know then dont overlook it. pull a part type wrecking yards charge the same regardless of engine family or size. i enjoy 380-420 lbft from 2800-5500 w just a cam, springs, intake swap. fun at the track and around town w a/c to boot. makes good vacuum, stops well, idles clean, and hooks hard. im ok w 15 mpg.

The way I see it is I can keep my accessories and computer/harness I have, don't have to notch the frame for ac, and still have plenty of room for the custom intake I have. This truck isn't a daily, and sees mostly non-paved roads now, so mpg isn't an issue.

 

[Salty Crusty]

I've seen the internals of a lot of high mileage L31's and have been impressed by how well these things look even after a lot of miles. I'd pull all the main caps and check bearings, same with rods. Most are in great shape even at 150K, but they need to be looked at. Stock pistons and rings should be fine. Add a bigger cam and set of lifters, take a few minutess to clean up the bowls and short turns on the heads and back-cut the valves before replacing springs. Upgrade the injectors. In most cases, these will make 400K+ without too much trouble.
Many LS engines can't be overbored by more than .010. What GM learned from low tension rings, better metallurgy and fuel injection from the L31 and prior TBI engines was applied when designing the LS engines. No reason to have cylinder sleeves that can be overbored by .100 if there's no chance it'll ever be needed except for catastrophic failure. Overhaul at 400K? Hone it .0-10 over, slap it back together and send it. Most L31's outlasted their trucks, same as LS engines do now.

I have a few S10's in my stack lot, all 98 & up. Everything with a V6 will get an L31 or stroker version of it. Everything with a 4 banger will get an LS. I don't see any reason to mess with a 5.3 when a 6.2 is soooo much more engine and has soooo much more potential. Shame they're so dang tough to find but I do come across one from time to time.

I've bought a few good L31's complete, $400 - $750 under 100K miles.

 

[chevymec]

If you didn't hear it run, don't give much for it. Most L31's around here have knocking bottom ends or cracked heads. Just remember if you add a cam, tuning will be needed and the black box pcm isn't the best for that.

 

[oldeerslayer]

98-00 are easy to swap the black box for an 0411, since the 01-02 S-series had them. A guy named Lextech has Excel spread sheets available for swappin 98-00 4.3 to the 0411 PCM. PM me if you want his email addy. You just put an 01-02 Express van tune it the 0411 if you stay stock. Or use it as a starting point for a custom tune.
I also have the black box pin out for the L31 injectors or you can look at any 98 1500 305-350 wiring diagram.