Engine swap 98 vortec in a 83 k10

[Grim]

So recently I have blown the 400 small block in my 83 k10. Being a father a two young ones i dont have much to throw into a new engine for my truck. But recently stumbled across a totaled 98 with the 5.7 vortec with only 78k miles on it. I wanted to hear some pros and cons of the 5.7 vortec.

 

[andy396]

It’s a great engine. It’s the best 350 Chevy ever made. It’s what’s in my boat and I’m very happy. You’ll need one of these:

https://www.jegs.com/i/JEGS/555/513002/10002/-1

Keep in mind though, it’s not likely to make the same torque your 400 did. So set your expectations low and you’ll be fine. Put your 400 crank in it, assuming it’s still good, and you’ll get closer but the cost to turn it into a 383 will be substantially higher than just bolting in the Vortec as is.

 

[andy396]

Oh, and you’ll have to figure out a fuel pump solution as the Vortec block won’t be able to drive a mechanical fuel pump without a cam change and some machining on the block.

 

[97K1500Silverado]

I have a 1979 k10 with sbc 400, turbo 350 3 speed trans and 3:73 gears in 33” tires. Also have a 1997 vortec 5.7 with 4l60 and 3:73 gears on 33” tires.

Vortec seems to have more power all around, better getup and go and also pulls throughout rpm range where the 400 would just make noise above 4K rpm.

Stock hp and torque specs

400 sbc (ratings from 1979 8.5 compression ratio)
195 hp
300 tq

350 vortec
255 hp @ 4600
330 tq @ 2800

 

[andy396]

Good call, I wasn’t thinking his 400 might be stock.

 

[kennythewelder]

X2 on every thing Andy said. If you have the donner truck, you could take everything from it, but the 98 has OBD II ECM running the engine management systems. You ether need to use the ECM from the 98, along with all the wiring, or swap it over to carb as Andy said. You can feed the carb with an electric fuel pump, and you will also need a HEI distributor, that you can swap from your truck. It only takes about 12 PSi of fuel pressure to run a carb I think, but the 98 takes just over 60 PSI and the fuel pump is in the fuel tank on the 98. You could use that fuel pump, and tank on your truck, but you will need a fuel pressure regulator to drop the fuel pressure to IDK 12 to 14 PSI maybe.

 

[Hobie]

@kennythewelder 12-14psi sounds pretty high on the fuel pressure, I've got fuel pressure set at 9.5 psi on the B-mod dirt car that I mechanic for, and it's making around 400hp at the crank. Now I dont think theres a set pressure to be at, but I would think 8 ish psi would be plenty for a carb'd vortec with maybe a 500cfm carb. But every engine is different, and one may like 7 psi, and another identical engine could like 13 psi. Hard to say until you get it in and set up

 

[kennythewelder]

My numbers are just a guess. As for a carb, 600 is about rite. Nothing bigger than 650 CFM for sure. Like you said, every engine is different. There is a math formula to figure out CFM, by engine displacement, and RPMs. I dont remember what the formula is though. A quick search should pull it up.

 

[L31MaxExpress]

My numbers are just a guess. As for a carb, 600 is about rite. Nothing bigger than 650 CFM for sure. Like you said, every engine is different. There is a math formula to figure out CFM, by engine displacement, and RPMs. I dont remember what the formula is though. A quick search should pull it up.

My suggestion is a Q-Jet. The basic carb was used on everything from a 3.7 4 cylinder to a 500 V8.

 

[PlayingWithTBI]

There is a math formula to figure out CFM

For a 350 @ 6,000RPM a 650 CFM carb will work.

https://www.tciauto.com/racing-calculators