84 k10 silverado engine decisions

Hello I am new to the forum. I am wondering which engine to put into my truck. It is an 84 k10 silverado 4x4 with a turbo 400 and previously had a 305. The 305 has gave up so I have the choice between a 350 out of 95 k1500 which needs to be rebuilt possibly bored over and a 6.5 turbo diesel from a 93 k3500 the 350 is $200 and have to pull and the 6.5 is $200 and I will have to pull. Mpg is not a problem. Just looking for reasons to swap one in instead of the other

Welcome aboard

The 350 is nearly a direct swap, even if it’s a Vortec, while the diesel requires a lot of changes. Are you looking for an interesting project, or a quick replacement to get back on the road?

I don’t think I would use the diesel for a quick swap unless I had a squarebody donor vehicle, since many of the non-engine pieces from a ‘93 will be different.

Bruce

This is to be a project. If I use the diesel it will be converted to completely mechanical

Even with the turbo, you might be disappointed with the power. You can improve it, but I’d see if I could drive a turbo 6.2/6.5, and if you don’t like it, you have your answer. It’s gonna be dead simple, and the torque is not horrible, but I’d expect the peak horsepower as it is now to be comparable to your now deceased 305.

With the 350, you can take the whole engine harness and run it TBI, but I’d probably put some much better heads on (TBI heads suck), do a new intake, roller cam and accessories, and run a carb. You could easily have a good 350-400 peak hp/ft. lbs. torque daily driver going this route that would slightly out torque and greatly out horsepower the 6.5. Plus, the 6.5 short blocks are a little bit problem prone. I think I’d build a turbo 6.2 with maybe some 6.5 parts before doing a 6.5, but I far prefer the 350 over either. Even a two bolt main 350 can handle some serious power.

What's your budget? You might spend as much rebuilding that '95 350 as you would buying a new basic Goodwrench 350 crate engine. It may not be high performance, but I have installed at least 3 of them over the years. And with a small 4-bbl and dual exhaust, they work great in pickups and cruisers. It will make even a new 305 feel like a 250 six cylinder.

https://sdparts.com/i-24080894-gm-e...h-new-small-block-chevrolet-crate-engine.html

Notes: A 350 from a '95 truck may or may not be machined for a OE-type roller cam. Also, Vortec heads first appeared on 96 pickups. And regardless of the head type, they may have hairline cracks.

MikeB said:

What's your budget? You might spend as much rebuilding that '95 350 as you would buying a new basic Goodwrench 350 crate engine. It may not be high performance, but I have installed at least 3 of them over the years. And with a small 4-bbl and dual exhaust, they work great in pickups and cruisers. It will make even a new 305 feel like a 250 six cylinder.

https://sdparts.com/i-24080894-gm-e...h-new-small-block-chevrolet-crate-engine.html

Notes: A 350 from a '95 truck may or may not be machined for a OE-type roller cam. Also, Vortec heads first appeared on 96 pickups. And regardless of the head type, they may have hairline cracks.

Click to expand...

Good advice

Not to worried on budget but did not want the hassle of swapping a duramax or ls drivetrain into the truck. I am currently restoring the whole truck from the ground up while it's apart. I have had two other trucks with 350s a 85 k10 and an 83 k5 and have driven a few k30s and 3500s with the diesel but cant decide whether to go with the tried and true 350 or go diesel just for something different
I would like to put something in the truck you would have found swapped in 30 years ago

Seems to me like dude has a ready rebuttle for everything and he WANTS the diesel.
Why bother asking us if your mind us made up?


I vote to rebuild the 305. How's that junior?

if ya want a heavy, stinky, underpowered diesel. just go buy a running diesel. lots cheaper that way. last thing i would want is a dead diesel on the side of a highway far from home.

im for the crate motor or just rebuilding the 305. 305 had close to same tq as 350, lasted as long, and got better mpg. and idled and ran smoother!

Welcome to GMSB from Virginia

I did a L31R Vortec 5.7 swap in my ‘78 K20 and I would do it again. No regrets. Simple swap, durable with 4 bolt main caps, plenty of power, and good value.

https://www.jegs.com/i/Chevrolet-Performance/809/12681431/10002/-1

Let's look at specifications for 1981 to 1986 engines in trucks with a GVWR rating of less than 8500#. There are other versions of both engines, but these are the ones with the highest torque ratings in 81-86.

305: 240 lb/ft torque @ 2000 RPM
350: 275 lb/ft @ 1600 RPM

So the 350 has 35 more lb/ft at 400 RPM lower. And I'd bet it's around 20-30 lb/ft better at 2500-3000 RPM.

1987 trucks got TBI and more torque at higher RPM.

305: 260 lb⋅ft @ 2400 RPM
350: 295 lb⋅ft @ 2400 RPM

Strange that both peak at 2400 RPM.

All said and done, it looks like a 15% increase in displacement gets you about a 14% increase in peak torque. And the 87 engines must have had better heads, bigger cam, more compression, or all three to gain 20 lb/ft over the earlier engines.

I found the above specs here: https://en.wikipedia.org/wiki/Chevrolet_C/K

chappy78 said:

I did a L31R Vortec 5.7 swap in my ‘78 K20 and I would do it again. No regrets. Simple swap, durable with 4 bolt main caps, plenty of power, and good value.

Click to expand...

Didn't notice HP and TQ ratings, but with a similar intake, carb, and exhaust, they're probably around 15% more than the base 350 Goodwrench engine I mentioned above. Which fuel pump did you use? How about carb and intake manifold?