350 or LS

[Zelph]

Non existent aftermarket support when compared to an LS/LT.

 

[Cruck]

My estimate on LS swaps used to be $2000 plus the cost of performance or maintenance parts, plus the cost of transmission but including a junkyard 5.3. That would at least get into the ballpark. Now, thanks to inflation etc, I think you should probably start at $2k plus your engine and transmission costs, assuming you are going for stock power level (and there's ZERO wrong with that).
Baffled fuel tank and new pump/sender, something like nylon fuel line or making the factory hardline work, a reworked factory harness and modified tune for VATS and various delete (again, does not include performance tune), adapter plates, and misc pieces for hoses, intake tube, radiator, cast iron manifolds, etc. That's probably an aggressive budget for most, but other guys are going to say that they did the same swap for less than $1000 all-in, so I think it's fair. That's no labor, used/wrecking yard parts, and not much in the "might as well do this" category, but it will get you running and driving just like the 180k mile Yukon or whatever you pulled it out of...

When you look at swap budget breakdowns, you really need to look at it from a Required/Performance/Looks breakdown. If you want it to look nice, then you are going to add $500-1000 for breaking the engine down, cleaning everything, painting the block, reassembling with new gaskets, shaving the factory intake manifold, nicer filter setup, braided fuel lines, etc. If looks aren't a major factor, then most of the parts attached to it in the junkyard will do just fine, just spend a couple minutes with a can of Gunk to keep your hands cleaner while you work on it. That money isn't part of the swap, it's part of dressing the engine up.
Same for performance, if 300 hp is fine, grab any 5.3 and have fun. Some folks will have $5k in cam/heads/intake/headers etc. and call that part of the swap cost, where it really isn't. Making a plan is critical, most $10k+ swaps will have had a point in them where the owner changed their mind and subsequently had to re-buy parts because something didn't work with another part of the build, or a case of the "OOOOH! Shiny!" hits and they ditch the 4L60e they just built up for a T56 or something like that. Of course those can happen, and can be a good change. But don't let the total budget for something like that scare you, that's a Change Order in the business, and should not affect creating an initial budget that you plan to stick to.

If you stray farther and go into "non-standard" swap engines, you will be in uncharted territory. It's entirely possible that the factory manifolds from the Camaro V6 will fit in a truck chassis, and simultaneously possible that no combination of anything previously made will clear in your truck, and a $2000 set of custom mid length headers is the only option. Same for transmission options, maybe you can stab a regular driveshaft in and be good to go, or maybe you have to find a driveshaft from a 2008 Solstice GXP and mate it with a 2004 ElDorado halfshaft to make things work, and it's hard to say before you just dig in. Obviously I'm just making that up, but the point is that you don't know what you don't know on a one-off swap.

If you like the thought of a 6 (and who doesn't, especially if the truck was originally a 6 anyway) check out the Vortec 4200 straight 6 from the Trailblazer. It has a little more aftermarket support for swaps, and can make similar power to stock 4.8/5.3. There's a few folks running them in square's, but it would still be on the front edge of things. There is more support for the swap in general than for any modern GM V6's, but still much less than for a V8. Being a truck that was designed for a straight 6, I wouldn't think you would have too many fitment issues, but part of the fun is finding out...

Thanks for all the information. I just have a lot of decisions to make and don't feel that I have enough data and knowledge to make them clearly. This truck will not be a daily driver but it will get driven regularly. When I ask folk that have more knowledge and experience than I do they keep telling me to go with a 383 stroker with tbi or a 5.3 ls. Those are both great options but mpg would be somewhere around 10-12. I know that is not what I want. A monster of an engine sounds great but not high on my list. Spinning the tires would be fun but again not a priority. I want when I get in it, it starts up and gets me where I want to go while not having to stop at every gas station along the way. That is how I got to the 6 with 300+ hp and 20+ mpg.

What I am understanding that you are saying is the V6 might work no problem and it might be a total pain. It might be easier with better support to go with a straight 6 with a few modifications I could be in business.

 

[DoubleDingo]

Thanks for all the information. I just have a lot of decisions to make and don't feel that I have enough data and knowledge to make them clearly. This truck will not be a daily driver but it will get driven regularly. When I ask folk that have more knowledge and experience than I do they keep telling me to go with a 383 stroker with tbi or a 5.3 ls. Those are both great options but mpg would be somewhere around 10-12. I know that is not what I want. A monster of an engine sounds great but not high on my list. Spinning the tires would be fun but again not a priority. I want when I get in it, it starts up and gets me where I want to go while not having to stop at every gas station along the way. That is how I got to the 6 with 300+ hp and 20+ mpg.

What I am understanding that you are saying is the V6 might work no problem and it might be a total pain. It might be easier with better support to go with a straight 6 with a few modifications I could be in business.

The 300hp v6 with 20mpg is for a car. It'll never work the same in a truck. You want reliable, stick with stock or slightly upgraded. It came with a 6, a straight 6, no comparison between a v6 and straight 6 except cylinder count.

 

[Shorty81]

Maybe you would be better off in a modern truck.

 

[Hunter79764]

What I am understanding that you are saying is the V6 might work no problem and it might be a total pain. It might be easier with better support to go with a straight 6 with a few modifications I could be in business.

That's my take, but beware that the 4200 swap is not a fully baked option either, there will be trial and error and discovery along the way. The harness and electronics should be available from a few places (one is linked below), but the oil pan needs to be figured out, same for exhaust and mounts. Use a 4l60e that it came with and that will simplify things vs trying to mate it to anything else, if you NEED a stick, the Colorado inline 5 was mated to an AR5 5 speed that should bolt up, but your tuner needs to know about it before you get the harness done. Fuel system needs basically the same setup as an LS swap, '87 tank and sending unit with 55 psi pump, need to confirm if the engine is regulated on the fuel rail or externally regulated and requires a Corvette filter/regulator. Plus a dozen other small things...

Conversion Harnesses | Lime Swap

Wiring Harnesses for Engine Conversions

www.lime-swap.com

 

[Grit dog]

Great post by @Hunter79764 !
What it taught me is the old saying always holds true. “cheap, fast or good, pick two!”
Also has me solidly leaning towards a small block or big block tire fryer when the time comes for the ‘77 and not a LS.