Engine/tranny swap: 86 Silverado

[Orion88]

I came across a deal on Craigslist and I'm thinking about going through with it. A guy has an 87 K5 blazer that is rusted in some bad spots and he is either parting out or selling the complete truck as is. It has a Stage 2 GM Crate engine with throttle body and it has 30,000 miles. Also has a rebuilt 700r4 with 16,000 miles. Truck supposedly has good interior and doors and the transfer case was rebuilt at the same time as the tranny. Asking $700 for the engine/tranny or $850 for the whole truck.

My truck has a bone stock carbed 350 and a TH400 that gets hot when plowing snow. It still shifts and runs fine, but my dad and I were talking about getting it rebuilt or swapping in a 700r4 anyways. Our tranny shop quoted us $900. Overall the truck performs quite well, aside from being bone stock and down on power. Fires right up on cold days, idles smooth, kickdown and electric choke work, etc. It has very good original paint and interior and minimal rust. Definitely not a beater, nor is it a show truck.

So... there are a couple questions I have that are keeping me from pulling the trigger. First off, if I buy the whole truck at $850, how much of that could I potentially recover selling off the interior, doors, top, T-case, and my old 350/th400, and finally scrapping the rest of the truck?

Secondly, how much money will I spend on fluids, spark plugs, filters, engine and engine bay paint, clean up supplies, etc etc?

Third, can I pull the engine/tranny without disconnecting the two and without removing the front end sheet metal/core support from the 86? I know I'll have to at least remove the hood but no big deal.

Fourth, how long should this swap take? I assume a full weekend at least.

Fifth, should I pull the throttle body and put the quadrajet back on the crate engine? I know q-jets are amazing carbs, I just don't know if it will need rebuilt or tweaked for the higher hp engine. And will I be able to use the kickdown/electric choke on the crate engine?

Lastly, does anyone know about these stage 2 GM crate engines? I found two crate engines on summit that were referred to as "stage 2" made by ATK High Performance. One had iron heads and was rated at 325hp and the other was aluminum rated for 375hp. What kind of difference would I see after doing this swap? Is it worth the trouble?

Thanks in advance for the help.

[Orion88]

Update: engine is the 260hp crate engine and it was purchased from a Chevrolet dealer. Also got a couple pics. Not sure I wanna buy the whole truck now but still maybe interested in the motor and tranny.

[Jake Wade]

You really don't know what you got there. The 260hp GM crate engine has perimeter bolt valve cover heads. That Blazer has and came with centerbolt valve cover heads.

Someone painted the valve covers, GM uses black for their crates in that style.

Your carbed intake will not fit without modification, unless it is specific to those 87-95 heads

too many unknowns on that deal

[Jake Wade]

If you mainly use it to plow snow, the 350/TH400 combo is what I would want.

Rebuild your current 350 or buy a crate replacement from GM, around $1500, then you know what you got.

[Orion88]

It's my daily driver and a backup truck in my dad's snow fleet. Rarely actually sees action. I drive it to and ffromcollege so the overdrive would be nice, and some extra torque would be good for plowing. But thanks for the help. I'll probly pass on this one.

[mattybilt79]

You do have quite a few variables here. A 30k motor could burn up just as easily as the motor you have now for any reason including unknown history. So you have that to go with swapping the motor with or without its fuel injection parts or doing the work to swap out the manifold and carb it. You have a 4wd transmission that would need a tail housing swap to go 2wd or keep the transfer case and not run a front driveshaft but might have to make a rear driveshaft work either way due to length issues and crossmember that may or may not need swapped. I personally have no experience with plow trucks but not sure how a 700 would hold up to pushing snow but i know they hate heat but can be built up to do that type of work. If all thats really wrong with your truck now is an overheating issue i would investigate that first. There are a lot of things that could go wrong and other parts to source, having a complete vehicle to get parts from is always a plus and scrapping parting out what you dont need is always a good way to get some money back. Everything could go fine too though there is no telling. Really a question of how much money you could put into it and how much time you can have the truck parked really.