Home Forums Gear Hunting Trucks and Four-Wheel Drives 84 K5 Blazer motor/trans replacement options

I’m looking at buying a fairly clean 84 K5 Blazer. The body’s pretty straight, there is some rust that can be fixed by cleaning and glassing it, and most of the electrical works. It’s got a 327 in it now with a 700R4 trans. The motor has some issues, and the trans is original and hasn’t been rebuilt. It prefer to just yank them both out and replace them both. I can do that myself, but I wondered what options you guys thought best while on a budget. Ive found a few rebuilt 350’s with rebuilt transmissions for +/-$1500. I don’t need a hot rod but mainly just a somewhat reliable vehicle my son can drive when he turns 16 in 5 or so years. I want to use this as a lesson for him in working on vehicles.

Other plans would be to clean and repair rust spots and a couple small dents, then coat the whole vehicle with Raptorliner. Do the little bit of time consuming, but not overly expensive repairs inside. And then just drive it. Possibly replace the hard top with a soft top. I can buy it for less than $3000 as it sits. Probably closer to $2000. I figure I should have less than $5K in it once everything is done and back to working order.

What/where do you suggest the motor/trans search? What would you put in it if other than what I named?

Swap a LS into it. An 80-120k 4.8 or 5.3 would be outstanding in that K5. Could even use the same transmission and if you are allergic to messing with electronics and high pressure fuel pump ect, put a LS MSD in it with a carb intake. A lower mileage 5.3 pullout with the harness and if you are a crazy person you could go nuts with a computer controlled complete system.

Holley Terminator Max is a real easy to use system with great help on line.

I would LS swap or put a TBI 350 in it. It sounds like a really cool truck, one I would want myself. That being said, you may be able to buy a newer Tahoe for not much more and get the safety features like ABS, crumple zones, airbags, etc. It seems like used Tahoe’s are pretty cheap around here.

I've had 3 Chevys with the 700R4 transmission. All 3 had to be replaced at about 120 to 130k miles.

that's why I QUIT driving GM vehicles...

I’ve been thinking about an LS swap. That could be an option. With the trans having as many miles on it as I think it does i don’t expect it to last a whole lot longer. I like the newer Tahoe’s as well, and I have a 2018 in the driveway as my company ride, but I want something that you can pull the top off of like a big Jeep.

A bit out of the box and not nearly as sporty, but, how about a 4.3L V-6? Just a thought as they put them in full-size pickups and vans for at least a decade.

Swapping in another small-block is going to be the simplest in terms of fitting right back into place.

I like the 700r4 myself. Putting a tall set of tires on those trucks that usually came out with crazy high gears killed a lot of transmissions. A good remote trans cooler can help a lot, as well as overriding the lockup torque converter switch to keep the converter from locking. That damn thing locking unlocking all the time is another trans killer.

What kind of issues does the 327 have? I loved those engines. Not the torque of a 350, but so smooth, cammed correctly with a good carb & they're wonderful off road engines. They haven't been made since 69 & are getting hard to find. I wouldn't recommend scrapping it or giving it away until I found out what it originally came out of.

I wouldn’t scrap it, but may rebuild it and sell it. There’s some serious noise coming from it that sounds like valves. It’s got an exhaust leak and the alternator belt squeals so it’s a little hard to discern exactly what it is.

OK,
The k5's can be a great little adventure 4wd if you care to put some minimal money into it, and a bit of labor.

Though not original to that year model, keep the 327 and have the block inspected by a machine shop. An sm465 four speed and np-205 Should be easy to find from a donor rig.

The one ton axles of the same era, are a direct bolt swap as well. It starts with a donor rig. The one ton square body trucks went to 1991 I believe.

A cheap reman quadrajet carb should get yah up n running. EFI will do nothing for you but cost money. You're not climbing mountains or operating in below zero weather. It's Oklahoma.

Some of the best donor vehicles, the m1008 cucv. Hydroboost brakes, Dana 60 with limited slip, pto np-205 transfer case, 14 bolt rear with Detroit locker. 4:56 gears. Heres the donor vehicle for my 68 k20, got it for real cheap:

Well, I got it bought last night, and I’ll go pick it up this morning. I’ve figured out a couple of issues that may be causing the motor to seem worse than it is. The main one is someone used a homemade bracket to hold the throttle and trans cable. It’s not well made and so the cables are at an angle and you can barely give it throttle. It also jacks with the shift points. I’ll either order one or see if orielly’s has one this afternoon. That’ll be the first thing I work on other than adding fresh gas. Then it’s changing the transmission pan gasket to it’ll quit pissing in my driveway. I don’t think I got a bad deal for $1800 even if the motor and trans need to be replaced. We’ll see I guess!

Remote tranny coolers and locking the tranny in 3rd until up to highway speeds was all that had to be done with those transmissions.

Dad had 1 that was still going at over 300k and another that finally gave up at about 215k.

Find a pullout LQ4 6.0 or a 5.3 and the 4l60 or 65E.

Sell the 327.

OK, congrats! A great deal you got. I hope you get lots of hard work put into it. They make a very affordable rig to work on. This company sells great square body chevy stuff:

https://www.offroaddesign.com

Awesome, thanks for the link!

OK,

The k5s are really fun rigs. I got ah mean 67-72 bug though, which is slightly older body style, but big time parts commonality to your rig. I have 3 72 k5s and one title. I'm building a 292 powered 72 k5. Just pulled a 292 inline six from a 1985 truck. Pulled the head and cylinder bores look perfect.

Will keep the front dana 44, and pull the c-clip 12 bolt rear axle for a detroit locked, eaton ho52 full floater. The th350 auto will probably get replaced with an SM 465.

Nice project mainer.

I actually prefer those to the square body, but the square is growing on me.

Clutch pedal and a manual trans would be priority 1. SM465 is super common and cheap, something with overdrive less so. Not a huge vehicle with huge towing capacity, so perhaps a NV3500 would work. Nice to have a stick for service roads and such, and good for a kid to learn to drive one. Off the top of my head, donor vehical peripherals include clutch pedal (which may be an assembly with brake pedal), z-bar, linkages connecting pedal to z bar and z bar to clutch fork, clutch fork, bellhousing. Throwout bearing, flywheel, clutch and pilot bearing should all be available cheap from parts store or Jegs or whatever. Some or all of the donor vehicle stuff might be available aftermarket as well for not much $$. You can go a long ways toward a manual swap with the $$ involved in an auto rebuild. Driving an older gm vehicle with an auto is about as inspiring as eating paste.

Engine-wise, I'm not sure that newer blocks would have the provision for the z-bar stud in them. Your 327 should. A basic 327 or 350 rebuild with 9.0:1 compression and an isky mega 264 cam and a carter or edelbrock 4-barrel carb would be very basic and entertaining. A bit of $$ will get you a set of new GM vortec heads (with hardened exhaust seats) and a matching low-rise 4bbl intake.