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Need opinions, bought a '87 K5...

7K views 20 replies 13 participants last post by  Beat95YJ 
#1 ·
First off I want to thank everyone here in advance for their help. I'm a long time lurker and finally registered because I made the leap and got what I would call a "real" 4x4. It's tuesday so we all know what that means....stupid questions time. I'll try not to write a novel.

I recently aquired an '87 K5 Blazer that seems to of had some work done. I'm not totally new to the game, my last truck was a lifted Avalanche but I traded it in for a new Jeep for the wife. I bought this truck because I only needed a daily driver for 6 months. I'm constantly overseas and will be back in a week only to be back in 4-6 months. I plan on keeping it as a toy when I buy a real DD. My questions are what do I need to watch out for? Any weak points that I need to go ahead and address? I'm talking short and long term, within the next 6 months and then later. To better give you guys an idea of what I'm working with I copied and pasted a bit from the for sale ad....

It has a 383 stroker equipped with a 4 bolt main, forged pistons (8:1 runs on 87 octane or you could put a blower on it), forged crank, H beam rods, Edelbrock Performer aluminum heads and intake, Edelbrock headers, dual high flow cats with Flowmaster 40 Series mufflers, dual electric fans, 46mm throttle body, oversized injectors, custom chip from TBI Chips, and an 18psi TBI regulator spring. It has a 4" Superlift (no blocks) that still has the stickers on it. The tires are 35" Pro Comp MTs on Eagle Alloy wheels. The paint is dark orange metallic. It has an STC soft top with tinted windows. The interior has been stripped and the floor and rear area has been Herculined. It has a removable Grant steering wheel that fits inside a heavy duty steel Tuffy console. The front seats are suspension seats/racing seats. The door panels and armrests are new reproductions from LMC. It has 6.5" marine speakers in the kick panels and 6x9s for the rear but no stereo. I put the speakers in and of course the head unit went out. The exhaust sounds better than the radio anyway. Dash, seatbelts and rear seat are still blue. The bumpers are custom built by DIY4x and the rear has a swing out spare tire carrier. It also has rock sliders by DPI and is has some blinding bright Hella headlights. The paint is well done but has a few chips and scratches. It looks awesome from a few feet away. There are a couple small rust spots on the rear passenger fender (pictured) but thats all the rust. It was a TX truck. It has been kept in covered parking and out of the elements since restoration. It has not been driven much at all since the rebuild. I lived in Key West a couple years after the rebuild and mainly just cruised it around town and I drove it to work once a week. It sat under the carport while my new car sat in the sun/rain. The odometer reads 086xx. The motor and trans were replaced within 2k miles of turnover but I I dont remember if it was on 98k or 2k so they has between 6-10k on them. The trans is a Bowtie Overdrives stage 2 with a 2000rpm B&M torque convertor. All of the work was done in 2005-07, I have all of the reciepts. The transfer case has a small leak from the rear seal and the rear pinion seal leaks a little as well. 3.42 gears.

So first thing's are the leaking seals. I've already gotten in touch with someone that will help me fix these. I've been told they're fairly quick and easy fixes. After that I will install a new head unit which isn't a big deal and can do myself. I plan on doing a good once over with someone who knows much more than I do. To be honest I know little about nothing. Just wanted some insight from more experienced wheelers on what the next steps to ensure this will be a reliable DD would be. Finally, pics of said truck....







 
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#3 ·
Should've mentioned that. The truck will never see tires bigger than 35's. The truck will see mostly mud with some rocks on occassion. I found out the importance of skid plates quick with my Avalanche. The plastic one from the factory is great let me tell you :shaking:. Bottom line is reliable DD for the most part. As already stated the trans is a bowtie stage 2 OD with 2k rpm torque converter. Basically a beefed up 700r4 from what I understand. I have no idea on transfer case but it was on the top of the list of things I'm worried about. Along with 3.42 gears.
 
#5 · (Edited)
Well to me it looks like someone has already gone over this truck pretty well and should be fine for what your planning on doing. DD/Wheeler...fix your oil leaks and wheel that bitch like it is. You can't change or upgrade one thing like tire size etc w/o having to change components to match it so you aren't over stressing axle's and such. If you stay with your 35's you will be fine. Throw some good lighting on the front of that bumper because those headlights suck, and add a good winch...

With the carriers that are in your diff's you can run a 4.10 ring/pinion, 4.56 and up you will have to change out the carriers front and rear. (Given that they are 10 bolt corp's, by the looks of it they are) Put a Detroit locker in the rear, open carrier in the front with 4.56-4.88's. The 383 should make up for your higher gear ratio you have now for light wheeling/mud.

BTW don't wheel it in the brush! That paint is perdy :D
 
#6 · (Edited)
Great info guys, keep it coming. I'll confirm the 208 transfer case as soon as possible. If someone could point out where I can get started buying the gears (are we deciding it needs 4.56's?) and the rest of the parts that would be great. How much are the gears, lockers, carriers etc going to run and around about time to install? Thanks again for the help.

Someone told me to expect trouble from the steering box and tie rod, can anyone explain what led them to that conclusion?
 
#8 · (Edited)
X2 on fixin leaks. 208 is a decent case. Suggest changing gearing 4:56 or 4:88.
Maybe Detroit rear, selectable front.(air, elec, cable) Beware the skinny pedal with that 383 as you will break shit. Bouncin is bad.
GREAT LOOKIN RIG Not sure about gears but all the lockers seem to run between 500 to 1000 depending. Cheap don't allways get you home.
 
#10 · (Edited)
3.42:1 gears are too high for most cars. I would put 3.73:1-4.11:1 gears on a Mustang. On a truck, a K5 is certainly the real deal, 4.88:1 for 33" and up to 5.38:1 for 38". But I have an AOD which is close ratio, and with your 700R4, that 3.06:1 first gear is a lot lower than my 2.40:1. I think the 200R4 is geared close like my AOD. I am going for low gears, you will probably want to go higher than me with your wide ratio transmission.http://www.4lo.com/calc/geartable.php
 
#12 ·
Really? I have an '89, running 4.88s with 38" tires, and the r.p.m.s are just about right, plus, anything numerically higher than 4.88 is going to have a tiny pinion in a ten bolt axle (front)

Maybe, when he goes to one ton axles, he could run 5.38s.

'course, that's just my .02......
 
#11 ·
I like the TBI setup and the suped up 700 R4 with the 2,000 rpm stall. Is it a lockup torque converter? GM was generous enough to actually put a solenoid and clutch inside the torque converters of their automatics. Ford did not resort to such until they came out with the computer controlled transmissions. I wish somebody would put a clutch and solenoid in a C6 torque converter so I can have the best of both worlds.

You have got a nice truck.
 
#14 · (Edited)
If it were me I personally wouldn't put any new gears and definitely not lockers in until you decide if you will ever want any more from this truck. Maybe just use 4-lo when you are wheeling and don't tow. The axles you currently have (10 bolts) are known for being weak especially in the rear. Yes the current gearing may not be ideal with 35", but any money spent on gear upgrades would be better spent on axle upgrades. While lockers would help you off-road, these axles really are not strong enough to take them reliably.

All that is only if you were wanting to take it farther or if you have trouble with the current axles. There are a zillion old Chevy's running around on stock 10 bolts with stock gears and 35's and they are fine.

Another common problem with this body style of Chevy is the frame can crack around where the steering box bolts on. This is more common once larger tires go on. So check the frame around the steering box for any cracks. If there are cracks, there is an aftermarket weld-in kit to repair them. If there are no cracks but you want to prevent them, there is a bolt-in kit. Check offroaddesign.com.

I agree with the guy that said just wheel as is and have fun. Just make sure the maintenance is current and the fluids, brakes, belts, hoses, and everything are good and drive. That is a sweet looking Blazer.

Edit: another thing I thought of - I don't know if there is one already but a large aftermarket transmission cooler will help prolong the life of your 700 trans. Get the biggest one you can fit. Easy to install should cost you less than $100. Keep the factory cooler plumbed in as well.
 
#15 ·
Switching to tons right now probably isn't going to happen. I know the 10 bolt isn't the best axle out there but I'll admit that this will be 90% mall cruiser for the next six months. After that we can look into upgrading axles. In the mean time I'm strongly considering changing gears to 4.10's since I am in touch with someone that can help me out with installing them. Can anyone think of a reason why the truck has the 2k rpm stall and do I need it? I was also looking to possibly replace that with something lower.

Will be looking into a transmission cooler Pat. That's not the first time I've heard needing one mentioned. Thanks again. Glad to see you guys like the truck.
 
#16 ·
I really like this K5 as it is. If I were to change anything it would be to find a dana 70 right side drop and a dana 70 rear. Then I would put 5.38:1 gears and detroit lockers in them. I would put 38" tires on and call it good.

I really like GM TBI and Howell custom chips. I also really like the 700 r4, and K5 Blazers. Always have.

Another fun idea is to put a 2 speed planetary box in front of a Stack Monster box 3 speed transfer case.

Now I want to put a 400 crankshaft in a 350 block and do the heads right.
 
#17 ·
Find a 3/4 ton truck with 4.10s in the bone yard and rob the axles. The rear will be stronger than yours, and you'll likely be into it less money than an R&P change on yours. Sell your axles and damn near break even.
 
#19 ·
I put a 6 lug sf14b in my 91 k5 with 3.73 gears on 35 inch toyo mts. My speedometer is dead on. Correcting the speedometer was not a concern of mine. I matched the stock gearing of the sf14b with new gears for the front 10 bolt. I was surprised to see that it was actually correct though.

I agree that you shouldn't spend a dime on the rear 10 bolt. My advise to you is to clean that beauty when you do take it out. I don't mean make sure that paint shines in the sun. I mean clean in the wheel wells, underneath, the rockers, back side of the bumpers, ect. Ect. If you don't, that thing will rust out just like all the rest of them. My 91's body is pretty bad in spots. I also have an 87'. It's worse. Possibly gonna get a 88' here soon, and I expect to see rusted out floorboards, rockers, fenders, ect. I expect the only thing to not be rusted to junk will be the top ( k5 humor)

Being as how you have the soft top and no use for a back window, is it even in the tail gate still? And is it electric or manual?
 
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