78 K10 shooting out of 4WD when driving

[Engineer]

Here is what I would check.

There are two hex shaped plugs on top of the NP205. These retain the shift rail poppet balls, and springs. Take them both out to compare to see if either is weak or broken.

If this checks out grab the output yokes and shake them. They shouldn't have any play. If they do you have a bearing out. You may not see any play and still have a bearing out.

BTW, what is this "xgruntusmc" business? I thought once a Marine, always a Marine.....

[momorales511]

Probably a fork inside the case.....there is little plastic tips on the "fingers" of the forks(there's a high and a low) that wear out. Its a pretty easy fix and parts are cheap.

[xgruntusmc]

Thanks, my plan with this is to yank the engine, hot tank, bore 30-40 over, hone it and build it up from there.  Once that is done i'll give it a 6" suspension lift, 3" body and slide 37" IROC SS tires on it.  then through out i'll be picking away at cosmetic issues to pretty things up a little.  the interior needs some TLC, especially the door cosmetics.  it's currently got the stock 350 4BM, it's got a 12 bolt rear with 3.07's but i'm planning on changing the gears to 3.73 before too long.  I'd love to change the bench to a set of buckets but we'll see if that ever comes to pass.  I got lucky though as there isn't a bit of rust on the dang thing to be concerned about as the only rust i've been able to find isn't even big enough to put a pinkie in and that's on the bottom of the rocker.  it's got a new alternator, fuel pump, intake, carb, valve covers, and headers.  since i've been in the military since 2000 i really haven't had an older vehicle that i could work on and that's what drove me to this and i'm slowly picking away at things on it.... Mo and Engineer, thanks for the advice as well, engineer, i'm assuming the bearings you're talking about are the hub bearings correct? (that was actually my next job i was going to take on after i get back from a little bit of business) and "xgruntusmc" is basically implying that i was a grunt in the Marines, i'll always be a Marine, i'm just not a grunt anymore, but thanks and yes you're right, once means always

[Engineer]

The bearings I am worried about are the ones in your transfer case.

If your transfer case is jumping out of gear it almost always means an excessive amount of play somewhere. A loose bearing will cause the shaft it is intended to stabilize to walk.

The NP205 will put up with a ton of abuse. But it does have it's limits.

[Greybeard]

Thanks, my plan with this is to yank the engine, hot tank, bore 30-40 over, hone it and build it up from there.  Once that is done i'll give it a 6" suspension lift, 3" body and slide 37" IROC SS tires on it.  then through out i'll be picking away at cosmetic issues to pretty things up a little.  the interior needs some TLC, especially the door cosmetics.  it's currently got the stock 350 4BM, it's got a 12 bolt rear with 3.07's but i'm planning on changing the gears to 3.73 before too long.  I'd love to change the bench to a set of buckets but we'll see if that ever comes to pass.  I got lucky though as there isn't a bit of rust on the dang thing to be concerned about as the only rust i've been able to find isn't even big enough to put a pinkie in and that's on the bottom of the rocker.  it's got a new alternator, fuel pump, intake, carb, valve covers, and headers.  since i've been in the military since 2000 i really haven't had an older vehicle that i could work on and that's what drove me to this and i'm slowly picking away at things on it.... Mo and Engineer, thanks for the advice as well, engineer, i'm assuming the bearings you're talking about are the hub bearings correct? (that was actually my next job i was going to take on after i get back from a little bit of business) and "xgruntusmc" is basically implying that i was a grunt in the Marines, i'll always be a Marine, i'm just not a grunt anymore, but thanks and yes you're right, once means always

Nobody addressed this the issue of you wanting to redo your engine. While it's yours to do with as you please my suggestion is to leave the bores as small as is necessary to clean them up. Just saying that you want to go 0.030 or 0.040 over is pointless until you know it's necessary. It won't gain you any horsepower if that's what you are after. And it reduces the overall life of the block. They can only be opened up so much and then it gets expensive.

So, another suggestion is to let a respected speed shop or mechanic do all the decisions making on the machine work and you just guide the decisions on what parts to add to it to make it all work together. There is a ton of horsepower to be gotten out of a 350 with the right application of select parts. Not simply the parts that sound cool. With certain flow characteristics of the engine there would be certain improvements to the induction side as well the exhaust side. A four wheel drive used primarily on the street will work much better with more low end torque as I'm sure you already know. So putting a 6 inch tall open plenum intake on 1.88 heads will cause nothing but grief as will using a really large mechanical secondary carb that opens at 2000 rpm on a relatively stock engine. If you like intimate contact with your steering wheel have at it. Having 14/1 compression and trying to use pump gas, using angle plug heads and stock exhaust. These things don't necessarily work well together. I've seen it being done, I've never seen it being done successfully.   

[xgruntusmc]

hey boss, i appreciate the info.  i haven't really toyed around with cars or trucks in about 14 years when i was in HS..lol.. i guess i was always ignorant, but i was under the impression boring out an engine and putting the bigger pistons in there would give you some more power by giving you a bigger engine displacement is that wrong? and as far as everything else goes, i was going to go pretty standard if you will, except for the oversized cam and a set of 200 or 210 heads.  a friend/mechanic of mine who builds race cars and trucks said to expect around 400HP at the crank by doing this.  what's your intake on this? i'm always up for suggestions/opinions because i don't know everything and i like to take other opinions into consideration when talking with others about it. 

[Greybeard]

I certainly don't know everything about an engine but by increasing the size about 5 cubic inches you aren't going to add more than a minibikes worth of power to it. Maybe a couple of pounds of torque nothing to write home about. My 350 is 355ci right now, it didn't make much difference, but add in a nice off-road cam, a good dual plane manifold and a good (read near new) carb and you will have a nice street truck that won't need a diet of regular fuel. Others have alternate and just as effective ways to modify it also. The need for speed needs to be tempered by the fact that it is a 4-wheel drive truck. Guaranteed if that engine gets near 400hp you will start breaking the stock drive train. BTDT. On my old 78 I needed to upgrade to a 14 bolt, a 4.5" drive shaft to handle the extra large u-joints I fitted, beefed up tranny mount, etc. It cascades into throwing money at it. That's no problem if you are up to it. Just sayin. It can be opening a can of worms. The difference is my truck was still popular back in the eighties when I owned before. Parts are much older now and getting a little harder to find. I've been looking around the webz and see there is a bit more aftermarket support these days but except for the custom built stuff I have to wonder about the quality. Aftermarket fenders have cost around $100 for the last 15 years. A good new fender at the time was well over $300 on a good day. Makes me wonder... 

[Irish_Alley]

grey some not all, but some of the price drop is because of people staying competitive now. yes you will lose some quality in cheaper ways to make the parts but its not just one or a couple companys making the parts anymore. but i think you (usmc) will find more power if you stroke the engine and make it a 383. or if you have a 3k budget you can by a engine and be making over 400 hp and tq

[Greybeard]

I agree Irish, with everything you said. I've been out of it for a while so I'm not really well versed on the newer stuff.

I found out the hard way (like I usually find stuff out) that I could have bought a better engineered engine from GM than I made with $3500 dollar investment in sourcing all the parts from my engine.

I think stroking the engine is a good idea on the one hand. On the other hand, I am finding it harder and harder to advocate taking old original iron and making life ending permanent changes to it. Maybe because I'm old. I know they make new cast iron blocks but they don't make new old numbered cast iron blocks.

My block is a 010 side stamped block with a 4-bolt main set. That, I am told, is to signify a high nickle content, hi-po specified block. No big deal maybe, but to me it means a strong block that can handle some HP abuse. Not that I'm going to ever do that but it's capable if I ever change my mind. The is ample cast available down under to assure that it never breaks. Maybe it's inconsequential, maybe not. IDK, what I do know is that if was made in the early years it will never be made again. It might be copied and even improved, but never again will it be made original. 

[roundhouse]

If you want to run 37 tires you're going to be at a minimum replacing the axle gears.  And possibly the entire axle.     If you have. 10 bolt rear axle it will self destruct fairly quickly with a new high HP engine and 37 inch tires

You're go ing to need 3/4 ton axles to run 37s