NTC 350 Turbo VT50 Rebuild kit?????

[wcuhillbilly]

Got the NTC 350 from a 77 OTR truck yesterday. Thing supposedly has a rod hangning in it but I find no damage to the oil pan or block, need to pull the pan and look. I bought the thing from an old farmer for the turbo setup, aftercooler, and the 25A Jake setup. so for $200 I aint out much if the bottom end isnt rebuildable.

So, Im pulling the above setups and cleaning the surface rust/gunk off, The turbo is a AR12600 or VT-50. I took it apart and found the square bearing retainer plate/bearing is stuck to the compressor side of the shaft. I soaked it in Kroil last nite and will attempt to work on it some more tonite. Does anyone know much about these old snail shells???? Namely, what to watch for or tricks to dissasembly, Is there a rebuild kit availible.???????

 

[topo]

For $200 you have a good start take pictures . With used Cummins engines any thing is possible . one truck I drove had a 290 small cam It was very durable engine but a little slow .The owner pulled it to rebuild and turn up the power and found out there was no rebuild kit for it the engine was made from other parts engine. So it was put back together and ran for another 4 or 5 years that I know of . It was just not worth what he would have in it .

 

[wcuhillbilly]

For $200 you have a good start take pictures . With used Cummins engines any thing is possible . one truck I drove had a 290 small cam It was very durable engine but a little slow .The owner pulled it to rebuild and turn up the power and found out there was no rebuild kit for it the engine was made from other parts engine. So it was put back together and ran for another 4 or 5 years that I know of . It was just not worth what he would have in it .

Hoping to be able to rebuild the bottom end of the 350 and pull parts from my 250 to make a complete engine. This 350 was supposedly pulled due to a rod knock or (they said it tossed a rod). the guys son had all kinds of logging equip at one time and they are both world class cobblers of crap. booger welds and modifications that most of us would only shake our heads at. either way they pulled the engine and got a crate engine to replace it. this 350 was stripped of anything that the crate engine didnt have.
If the bottom end isnt good then I will just put these heads/jakes/turbo setup on my 250 in the M816. but I would like to have the whole 350 in there.... Would it be possible to use the 250 crank in the 350 block if the 350 did toss a rod,???????

 

[wcuhillbilly]

Got a jake and the aftercooler pulled last nite... the jake is scuzzy but the residual old oil looks to be doing its job... good cleaning and a jake kit and this should be ok... the aftercooler looks intact, will pull it apart soon and have it pressure tested...
Turbo is still pretty sad... the housing on the compressor side has a crack in it. and the drive shaft bushing is seized to the shaft.. busted the flange trying to seperate the two last nite.... Should I keep the VT50 or source a HT3B ????????

 

[rangereter]

Is that 350 a big or small cam? If it is a big cam, I don't think the heads would work on the 250. There should be a ton of used turbos out there though.
Regards, Bob

 

[wcuhillbilly]

according to Cummins its a small cam NTC 350, Big cam was usually cast into the block and I havent run across any casting that resembles those words.

 

[wcuhillbilly]

Talked to Blaylock turbo in KS and they will sell me a turbo cartridge for around $300 for the VT50, rebuilt and ready to install on my snail shells. The local yard here had a BHT3B used on a core engine he wanted $400 for plus my locked up core for replacement on his engine that was going to a core company,,,, I thought that was too much, would like to use the HT3B for ease of finding parts, but $400 plus a kit and Im headed towards $600 and alot of bench time for me puttin it back together. Swap of the VT50 will be cheaper and easier in the long run.

 

[WillWagner]

Holset is a better turbo than the VT50. They, the VT50 are known for constantly pushing oil into the intake. The only thing you should need is a drain line conversion and an adapter for the pressure line.

 

[wcuhillbilly]

Holset is a better turbo than the VT50. They, the VT50 are known for constantly pushing oil into the intake. The only thing you should need is a drain line conversion and an adapter for the pressure line.

Yes, Will... I would rather have the Holset, however this salvage yard guy is a slickster, I will likely rebuild the VT for now untill I can find a good ht3b that I can go through in my spare time...
Now I just need the reassembly specs for this jake head that I have scattered all over my bench. Pulled the installation manual off the Jake website the other day,, but its gonna take some arse scratchin to figure out how to put it all back together as my nice pretty layout got knocked over. and I dont remember how many turns per the set screws...
Would like to eventually either swap the heads and pump from the 350 over to the NHC 250, or rebuild the bottom end of the 350 and drop it in... If I do swap heads/injectors over to the 250, I will try to pull the button out of the 350 pump and swap it into the 250, as the ressurection status of the 350 pump is questionable.

 

[WillWagner]

Heads won't matter, they are the same. To put the 350 injectors in the 250, you need to find out if the cams are the same, the cam is another one of those CPL or performance parts. As for the jakes...turns out? What mean that? They are set with a feeler gauge to .018. You do realize that you will need to change out the exhaust cross heads?

 

[wcuhillbilly]

Heads won't matter, they are the same. To put the 350 injectors in the 250, you need to find out if the cams are the same, the cam is another one of those CPL or performance parts. As for the jakes...turns out? What mean that? They are set with a feeler gauge to .018. You do realize that you will need to change out the exhaust cross heads?

I was refering to every little set screw in these jakes has been removed, seals, plungers, oil passages, clips etc. the center actuator has a set screw that comesup from the bottom and I had to continually tighten then loosen to get it and the actuator out, thus the factory setting of X turns in or out is lost. Now that all the rust and gunk is out the housing is nice and clean so reassembly will be alot nicer than dissassembly. I have two more to dissasemble so push comes to shove I will figure it out.
In swapping on the Jakes, I intended to swap the 350 rocker boxes on so that I wouldnt have to grind the arms of the 250. I dont really have the time to do the tasteful rendition of the body work on the 816 hood for the jake clearance right now so I intended to just do the rear two heads.
The NHC 250 has a CPL of 026 and the 350 NTC has a CPL of 016 ,,,, So is this gonna be trouble??????
What do you mean by the exhaust cross head????? I am swapping the exhaust manifold and intake manifold from the350 to the 250...

 

[WillWagner]

By actuator, you mean the solenoid in the center of the housing? if so, they aren't meant to be disassembled. They are removed from the jake housing from the top side by removing the little hold down.There are no factory settings on them. The only adjustable part is where the mechanic sets the lash at the crosshead. The crossheads are the parts on the head that let a single rocker lever depress two valves. The exhaust crossheads are wider on jake applications so the feet on the master pistons can open the exh valves. If you don't change them, the feet will go around the non jake crosshead and the brakes won't work. did you get the throttle switch from the donor engine? how 'bout the clutch switch?

 

[wcuhillbilly]

By actuator, you mean the solenoid in the center of the housing? if so, they aren't meant to be disassembled. They are removed from the jake housing from the top side by removing the little hold down.There are no factory settings on them.
Good to Know

The only adjustable part is where the mechanic sets the lash at the crosshead. The crossheads are the parts on the head that let a single rocker lever depress two valves. The exhaust crossheads are wider on jake applications so the feet on the master pistons can open the exh valves. If you don't change them, the feet will go around the non jake crosshead and the brakes won't work. did you get the throttle switch from the donor engine? how 'bout the clutch switch?

so by bringing the rocker boxes and jakes from the 350 over to the 250 should prevent this.????

its been a few weeks since I had the valve covers off the 350, I may have to go refresh my memory as to what it looks like in there...

I did not get any switches with the core engine, I have the local ( 100miles away) looking for switches in there spare time. I can wire up something when it comes down to it. the schematics are pretty simple with the 3 position on off, and a couple momentary switches on the throttle clutch....

 

[WillWagner]

Prevent what? A tune up? No, you will still need to re set the overhead. The boxes will bolt right up to the NHC, overhead set is the same as described in the sticky.

As for the cam, they are the same for both as are the injectors. When you turbo an NHC, you should change the timing to CPL 026T specs, from timing code E-.0290 to CF-.0383. The 350 CPL 016 is timed at D- .0360

 

[wcuhillbilly]

Prevent what? A tune up? No, you will still need to re set the overhead. The boxes will bolt right up to the NHC, overhead set is the same as described in the sticky. ( I was refering to the crosshead that you mentioned on the previous page)

As for the cam, they are the same for both as are the injectors. When you turbo an NHC, you should change the timing to CPL 026T specs, from timing code E-.0290 to CF-.0383. The 350 CPL 016 is timed at D- .0360

Ive read the sticky on the valve adjustment but without opening up the rockers and visually looking at it all, it didnt make much sense,(im visual and hands on learner, Thus no pictures no understand) I know how the engine works, but the "I" "V" and knowing what kind of injectors I have is the confusing part) I will open the boxes on the 350 soon as they are as gooey as the Jakes in the pics, and in dire need of cleaning. Just dont have any time right now. One Jake housing is cleaned and painted, ready for the tune up kit and cleaning of the actuator and plungers. A second Jake is off and enroute to be cleaned and blasted. The third is still on the 350... The 250 is running good and I dont really want to open it up untill every thing is ready to bolt on. Got to extract a ranchers truck from a creek tomarow evening, thus need the wrecker to keep rolling as much as possible. Going to Cummins tomarrow to pick up the rest of the intake/exhaust/turbo gaskets. Still need to come up with $300 for the VT (for now,, may have a line on an NOS ht3b from a guy who bought a bunch of old inventory.

Will, aside from the TMs what Cummins book do I need to find for rebuilding this 350 from intake to oilpan. cold setting injectors/valves/timing/crank/cam etc.????

BTW, is there an updated fuel cross over between the heads, specifically the flat screws that hold them down.. with the rockers/jakes/vavle covers, its along way down there, and Im thinking an allan or torx bolt would be better than the flat slot sir strips alot.

 

[WillWagner]

No update on the fillister head screws for the jumpers, they were the same 'till the N14 stopped production in '02. A long #3 flat head screwdriver works well.Use one with a bolster, works better. PM me for info on the manual, I think I might have one.

 

[wcuhillbilly]

Got one jake rebuilt !!!!!





The before and after and nite and day. the dirty head in the pics is the cleanest one of the three.
Rocker boxes and the other two jake heads are at the machine shop getting tanked and blasted. Cant wait to get these mounted and working.
Do believe the NTC 350 will become scrap as the vavle galley has substantial rust/corrosion build up. Fought with it for an hour to get 3 injectors out, sacrificing a Snap-On screw driver and some of my dermis layer. Plumb shame, the NTC has the decompression lever on the front of the block.

 

[jarhead1086]

When you turbo an NHC, you should change the timing to CPL 026T specs, from timing code E-.0290 to CF-.0383. The 350 CPL 016 is timed at D- .0360

I will do some more reading an educate myself on what you just said to do. Thanks for your help and sharing your knowledge. I hope to fire up my turbo'ed 250 in the next couple weeks after I get my new coolant tank welded up and installed. What does this timing change do for you exactly? Would it hurt anything to run it to the stock timing while I work on other gremlins? This 250 started easily and purred with the dual fuel line before I added the new Holset. Hoping this is still the case. I want to take extra good care of this girl.

 

[wcuhillbilly]

I will do some more reading an educate myself on what you just said to do. Thanks for your help and sharing your knowledge. I hope to fire up my turbo'ed 250 in the next couple weeks after I get my new coolant tank welded up and installed. What does this timing change do for you exactly? Would it hurt anything to run it to the stock timing while I work on other gremlins? This 250 started easily and purred with the dual fuel line before I added the new Holset. Hoping this is still the case. I want to take extra good care of this girl.

Ive been on hold for several weeks working on house related stuff. but I did manage to get another jake put back together the other nite only to test the solenoids for the jakes and find they arent up to par. new one from Cummins yesterday was $103.
Got a rebuilt Schwitzer 4LHR turbo in the mail last week, just needing time to pull the wrecker down for a couple days. Been reading on the dual fuel, and alot of guys are using brake line for the line. My donor engine has the line, but I will be using JIC or AN fittings with flexable line as I used brake line on a feeed line for a turbo on a 6.2 once, and a $.50 fitting cost me $3000.00 in repairs due to the vibration of that line.
I am curious about this timeing thing as well, when all these pretty parts go on mine, I want to be able to dial it in right, as 19 tons is a heck of a rolling road block. What fuel button (idle spring plunger) do I use.......

 

[jarhead1086]

It's been tested and with the exception of a couple minor coolant leaks its good to go. The boost was 5 ish, but got it over 10 on a little hill without load. EGT's dropped almost 300 F, really happy about that. The turbo and rear exhaust made the cab quieter so I can hear turbo better. I still need tranny shifting tweaked in and the timing adjusted. One thing at a time. I also plan on putting the intake cooler on its own closed system to get the coolant another 100 F colder than engine coolant. Just curious to see what it does, if anything, and having fun learning. Still starts easily. So far so good. I can't download pictures right now, just get the spinning toilet bowl, so I will try again later. The older I get the more I enjoy mechanical stuff and hate electronics/computers/sensors.