So I have a 400 big cam, starts in the cold like a 400, smokes like a locamotive if cold, wicked touchy mid throttle, truck jerks bad at times mid throttle, you have to drive full throttle or no throttle to drive smoothly, loaded it's a little better. If I plug the truck in at night I can prevent the cold smoke, and pulls hard loaded, and the jake could hold back a locamotive. So here's the question, if I send the injection pump out, it may help the jerky throttle, but truck will still smoke cold. Option 2- pull the engine buy an N14, throw enough money at it and I can have 550 smoke free hp. Takes a lot of cheddar to make this option happen. Option 3- buy a junk N14 with a bad crank or block, swap the parts, using my block, crank, rods, swap Pistons, and fuel system parts, cam. But is crank and block the same? Less cheddar more sweat equity. Thoughts?
What CPL is your current motor? Cummins used a couple different ways to manage the timing. I've driven a few that acted like yours does and with some tinkering those issues were addressed. How much of the history do you know? Last time overhead was run? Mileage on motor itself, injectors etc?
I have owned one that runs exactly like you describe for 26 years. Over the years I have replaced heads, injectors, fuel pump. ran the rack occasionally. nothing ever changed the way it ran. or smoked after a cold start. I never understood why it smoked raw fuel so bad if it was under 45-50 degrees. it always started quick and pulled very good. I never had any sparrows living in the building I kept it in. LOL I did get the throttle a bit better by reworking the linkage so it had a longer throw on the pump. witch slowed down the movement. (old dirt track trick) Made it less jumpy.
Does this engine have oil pressure operated step timing control? If so the STC tubes may have blown out of the injector adaptors, once they get sprung out of place they leak off the STC signal and lose the injector timing advance at idle. The result is lots of eye burning white smoke and a drastic drop in hot oil pressure at idle.
The later BCIII 400's did the smoke thing brand new. I was told if was a compromise for what they called emissions back then. It is related to camshaft timing and probably why the STC system evolved. That is just the nature of the beast. As far as the surging at mid throttle it sounds to me like a governor issue. Replacing a solid rod with a cable to the pedal was great in some trucks. However surging from that is expected more at slower speeds. The last one of those running where I worked was heavy haul and a bit hot. If it was started up, winter time cold, in the shop we feared someone would call the fire department. It would roll two feet of coal out the top of all the doors. After warmed up it cleared up and had perfect manners.
What position is the throttle lever on the pump? It can't be forward of the break over point or past 90* or it will cause a very touchy throttle. And what series is the engine II, III, IV, NBCIV or NT 88. The NBCIV, is STC injector and those do not set to original factory Specs. As far as smoke part of that is compression ration on big cams Although the first BCIV was higher compression than any in that series and would be a BCIV CPL of 676 mainly. Check the throttle shaft for up and down play, When was the last time that pump had any attention? Is that pump still sealed? Here is a link to procedure for setting STC injectors if it has them. http://www.chathamfuel.com/generic....Tech Tips - NT/N14 OBC Overhead Set Procedure Truck Shop
You can make that Big Cam run. I had a BCIII CPL 625 that I installed double ni resist pistons/liners and heads from CPL 676. Had custom built 8 orifice injectors with a KTA 525 1 inch gear pump and fed fuel in both ends. I used the cam from CPL 676 because it has slightly more lift. Pulse manifold with a HT3B turbo. Timed the injectors at 74-little less throttle response but more hang time between shifts. The pump was re-calibrated to match the rest of the components. It would run. But the secret is in the injectors if they don't have the flow you don't have the power plus it will cause higher rail pressure. IMO. Truck Shop
Great responses, I bought the truck last spring, it is an 81 western star. I converted the front axle from wedge to s-cam brakes and hub pilot aluminum wheels. Rebuilt the power steering gear, and removed 10miles of homeowner wiring. I replaced the ball studs on the linkage hoping to help the issue. Pretty sure it is a big cam 3, and don't think it is an stc engine, thought they came out later, considered pulling parts from an stc 444, to help the smoking cold. I will have to look tomorrow for the CPL. The injection pump shop I use think there may be a governor issue causing the jerkiness, he said he has been fighting with smokey 400's his entire career and suggested also running the overhead, but nature of the beast. I read about 20 pages from Pittsburg power on building horsepower in a big cam, but when I called them I felt like I was bothering them. Truck is pretty cool short cab long hood and a big cam 3.
81 should be a BC I or BC II. They had an aluminum oil pan and single spin on filter. All of the ones were I worked had a LF750 by-pass filter also. Big Cam III has twin spin on filters and a stamped steel pan. Keep those STC parts away from it. Cam changes and such make it non compatible. Some people put Cat charge air coolers and radiators in front of them. If you do anything much to it it needs a pyrometer. An N14 would need one of those also.
Sounds like 449 CPL . They would white smoke when cold . Slow time setup on the cam timing . Start pretty decent & made good power , just smoke up the valley until it warms up . Have one in a dozer .
Yes the original engine was a 300 with a 9 speed, at some point the 300 was pulled and a 400 installed with a 15 speed, the oil pan is a stamped pan, so big cam 3, i made sure when i bought the truck it had large radiator hoses and wasnt low flow. The snow on the hood is almost level with the top of the cab, walking on the snow i look directly into the windows yesterday. I will work on getting the hood open this afternoon and get the CPL. I plug the truck in because i am afraid the fire department will show up cause they think my barn is on fire, and yes light grey smoke, lots of it, looks like a brush fire with a balsam tree on it.
We considered that no smoke after the 25 head herd of 8V-71's left each morning.
Given all the horse power and torque ranges in Cummins Big Cam engines here are the number of CPL's for each series BCI---26 different CPL numbers from 205 to 661 BCII---33 different CPL numbers from 329 to 543 BCIII---37 different CPL numbers from 530 to 1411 BCIV---35 different CPL numbers from 642 to 1352 And every one is a smoker. Truck Shop
I wish you'd have sent that herd my way! I don't know what it is about those old Detroits but I sure do like them.
The reason it smokes has everything to do with the timing and fuel rate of the injectors. All pt pumped engines were fixed time and smoked white at cold start and after cyl temps come down at long idle times. That is the way they are. Sick of it? Go STC. Sending you injectors in to get cleaned and reflowed to stock might help. No fancy tools to work on a cummins, just a butter knife and pliers. If your handy a good fuel shop could go through your pump and injectors for a grand if you pull em.
400's of ANY CPL were smokers, decompressed where the pistons have no valve reliefs as they do not get that far up, took boost to get the fuel to burn. I missed out on the STC engines(luckily) heard they were very much the way described much like a two stroke with an expansion chamber either on the pipe or off and harsh getting there either way.
Put a N14 turbo on a 855 and now you have a electric motor.
I guess the big question is what are your plans for this truck? Remember N14's take a air charge cooler. Cheaper to repair the engine you have and more practical. The BCIII was the best of the big cams, the IV, NBIV, NT88 and 444 were all problem childs that damn near sent Cummins to the brink. Those were all experiments that didn't work very well. And really what saved them was the N14 electronic. Truck Shop
MVT on the 444 was a joke, STC on the others had its issues, but did ok when it was working and did reduce idle smoke quite well, as I recall even the N-14 mechanical used STC.
Worked on many 531's it was a good BCIII 400. personally I would give it a tuneup and replace injectors and see how it runs. Check the push rods for oil inside while your there. It won't stop it from smoking cold but it might clear it up some. If you have injectors puddling fuel that doesn't help. Truck Shop
Yes the N14 mechanical used STC injectors. Once you threw the original injector locking tool and manual away and torqued them to 125 inch lbs pre-load they ran great. But the original settings only removed a slight amount of slack and caused the injector plunger to wear fairly fast. The 444 and mechanical N14 runs way smoother set with pre-load on the injectors, plus injector life goes up drastically. Truck Shop
Gonna try that on the next one I see. I've always used the STC tool, but set them very FIRMLY at zero lash. that stupid 5 lb inch tee handle has no feel whatsoever. Another one of those things Carl P showed me years ago.
4/83 build code, that was during my days and will be a old standard 855 NTC400 that will smoke a light hazy blue especially when cold. Trying to see what that greasy line is running behind the throttle arm on the pump, it is in contact? Second if you have someone in the cab slowly step down on the throttle while watch travel is it smooth and not spot sticky? Should be Nothing in contact with the throttle rods. Then one final is the break over throttle arm loose to where it can break over early in travel and not open for throttle?
Originally i replaced the throttle linkage, and did some checks on the break over arm. I got bit pretty hard by a big cam once years ago that had the same jerky symptoms, i changed the injection pump on, and it wasn't the problem, ended up being the throttle linkage. I know some of the N14 parts are interchangable, however i dont know what, and if its worth the effort. If i am going to get a thousand dollars into building the pump and injectors that i have is it worth buying junk yard engine, and swapping N14 parts into either electric or mechanical. I bought the truck because i was looking for a classic truck, that i could haul my excavator around on a tag trailer and haul some dirt. I wanted a 350 peterbilt, I Originally am from Port Angeles Wa, in the late 70's, early 80's and have a soft spot for a late 60's pete logger. On the east coast this is a rare truck, and the few that are here, they want alot of money for. So when i came across this 81 Western Star, with a galvanized cab, and a Big Cam 3 i was all in, the cab is short like an early pete, not sure when the cab got taller but a heritage cab is taller than My 4964, and a long tall hood, very similar to an Autocar AF64. It is what i would call a working hobby truck, as most of my work is mechanic work. Not making it parade ready, but reliable cool old truck, if i make a couple bucks with it great.
Any pics of the truck?
Just stick with what you have, IMO. The BCIII is a good engine for what your doing-for years those engines have moved allot of equipment, freight, logs and dirt. Is the block dry around the head gaskets? If it is there's probably not much to worry about at this point. Do the normal things to check it over. Check the turbo for excessive radial play and pushing oil past the seals. Run the overheads and install some fresh injectors. Drop the pan and roll a set of rod and main bearings in it. Run it and see how it is, if need be have the pump gone through-lord knows how many knot heads have fiddled with the button. If its stock it should have a #27 button. Interior parts for those Stars are hard to get by the way. Even when they were new you ordered and waited a month. Those old Stars were good looking rigs. And the cab was built in Kelowna BC. Autocar, White and Diamond T to name a few used that cab. Truck Shop
Ok so here are some pics
Not a bad looking old girl. Truck Shop
Galvanized cab, what do you get a guy for Christmas? a glitter ball shifter of course. I would like to redo the origional seats.
Would like to find a logger bumper, which takes a different front frame crossmember, and a better grille.
So the throttle issue was caused by a cab mount bolt that was loose on the passenger side, looked fine from engine compartment but when pulled the rubber floor matt back, the washer had worn into the floor causing the throttle jerkiness when hitting any bump.
https://bend.craigslist.org/hvo/d/bend-white-western-star/7271600260.html
Big Red has fifteen speeds and six in the hole. That old Star is ready to pull! That Cummins Eight-five-five makes all kinds of boost. Fire it up, smoke the pigeons from their roost! Big Red has no black box and no ECM. Just twelve button that pump, and point her in the wind!
And wait for the cam to go south.
Lol. That 855 Big Cam marketing ploy was funny at the time. I appreciate the 855 for what it was. They kept us busy changing head gaskets and rolling bearings, but they hauled the mail and got the logs out of the woods. I was never a Cummins Guy. Not that I didn’t like them. There was a lot of good Cummins guys. So, I tended to get the Cat and Detroit work. So, I never got into them. I like to hear a well-tuned Big Cam III with all the updates and tweaks pulling a load of wood.
This is a working restoration, hoping to replace the injectors this spring and get a little boost in horsepower. When I bought the truck the old owner turned a few screws on the pump and she pulled pretty hard, I sent the pump to a local pump shop and it would fall flat on its face in a hill, found an air leak in the return line to the tank and it got better, probably back to stock numbers, not the power I had when I bought it but usable. I know there is some power in there and hoping a fuel shop in maine will put together injectors and a pump that will pull.
The change to lower oil pressure starting with BCII engines was to make the main/rod bearings last longer which it did. The problem with high rail pressure was what it does to injector lobe. The way to achieve more fuel is use the 9 or 10 orifice injectors to relieve the rail pressure. A KT pump with a 1" gear can be used on a 855 after being calibrated {standard gear was 3/4" . Stock rail was 165 on average for most big cams and some only 158, But I have seen where #42 buttons were stock and #5 installed. That shoots the rail over 250 easily and good by injector lobe. My BCIII only ran 200 on rail with 10 orifice injectors and a KT pump with a HT3B turbo for a 525 N14, at 14-1 compression it ran a steady 36 lbs boost on a hard pull, but I didn't run it that way.
That’s a recipe for success from the church of the Western Star! I’m taking notes.
IIRC the stock injector was 8 orifice with .007 orifice, the 10 orifice was .0085 and IIRC the plunger and barrels were direct feed/high flow.
88nt bc 4 at 350 now will it come up to 400 or better with out major changes ?
Piston change most likely but to be sure need CPL #. Most 400's are 14:1 compression ratio and 350's 14.5:1 plus.---The 300,315 engines were 17:1. But the NT88 engines were b*****d, different oil oil cooler and bolt pattern in block, water pump is different plus bolt pattern. There are several things that are not compatible between a regular BC 855 block and the NT88.
Hey fellows not to get into anyone’s business…you do NOT need rail pressure over 195 pounds. The way to set your engine is to have the pump set with the stiff torque spring (red stripe) and go lower on the button size for fuel pressure but not over 195 pounds of rail pressure. Have the injectors flow rated so they can handle the new amount of fuel you are sending them now. If you do not have them flowed rated you place too much pressure on the cam and wear the lobes on the cam because injectors can’t handle the amount of flow. These Cummins injectors push fuel by the cam lobe moving injectors up and down Set your 400 big cam III at 20 % above specs and match injectors to pump you will not hurt the engine and she will tote the mail. One last thing set aneroid valve enough to give it better throttle response….but not so much she smokes bad. You just a little dark lingering puff when changing gears. Then get in her and start “stepping”
My buddy Rog has a shop on the edge of town. He says there’s just one thing about a fo-foty-fo. They run like a scalded dog until the top end goes. Then he said to me, Coaldust, we can turn your beast into a Big Cam Three. Then, Ol’e Rog put a twelve button in my pump, and now I can make the front wheels jump. Knowwhatimsayin?
How old are you? A good way not to look like an *** on the first few posts is to enter mild, quiet, peaceful & content. Not telling everyone how to jack the fuel on a BC. But then again might be AI.