Cummins NTC 400 Blue Smoke

the big cam 3 has the low flow cooling system with the 1.5" radiator hoses and dual thermostats . the big cam 2 has the high flow with the 2.5" hoses and single thermostat.
i'm not up on the BC 1 but I believe the tiing was different and there was different oil filter setups on each of them. the later ones having the bypass style dual filters. you usually see a single filter or a single with a luberfiner on the older ones

 

I have the PP parts in my '84 pete 359 with a ntc400 built to cpl 625. I run a 14613 trans and 3.55 gears with tall rubber. I have the teflon ceramic pistons, dual fuel line kit, mapwidth enhanced 4 series holset turbo,, ported exhaust manifold, +2 size injectors and reworked pump with PP springs and a zero button. PP supplied me with a cam key to set the timing at .080 and my buddy built it with all the parts. It loped heavily at an idle and smoked white smoke all of the time. I contemplated renting it out to parties for mosquito control but got red tagged by the environment dept. But it runs like a raped ape, about 36psi of boost and 270lb of fuel pressure. MPG's dropped to about a solid 4mpg.

I was told it should not smoke and that my rocker boxes were probably worn and possibly the valve bridges and injector links. So we replaced all of those. No change. The engine was all new with rebuilt heads with new valves, springs, etc and PP supplied all the rest of the rebuilt parts.

Been running it like that for over 2 years now and everytime I am in a truck stop someone is on the radio talking and complaining about the smoke.

So, finally I retimed it today. Added gasket to the followers and got it to about .073. White smoke at hot idle is finally all but gone and so is the lopey idle (well almost). A lot more responsive in the lower rpm range and my cruising fuel pressure and boost level have dropped so I can imagine that mpg will rise somewhat. Still runs great and the PP people have been very good at supplying parts to make it run with the best out there. I walk with 550 cats all the time and smoke about everything else. 425 and 475 cats suck my cummins fumes regularly. I highly recommend PP for your performance source.

 

Ivegotten the same problem with my 475' what's the differences between a Ntc 475 and a 400

 

Enjoyed reading this post so much,I just had to read it all over again....Did Pittsburgh Power recommend resetting your timing to 0.73 Dr.Hunt? You must have some grin across your face when you walk around those modern trucks with your '84 Pete 359

 

The smoke is normal due to fixed timing. As far as differences I am not sure besides being twin turbo and pump settings. Probably different pistons as well.

 

No, PP does not recommend that, they in fact claimed that I must have other problems. However I have a cam timing tool and the book on how-to. It was at .080, and now is at .073. Fuel pressure is at 270lb and boost peaks at 36psi, but most of the time I only push it to 33 at about 250lb fuel, which seems to be plenty.

If I had it to do all over again, I'd of got the high lift cam, followers and bigger injectors combined with the VVT unit. But when I called they had no VVT units in stock, and talked me out of going for more.

 

Sounds like your NTC is producing at least a healthy 600 plus bhp. How did the milage compare after you re-timed it to 0.73?

As you say...a high lift cam and VVT alone without touching the injectors would give you more power....no smoke,and a substantial milage improvment...

 

As I understood it the VVT would of just cleared up the smoke. Still would have had to remove the cam and press the gear off the old cam and on the new one. The new cam has more stroke on the injector lobe. That additional injector stroke combined with larger injectors would increase the fuel delivery to the cylinders. Having automatically retarded timing would allow more rail pressure by reducing the shock load on the injector pushrod, follower and cam.

The problem with mileage as I see it is that if the engine is turning the same revolutions per mile, injecting more fuel, it's going to get less mileage. Their argument is that you are less on the pedal to get the same boost, so mileage is the same in cruise. The advantage comes when pulling hills, less rev's per mile because with the higher hp you don't have to drop gears.

In my experience, that is not the case. With the .080 timing mileage went to heck, about 4 down from 6 prior to frying a piston when it was mildly upgraded. Interestingly enough at .080 timing the pyro would not go over 650.

When I tore it down after frying a piston, it had the offset keyway in the wrong way by previous owner, timing was at, get this.. .043, had the 4 series holset, unknown injectors, rail pressure was 170 psi gauge. It fried on a mild pull, grossing about 80K, turning about 1800 in direct, so was kind of weird, was only pulling 24 psi boost, but it makes sense knowing what I know now.

After changing the timing back to .073 fuel mileage went back up, cruise fuel pressure went down, boost went up and the pyro will not go over 750 deg. So, I am liking it alot right now! Getting almost 6mpg average. I know the theory behind the new electronic controlled models and it is superior. But you can't fix it on the side of the road and it is going to cost $$$$$$ compared to old school. So for me, it works, it may not be perfect, but it is mine, paid for and I like it. Now if I just had work, that would be a different story. So I said to heck with it and am now in law school, so when you guys need a hand, you will know who to call after December 2012.

 

I'm surprised they suggested .080 for an engine that was going to be ran on the road, what you reset the timing to is very close to the spec for a 400, and is good for the road.

I might have missed it, but what injectors are you running dr hunt.

BC3's were not low flow cooling, unless it was a crate motor built after '87, the 4's were the start of the low flow.

Dexterr, your 475 will have the MVT, a different cam, different 14:1 compression pistons, high flow injectors, and twin turbos. I think your smoke may be from a worn set of injectors, or it possibly could be that the MVT is not fully retarding the timing at an idle