From: Dave Barbieri (Dave.Barbieri@marshall.tstc.edu)
Date: Fri Jun 04 2004 - 15:00:20 PDT
Hi Adam -
Not sure about the 'first 855's'. I've seen several old N-series
engines. One was in a 1968 Western oil field winch truck. It was an NH
220 normally aspirated and it was mounted leaning towards the passenger
side of the truck, sorta like a Dodge slant six. Wild looking
installation! No cooling jets. We have a 1971 NH 220 that was donated
to the program. It also has no cooling jets. Similar in appearance to
the NHC's that the 5T trucks run, but when you get up close, there are
some definite differences. The heads are not set up for fuel delivery;
all fuel plumbing is external. The injectors are large, bulky things
that bolt into the top of the head kinda like the later model
injectors. Two engine teams are working on this puppy; when we get it
running, we're gonna add it to our 'museum'. <G>
As far as smoke goes: yes, NA's smoke a LOT more than turbo'd motors
do, especially under load/acceleration. We use NHC 250's in the engine
labs. They generate a lot of smoke on startup and when we throttle up.
HOWEVER, running a high idle (2100 rpm) the smoke thins out and goes
away, since the governor only lets the pump supply enough fuel to
maintain rpm. Three things to check:
1. Valve adjustment
2. Injector adjustment
3. Injector timing
I listed the valve and injector checks first, since they're fairly
straightforward and easy to perform with basic tools (feeler gages,
screwdriver, ratchet/socket, combination wrench). Also, this is
usually the culprit for excess smoke and crummy performance. Checking
the injector timing is a bit more involved and takes, at the very least,
two dial test indicators with magnetic bases.
If you decide to try installing a turbo, let me know how it works. We
have all the pieces/parts to install a Holsett unit on one of our
NHC's. Sorta like a Clean Air Kit for the Cummins. <G> If we decide
to do it, we'll keep the size pretty small, since the object is to turn
smoke into horsepower. We're not going to play with injector nozzle
size or lift; don't want to overtemp/overstress pistons.
Dave Barbieri
>>> "Adam Suess" <ajsuess@hotmail.com> 6/2/2004 10:39:35 PM >>>
Dave and list,
I was told by several mechanics that the first 855 Cummins did not have
oil
cooled pistons turbo or not. Is that true? We have 2 turbo versions but
both
newer 1979 and a 1990 with oil jets. Another question I have is I
picked up
a xm 813 for the fire dept last year and it smokes black at 2,100 rpm
no
load it does smoke more under load but not much. It also seems very
sluggish
for 250hp. At first I thought it was a plugged air filter or
restriction
some where but that was not the case. It starts good, uses no oil and
runs
good other wise. Just that it smokes black with no load. Is that normal
for
a Nat asp 250? Or do I have problems like timing? Our turbo 855's don't
smoke at 350hp in a ford 9000 tractor and 375 hp in a Case IH tractor .
We
were and still are considering adding the turbo off a salvage engine to
the
XM 813 for the number of hrs we use it I don't think we would melt it
down.
Thanks, Adam Suess
This archive was generated by hypermail 2.1.4 : Sat May 07 2005 - 20:33:22 PDT