General Discussion     Tech Questions     Parts & Services     Suggestions/Ideas     Help & Website Instructions     Blogs    

Truck & Transportation History

Home Search Tags


Big Cam 4 cpl833

Posted By wolfegrading Wednesday, February 02, 2022 11:10 PM
Add to Favorites2
Author Message
wolfegrading
 Posted Wednesday, February 02, 2022 11:10 PM
.

. - (149 reputation). - (149 reputation). - (149 reputation). - (149 reputation). - (149 reputation). - (149 reputation). - (149 reputation). - (149 reputation). - (149 reputation)

Group: Forum User
Last Active: Monday, March 28, 2022 11:20 PM
Posts: 6, Visits: 32
149
Looking to buy this to replace ntc 350 small cam in my 1975 Pete .SN-11426839-cpl-833-dom-9/87- Oil is coming out between exhaust manifold and head when first cranked also slow throttle. Cummins says its a N14 instead of big cam 4.Was getting ready to overhaul my small cam again then some offered to sale me this I really wanted a Big Cam 3. Any help would be good.I would won't to convert this engine to high flow.
Wednesday, February 02, 2022 11:38 PM by wolfegrading
Geoff Weeks
 Posted Thursday, February 03, 2022 2:53 AM
ATHS Member

ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)

Group: Forum User
Last Active: Sunday, June 12, 2022 9:31 AM
Posts: 3,778, Visits: 17,340
I can't look up the serial number But the CPL makes it a 365/400 hp Big cam 4
There is a lot to change to make it high flow, If you don't have all the parts and have to search yards to buy the pieces, you'd be better off haveing a low flow radiator made for you '75 then stitching together pieces. I find the low flow gives better mileage as well. The big cam 4 has lower press fit liners which are a big improvement over the upper press fit design used in previous big and small cams

Just going off memory:
Thermostat housing
water pump
after cooler
aftercooler pipeing to rear of the block including the "plug" in the rear
cross over from turbo to aftercooler
pipe from oil cooler to thermostat housing
pipe from thermostat hosuing to water pump
misc clips, brackets and retainers to secure the piping in place (little 1/2 moon retainers hold the piping in the castings
The job is ok if you have a big cam 3 and the 833 sitting next to each other and can swap parts, it would be a pain to try and locate everything piecemeal and then find you are still short some parts.
Easy choice for me, change the radiator or change a lot of little parts. one thing or many. I'd go for the one and get better milage to boot.
Geoff Weeks
 Posted Thursday, February 03, 2022 3:08 AM
ATHS Member

ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)

Group: Forum User
Last Active: Sunday, June 12, 2022 9:31 AM
Posts: 3,778, Visits: 17,340
Also forgot to say you need to pull the upper water rail and replace the restricter washers with the square cut O rings in the woter outlets of the heads,
I think, but am not sure the radiator pipeing will work from a small cam to a big cam high flow but not sure.
Oil leak, not clear if that is on your present engine or the one you are thinking of buying. If it is on the 833 and only is there at low throttle setting is could be a leak in the plumbing for the STC system on the injectors, Can't say more without looking at it.
Newto
 Posted Thursday, February 03, 2022 9:47 AM
.

. - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation)

Group: Forum User
Last Active: Yesterday @ 9:54 PM
Posts: 149, Visits: 2,720
Because its an STC engine there's no easy fix to change it to high flow cooling.

The rocker boxes are slightly wider on STC than on BC3 to allow for the oil supply manifold to the injectors.This necessitated the changing of the water manifold on top of the heads to give them clearance.So you can't use BC1,2,3 water manifolds on the centre or rear head....but.....you need to use a high flow thermostat housing on the front head to get the water to the radiator but the jumper tubes between water rails are different diameters.

We modified a lot of engines back in the day by converting back to top stop style injectors and BC3 water manifolds, rocker boxes and camshafts.

You can still use the low flow aftercooler by running an external water pipe from the back of the block just below head height to the front of the aftercooler. That lets you still use the round the front air intake manifold.

Big project......I'd either leave it at low flow and get a rad to suit.....orrrrr......keep looking for a genuine BC3 engine.

Newto
Thursday, February 03, 2022 10:24 AM by Newto
Newto
 Posted Thursday, February 03, 2022 10:23 AM
.

. - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation)

Group: Forum User
Last Active: Yesterday @ 9:54 PM
Posts: 149, Visits: 2,720
http://forums.aths.org/Uploads/Images/49005d96-b23c-45d0-8cd1-0ca.jpeg
Geoff Weeks
 Posted Thursday, February 03, 2022 10:34 AM
ATHS Member

ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)

Group: Forum User
Last Active: Sunday, June 12, 2022 9:31 AM
Posts: 3,778, Visits: 17,340
Newt,
I've only been around 2 or so 833's, They were 1/2 way between the Big Cam 4 fixed time and the NT88. I think they were the one refered to as the "New big Cam 4" Both of the 833's I've been around had the older style upper waterrail like the 676 and of course the STC plumbing in the rocker box.
The STC rockerbox on the NT88 precludes using the two bolt (old style) upper waterrail so I am not sure how they did it on the 833? I know it also had the old style oil cooler (cast aluminum with core vs the sealed steel one for the NT88's
I know one person who used an early small cam thermostat housing that was smaller than the one used on Big cams.
There are a few ways to do it, but all in all, I'd keep it low flow.
So I guess I am asking, did the 833 use the same rocker box as the 840 and other NT88's or was it unique to the "New Big Cam 4"?
Newto
 Posted Thursday, February 03, 2022 1:53 PM
.

. - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation)

Group: Forum User
Last Active: Yesterday @ 9:54 PM
Posts: 149, Visits: 2,720
Hmmmmmm Geoff......

Bloody good question........

We didn't have the 833 cpl's down here....or the 88NT's.....we skipped straight from the updated BC3 with Holset turbo's etc (cpl745) (known here as an 86NT) to what they originally marketed here as an N14 but later changed back to calling a BC4 with STC.....CPL's were 903 and 904......N14's here then became the Electronic engines.

All rather confusing......but I do remember that your 88NT's had a higher lift cam and longer pushrods that meant the rocker boxes on those were unique.....I'll go dig out some of my archives and see what I can find.

Cheers,

Newto
Geoff Weeks
 Posted Thursday, February 03, 2022 2:13 PM
ATHS Member

ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)

Group: Forum User
Last Active: Sunday, June 12, 2022 9:31 AM
Posts: 3,778, Visits: 17,340
I have heard, but not checked myself that the NT88's like CPL840 and their STC brothers) used a different rocker arm ratio than the early rocker boxes. I know on the early ones you can get all the headbolts out of one head with the adjacent heads rocker box in place, but not with the NT88, you've got to pull at least two if not all the rocker boxes to pull one head.
I am sure the NT 88 push rods are the same as the other Big cams.
The 833 was an odd duck for sure. I owned a 676 Big Cam 4, and a NT88 840 so have been up to my elbows in both. The places I have worked each had one 833 each, and had little problems with them, but they seamed a 1.2 way stage between the early (676) and the late (1211) NT88's
I lost my login to Cummins to look up the parts list.
Newto
 Posted Thursday, February 03, 2022 4:07 PM
.

. - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation). - (33,901 reputation)

Group: Forum User
Last Active: Yesterday @ 9:54 PM
Posts: 149, Visits: 2,720
Geoff...

Service Parts Topic 87T0-3 Introduction of the 88 Big Cam IV Engine lists the design changes on the 88NT over the previous New Big Cam IV (NBCIV).
I'll summarise as best I can......

Same cylinder head casting but valve seat inserts .070 thinner to allow less valve protrusion into the cylinder and no longer protect the injector tip.

Different valve spring retainer to provide additional clearance for the rocker levers.

Compression ratio's increased on all models...300,315,350 to 16.7:1...365 & 400 to 15.5:1....444 to 15.0:1......all new piston design with shallower valve pockets, new bowl design, dual ni inserts.

Entire overhead strengthened to increase injection pressures from 12,000psi to 18,000psi and injectors have smaller drain orifices to reduce amount of fuel returned to tank...RDF Injectors.

New injector links needed due to new rocker shaft location and increased height of the new style rocker box which also requires removal of 2 boxes to remove 1 head due to obstructing head bolts.

Rocker Shaft diameter increased from 1.1235" to 1.3725" for more strength.

New stronger Rocker levers and ratio changed from 1.76:1 for all levers to 1.4:1 for Valve Levers and 1.5:1 for Injector Levers.

Pushrods lengthened to work with the new overhead geometry.Injector Pushrods are 0.311" longer & Valve Pushrods are 0.297" longer.

New Fixed time and STC Camshafts with higher lifts and increased Injector Plunger travel from 0.294 to 0.318"

New C Brakes....of course..

New Water Pumps and Accessory drive pulleys

New style single pass "tank type" oil cooler

Thats it .....few more minor things but that will do.

Sorry for the length of this post....and slightly off topic as well.

Newto
Geoff Weeks
 Posted Friday, February 04, 2022 1:26 AM
ATHS Member

ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)ATHS Member - (577,987 reputation)

Group: Forum User
Last Active: Sunday, June 12, 2022 9:31 AM
Posts: 3,778, Visits: 17,340
Ahh, the rocker lever ratio did change! The push rod also, good to know. I am still in the dark as the 833 is list as a "New Big Cam 4" in my CPL book, which begs the question about the rocker box? the 833 had STC injectors so must have the oil plumbing external to operate them, but from what you posted and I observed, they used the earlier rocker box geometry. There must be a "New Big Cam 4" only rocker box for them.
The 833's I been around used the "all in one" full flow/bypass oil filter on a single pass oil cooler that still used the replaceable core and cast aluminum housing, something else I have seen nowhere else.
The New Big Cam 4 was only built for about a year from what I can see, IIRC my 676 had a '86 build date and my 840 an '88 build date. Explains why I haven't seen many.
Original poster hasn't been back, so I don't think we are doing any damage being "off topic".

Similar Topics

Expand / Collapse

Reading This Topic

Expand / Collapse

Back To Top