If you're wanting to check "injector timing" , you'll have to locate and use one of the traditional dual dial indicator tools unique to Cummins PT fuel systems. Your manual will no doubt show you this, but one dial registers via a long stem through a removed injector hole the piston position relative to crankshaft rotation, while another registers the push rod travel. Different thicknesses of rocker box gaskets are available to move the low mounted rocker rollers in or out of contact with the cam lobe. One gasket choice has to provide a satisfactory average for two cylinders. If you disturb an old engine to change these, you must pull the housing end plugs to renew the "O" rings. Otherwise leakage is pretty much guaranteed once its all back together again.
If all you want to do is a valve, injector set, then just follow the instructions in your manual. In a nutshell that might be:
a)Remove valve covers and Jake housings(keep in order)
b)Clean gaskets, throw an overhaul kit into Jake housings if high
miles
c)Loosen all rockers, and remove the top rocker housings(for
replacement of rocker shaft "O" rings, same as lower housings.)
Reinstall, torque housings.
d)Follow the valve set info applicable to your engine, but yours
is probably A 1/6, B 2/5, C 3/4 as visible on the accessory
drive pulley. 11 and 23 thou was pretty standard for intake/ ex.
e)Injector values for top stops were something like 6 inch pounds,
but if you can rotate the small link which sits into the top
stop collar with your fingers, your close. The set point is part
of the above pulley points, and the chart will clarify that.
f)Torque Jake heads, you'll have to check adjustment value in your
book (I think it was 18 thou)
If you set your injectors too tight they can fail, too loose and the tips will carbon up.
Good luck,
Lorne

 

Lorne has it right on except the gaskets that change the timing are on your cam followers not the rocker boxes. If memory serves me correctly for every .007" of gasket it changes timing by .002". Used to have to do this all the time when changing the CPL of the engine during O/H. Don't see much of the big engines any more in our shop though. All class 6-7 engines now, hardly any class 8 come in.

 

[ QUOTE ]
Lorne has it right on except the gaskets that change the timing are on your cam followers not the rocker boxes. If memory serves me correctly for every .007" of gasket it changes timing by .002". Used to have to do this all the time when changing the CPL of the engine during O/H. Don't see much of the big engines any more in our shop though. All class 6-7 engines now, hardly any class 8 come in.

[/ QUOTE ]

every .007" changes pushrod travel .0015"-.002" i just happend to have have my notes right here!

 

i bought the tool a long time ago and dont use it much and need to go back to the book to to use it . seems like everything i work on now is a detroit . not that im complaining . but i do know its a pain in the butt to get em set right . and as far as the overhead , i seem to like to set the injectors with the torque wrench at 72 inch lbs on the firing order and recheck that inj two cycles later .

 

Setting the injectors at 72in lbs is using the OBC (outer base circle)method possibly a recipe for disaster. The OBC method as a rule is used on small cam inj, NTC/N14 engines with STC type injectors and N14 Celect. The other method is IBC (inner base circle) used with most L10 and NTC with top stop injectors. Using the wrong overhead set procedure will cause much grief. Post or PM your Engine Serial number if you are unclear on the method you should use or the differences between the setting procedure.

 

 

i have ran the injectors this way lots of times and like i said i recheck for zero lash two cycles away . what started me doing this in the first place was whin i came across one that the acc drive was not timed corectly . i dialed in the inj and found a starting place . when the drive was pulled at a later date and corrected i rechecked the inj settings to be correct . and yea i know about the stc setup as one time i had a confusing problem following up a repair that was done inhouse at a major leasing company (you gota love them school book mechenics that cant tie their own shoes but have the papers that say their trained and smarter than you are ) . but that was a long time ago .

 

Back along the way, we had a Pete conventional with the 475 twin turbo with MVT on the follower boxes (mechanical/ variable timing, also an 855 Cummins of course).
Ran pretty good (excluding the MVT rack always slopping about) lots of boost but not a great series match on the turbo's, no doubt poor maps put forward by an engineer between a rock and a hard place.
Regardless, following a major inframe by the local Cummins shop, it slipped out of wack and I lifted the covers, etc. to do my own set. I found a set of feeler gauges lodged in the valve train, not the reason for low power, but disappointing to find inside an engine.

 

I was unaware that series turbos had been used on anything factory until ACERT came along. What was the year of this, and what was its purpose?

Birken

 

Evidently so, the last guy I drove for had two Cummins and one Cat in Pete's. When I first went to work for him, he'd mentioned that he'd just previously removed the twins, and put a Holset back on and it pulled way better. We were getting ready to leave at the time so I could be wrong, but I think it was the Big Cam Cummins and not the Cat. All three were totally mechanical engines and he was head of "power trick of the month club", so for all I know the twins were not stock and just something he was trying out.

 

Hello! About '73 Cummins came up with the NTA engines. They were 370, 380, 400, and 420. With super slow timming and low compression, and a tappered nose crank, they set a new standard on smoke and broken crank shafts! The next step was the NTA FFC with two thermostats, straight nose crank and off set water pump. Still plenty of smoke but a little better durability. When the Big Cam came out around '78 the big power was the the NTC 475 with MVT and twin turbos. Cummins liked to call it "turbo compounding". The Big Cam 4 came out in the 80's, but it was '87 when the 475 was replaced with the 444. The next step was the NT-88 444xt.
If you want to see a real turbo set up, talk to your local old timmer at Cummins about the Hyper-Bar KV2300. It was an engine with compression so low that it had an extra turbo on it with a spark plug and a fuel injector, making it a jet engine, to pump air into the engine so it would run at low RPM at less than full power.

 

[ QUOTE ]
Back along the way, we had a Pete conventional with the 475 twin turbo with MVT on the follower boxes (mechanical/ variable timing, also an 855 Cummins of course).
Ran pretty good (excluding the MVT rack always slopping about) lots of boost but not a great series match on the turbo's, no doubt poor maps put forward by an engineer between a rock and a hard place.
Regardless, following a major inframe by the local Cummins shop, it slipped out of wack and I lifted the covers, etc. to do my own set. I found a set of feeler gauges lodged in the valve train, not the reason for low power, but disappointing to find inside an engine.

[/ QUOTE ] Went to do Main and Rod bearings on a 550 Cat the other week.Another guy was pulling the Pan down and Found a 12" long punch in the Pan sump! /ubbthreads/images/graemlins/eek.gif /ubbthreads/images/graemlins/grin.gif.The owner said he Knew Nothing about how it could have gotten down in there /ubbthreads/images/graemlins/rolleyes.gif

 

I've been known over the years to drop a couple of jake box hold down nuts down on the cam followers but no tools yet. /ubbthreads/images/graemlins/biggrin.gif

I ran a small cam NTC 335 for 27 years in the same truck. It was updated to a NTA 420 and I timed it back to 43 with a Switzer turbo 4LF and later to a 4LH. Had the block out once for counter bore rings and .003 redeck was all we did other than in frame kits. Still has original standard crank. Over the years I went through a couple of cams and a front housing cover. The harmonic balancer was changed a few times also which was necessary to keep the crank from breaking.

It's still running but I don't use it much now as that old Pete is hard on my body.. /ubbthreads/images/graemlins/grin.gif

 

I just bought A 87 eagle w a ntc 400 in it I neade to run the overhead my data plate says intake t.s.zero inch lash

 

use the

abc method..injectiors set 5inlbs preload...in .011..ex .023,,,turn to "A" set valve on #5 and inj on #3.."B" set val on #3 and in on #6 "c" set vl on #6 and IN on #2 and so on in firing rotation 1 5 3 6 2 4

 

adv. or retard ?

 

The injectors are adjusted via the firing order 1-5-3-6-2-4 and should be set along with the same valves at 6-inch lbs or finger tight. So if your timing mark is on A which is 1 or 6 find the valves that are loose that is the cylinder you will adjust the valves and injector. The other cylinder will have an exhaust vale in the down location.

 

has anyone tried putting heads from a big cam on a small cam did they use the same heads in those models?

 

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