• Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

'74 Cummins NH 230 TOP END ADJUSTMENT

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
555
Location
Etowah Tennessee
My old Dodge has this ol 230 in it and I was replacing the crossover tubes between the 1-2 heads and I want to adjust the valves and injectors but I don't know whether to use the inner base circle or the outer base circle method. Can someone lead me in the right direction,thanks
 

mekanik

Senior Member
Joined
Aug 20, 2015
Messages
944
Location
Canada's Northwest
Either method will work. The outer base circle method 75 in-lb on the injectors and intakes are .014" and exhaust .027"
Inner base circle method injectors are .170" dial indicator and intake valves are .011" and exhausts are .023"
 

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
555
Location
Etowah Tennessee
Either method will work. The outer base circle method 75 in-lb on the injectors and intakes are .014" and exhaust .027"
Inner base circle method injectors are .170" dial indicator and intake valves are .011" and exhausts are .023"
I'm a little ashamed to ask this,but how do I tell if I'm on the right stroke to adjust everything with the torque method?
 

mekanik

Senior Member
Joined
Aug 20, 2015
Messages
944
Location
Canada's Northwest
Roll the engine until the mark on the accessory drive lines up with the pointer on the cover.
The injector on the cylinder to be adjusted will be compressed and both valves should have lash.
 

DMiller

Senior Member
Joined
Feb 21, 2010
Messages
16,432
Location
Hermann, Missouri
Occupation
Cheap "old" Geezer
Alwasy start at B or 2-5VS as will run all the one end cylinders then swap to the other end of the boxes. Made it less confusing when showed others how to run a OH.
 

Truck Shop

Senior Member
Joined
Dec 7, 2015
Messages
16,556
Location
WWW.
Alwasy start at B or 2-5VS as will run all the one end cylinders then swap to the other end of the boxes. Made it less confusing when showed others how to run a OH.

That's a good way hands on but trying to explain on here is confusing. Better to just roll through starting
at #1-A and bar through firing order.
 

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
555
Location
Etowah Tennessee
That's a good way hands on but trying to explain on here is confusing. Better to just roll through starting
at #1-A and bar through firing order.
Here's where I'm at and I ask ya'll to excuse my ignorance, ok, I had the box off of 1-2 to change the crossover o-rings and I decided to run the OH and I can't figure out for sure which stroke I'm on. While I was at the A mark,the exhaust rocker on 6 was loose but not the intake,next I went to B and the 5 rockers would barely move and I wasn't sure so I rolled on to C and the 3 rockers I can wiggle a little and the 4 exhaust is loose,so I'm still scratching my head with a big question mark.
 

Truck Shop

Senior Member
Joined
Dec 7, 2015
Messages
16,556
Location
WWW.
It's alright---Bar engine back around to A and look for the loose exhaust rocker on #6 and tight intake.
Install the rocker box on the front two cylinders making sure push tubes are correct in cam followers
and rockers. Just torque to 15 ft lbs, check rockers on #1 cylinder-you will find both have clearance.
That will tell you that it's on the compression stroke. Finish by torqueing to 70 ft lbs.

On the compression stroke of #1 cylinder the rockers will have clearance and #6 cylinder one rocker will
be tight. On the compression stroke of #6 cylinder the rockers will have clearance and #1 cylinder one
rocker will be tight. Just the reverse.
 

Truck Shop

Senior Member
Joined
Dec 7, 2015
Messages
16,556
Location
WWW.
#1-A--VS--#1 cylinder valves closed rockers loose and #6 cylinder valve will be tight, adjust valves on #1
#5-B--VS--#5 cylinder valves closed rockers loose and #2 cylinder valve will be tight, adjust valves on #5
#3-C--VS--#3 cylinder valves closed rockers loose and #4 cylinder valve will be tight, adjust valves on #3
After #3-C/ the next stop is A again which is #6 cylinder which means you have bared the engine 360* from #1-A.
#6-A--VS--#6 cylinder valves closed rockers loose and #1 cylinder valve will be tight, adjust valves on #6
#2-B--VS--#2 cylinder valves closed rockers loose and #5 cylinder valve will be tight, adjust valves on #2
#4-C--VS--#4 cylinder valves closed rockers loose and #3 cylinder valve will be tight, adjust valves on #4

Injectors are adjusted at same time on each cylinder that valves are adjusted on.
 
Last edited:

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
555
Location
Etowah Tennessee
It's alright---Bar engine back around to A and look for the loose exhaust rocker on #6 and tight intake.
Install the rocker box on the front two cylinders making sure push tubes are correct in cam followers
and rockers. Just torque to 15 ft lbs, check rockers on #1 cylinder-you will find both have clearance.
That will tell you that it's on the compression stroke. Finish by torqueing to 70 ft lbs.

On the compression stroke of #1 cylinder the rockers will have clearance and #6 cylinder one rocker will
be tight. On the compression stroke of #6 cylinder the rockers will have clearance and #1 cylinder one
rocker will be tight. Just the reverse.
Thank you so much,I think I can get it now.
 

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
555
Location
Etowah Tennessee
#1-A--VS--#1 cylinder valves closed rockers loose and #6 cylinder valve will be tight, adjust valves on #1
#5-B--VS--#5 cylinder valves closed rockers loose and #2 cylinder valve will be tight, adjust valves on #5
#3-C--VS--#3 cylinder valves closed rockers loose and #4 cylinder valve will be tight, adjust valves on #3
After #3-C/ the next stop is A again which is #6 cylinder which means you have bared the engine 360* from #1-A.
#6-A--VS--#6 cylinder valves closed rockers loose and #1 cylinder valve will be tight, adjust valves on #6
#2-B--VS--#2 cylinder valves closed rockers loose and #5 cylinder valve will be tight, adjust valves on #2
#4-C--VS--#4 cylinder valves closed rockers loose and #3 cylinder valve will be tight, adjust valves on #4

Injectors are adjusted at same time on each cylinder that valves are adjusted on.
72 inch lbs, on the injectors,right?
 

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
555
Location
Etowah Tennessee
So,I havn't had this truck on the road since I ran the overhead but it was running fine while I moved it around the place here loading some logs on it,I probably ran it 30 minutes or so. Today I was about to haul a load to the yard and it started knocking first and then skipping,I don't know how to check which cylinder is missing on these engines,I've only done that on CATs and I don't know what to think if I set the injectors wrong,or got some trash or what, any advise is much appreciated.
 

charles walton

Senior Member
Joined
Nov 24, 2012
Messages
555
Location
Etowah Tennessee
Start cold, run your hand along exhaust manifold at each exhaust port, find the cold ones.
could raw fuel come out the manifold at the cylinder that's missing? It looked like there was a leak from 5 or 6 and I thought it might be the crossover so I pulled the dogbox and looked and it wasn't coming from there.
 
Top