My '89 9670 build


For you lovers of the Class 8's and bigger.

Golden Jubilee
Golden Jubilee

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Post Thu Oct 19, 2017 2:17 am

Re: My '89 9670 build

Do you like the PT Cummins system?
I would rather have tools I do not need than to need tools I do not have

Golden Jubilee
Golden Jubilee

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Location: Lyman, IA

Post Thu Oct 19, 2017 7:55 am

Re: My '89 9670 build

nikkinutshop wrote:Do you like the PT Cummins system?

The only thing simpler is the unit injector Detroit used. The PT is reliable and easy to work on. The Bosch type injection pump that Cat uses has much more control of the timing as engine speed increases.
Each has its advantage and drawback. I think the PT is a good middle ground between Detroit and Bosch/Cat type.
On a Detroit, there are a lot of mechanical adjustment to make the whole engine work as one unit, no cyl working harder or less hard than the rest. On the PT system the injectors are flowed and set on a test stand and should hold that adjustment though out the injectors life. The only adjustment on the engine is the rocker lash.
The Bosch system is very complex but very reliable, the problem comes after a million or two miles it is very expensive to overhaul.
I've found this helpful
https://www.youtube.com/watch?v=KzuwdxEJfQA

Golden Jubilee
Golden Jubilee

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Joined: Thu Dec 27, 2012 12:45 pm

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Post Fri Oct 20, 2017 6:00 pm

Re: My '89 9670 build

I have had experience with Detroit Unit injectors and even some time rebuilding the older DD mechanical governor systems. I was present for one rebuild on a Cummins PT and I was the guy handing the tools to the real mechanic who did the work. One of the sound good engines was the Cummins 903 V8. the company had about a dozen of these monsters. I remember the 903 having problems but I don't remember very much about that, either. I have been retired for nearly 14 years.
I would rather have tools I do not need than to need tools I do not have

Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

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Post Fri Oct 20, 2017 6:11 pm

Re: My '89 9670 build

The Nine o nothing had a much better rep down under and marine than it did in N/A trucks. I am in inline guy and never liked V engines of any kind.
The Detroit injectors are very simple and goes a long way to explain why the 2 strokes had such a good reputation. As long as you have rail-pressure at least some of the cyl will fire, regardless of the rest. The engine may not run on all 6,8, 12 etc, but will get you home.
The PT system is a little more complex, and inter-dependent, but still is simple enough for someone like me to work on in my yard.

Golden Jubilee
Golden Jubilee

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Joined: Thu Dec 27, 2012 12:45 pm

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Post Fri Oct 20, 2017 7:21 pm

Re: My '89 9670 build

The introduction of DDEC to GM Diesels made a big difference in performance and improved economy. Diagnostics was better, but, that sneaky DDEC like to cover for a failing cylinder and sometime it was difficult to tell there was a problem with the old hands-on diagnostics. That is, unless a person noticed that the header was cooler on one cylinder. I bought a RAYTECH laser temperature gun. A quick exhaust manifold scan, at the ports, could often direct any more diagnostics. I like the RAYTECH for air conditioning diagnostics. Now, my wife uses the Raytech to check the roasted turkey and the temperature of the jam she is making.
I just checked my self to see if there is any life left and I am at 97F or 36.5C. I AM ALIVE! I AM ALIVE!
I would rather have tools I do not need than to need tools I do not have

Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Tue Nov 28, 2017 10:24 am

Re: My '89 9670 build

Got the last two spoke hubs rebuilt and on. For some unknown reason they torched the drums bolts off and none of the hubs had axles studs. Lots of time spent with a tap and die and double nutting everything, I was able to pull 10 studs and get them in the hubs. A little blue locktite and they should be good. Why not red you ask (bearing and stud mount locktite)? The threads on the studs are already a tighter fit then std bolts, and the studs are hard, so if one breaks I want a chance of getting it out. I'll take the off chance that I'll back a stud out when I next pull the axle.
On another topic, I have a plan to get the Marmon done also. Several years ago I bought a very good looking Hendrickson beam on leaf "cut-off". It looks almost brand new but has suffered a little being knocked around in the junk-yard. Two of the S cam brackets got a little bent, but nothing a press can't fix.
The problem with the Walking Beam suspension and also one of its strengths, is there is very little "adjustment" that can be made once it is installed. This means anyone doing the frame splice must get it dead-on from the get go. It makes me nervous farming the job out, but there is one guy on JOT who has a good rep, and may do it. He is in Tx about 800 miles from me, so that was one problem we have to over come, another option is a shop closer but if they do it wrong the truck isn't worth much.
The '89 cabover has a lot of small things that need correction, small but not nesserarly cheap. It also needs a set of tires and that is never cheap. I don't know when I'll plate it, I will keep picking away at the small stuff as I have time and money. At least today, if the little bunk had a catastrophic failure, I could put it on the road with a weeks down time, It wouldn't be done, the A/C system needs to be rebuilt, and there are plenty of other little things to work on, but it would get me back makeing money, something it couldn't do for the past 10 years.

Golden Jubilee
Golden Jubilee

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Post Wed Apr 18, 2018 2:34 pm

Re: My '89 9670 build

Picking away at the little things when I get time. Working for a living really get in the way of the stuff I want to get done.
I picked up a set of Deep Cycle batteries and made a set of battery cables for it. I used lugs for off grid battery systems, the good thing is there not likely to break or corrode, but the bad thing is you can't stack them on a stud.
The positive used 3/8" studs and the negative use 5/16" and the terminals reflect this. I didn't include the ground cable in the splice, like I did with the hot feed, so if there is a need to quickly dis connect the batteries from the truck, it can be done at one terminal.
Attachments
89 battery 3.jpg
89 batttery 2.jpg
'89 battery 1.jpg

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Post Thu Apr 19, 2018 9:19 am

Re: My '89 9670 build

6 Volt in series? Looks good the way you have them, Kept all your runs the same length it looks like, they should charge fairly equal. I want to do 4 deep cycle 6 volt for the RV. 2 ea in parallel, then the two "sets" in series. Should give me a good amount of Amp Hours, They are just so darn heavy.

Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

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Post Thu Apr 19, 2018 9:42 am

Re: My '89 9670 build

No. those are group 31 12 volts in parallel, not the normal starting group 31's but deep cycle. 540 amp/hrs. The cabling is 4 ga which is overkill for something that will never see in excess of 100 amps.
What amp/hrs are you looking for? There are some big 12's made, but it depends on what space you have to house them.
On my Marmon and little cabover I use floor scrubber batteries that are slightly bigger than Gp 31's, mostly taller and they are 155 amp/hr per battery. If you can go over 14" tall you can get batteries in some serious amp/hr ratings. Once you go that big, they make 6 and 12 in the same size, with the 12's being 1/2 the amp/hr rate of the 6's. In that case it matters little which way you go, 4 sixes like you describe or 4 12's all in parallel.
The Marmon battery box has no trouble handling the taller Floor scrubber battery, but the cabover box cover doesn't fit on correctly with the taller batteries installed. I went with three of the taller ones on the little cabover, because of the Maxwell supercapacitor, it took one battery "slot" leaving only three slots left and I wanted the maximum amp/hr's I could fit. The big bunk cabover has air start, and so has 4 open slots, I went with the correct battery group (31) for the box, and they are 130 amp/hr per battery. With 4 I have more capacity in the big bunk than the small even tho each battery has less capacity.
My battery dist has six volts up to 420 amp/hr and 12 volts up to 220 amp/hr (both take the same "footprint", being 15" tall and a little over 15" long.

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Post Thu Apr 19, 2018 9:46 pm

Re: My '89 9670 build

The fellows on the Solar sites make a big deal of only being able to go to 50% of battery amp hour, In, a 12 volt system, no matter 12 volt or two six volt in series. They also talk about the "12 volt" system should only go to minimum 12-12.2, which they say is at 50%. I like the idea of Deep cycle batteries, because they will stand up to more cycles of charge and discharge and seems to be able to stand a "deeper" discharge below 12 volt. It has been 40 years since I really did the "battery" thing in the military.
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