Hunter: I will sell D5 98J 492. I wanted to sell 759, but it has the 333 NA and cable blade. JM

The Variable Horsepower model D5 didn't kick in until the D5B.
I suspect they didn't get turbo's because you'd run out of traction before you ran out of horse power.
For comparison....
 

I am thinking you are in California but if the tractor came from the Palouse I would suspect it has been turned up substantially over stock setting. I have been told that the dealers were turning the turboed 3306 tractors up to around 180 hp if they were wet decked. Much more and the finals became the weak link. I have spoken with several local farmer’s who purchased new 21J and 98J tractors that had the dealership add turbo and turn them up after the first season. Even the grader kit, turboed and turned up to 18-1900 rpm 9U’s were supposed to be about 120 hp on a lighter tractor. Hard to sell new ones that could not outwork the old one. Not sure that Cat was really trying to compete with the 1673 hot rods at the time. Traction I know is a limitation at some point but most of the time the extra power matched to the same tillage equipment was to avoid the constant shifting on the hills. I have a few to hobby farm with mainly because I can remember wanting dad to get one when they were new. I guess after all of my rambling what I was trying to say is that after 50 years what the tractor is capable of has more to do with what the last mechanic did than how Cat shipped it.  Pictures please when you get it. Mike 

Speaking of grader kit the old D318 in the #14 B Series Grader with turbo (last of the D318's) were rated at 150 hp.
 

 

That is interesting, do you happen to have the spec sheet for a 9U, I wonder what rpm the stock engine was set at, I am thinking around 1600?  I think that in addition to turbo and bigger pumps in injection pump that the pistons and perhaps oiling for the piston skirts were different. Thanks, Mike


 

The early 9u was set at 1400. I believe it was very close serial number 13xxx where the oil clutch and other updates where added, they up it to 1600 RPM.

I started with 9u 23xxx and it was not at all snappy, more like a 4r I had run for the neighbors. Finally got one of the old guys to come tune on it, it was not much more than 1400RPM's. We ended up setting it to 1700 RPM's, made a different tractor out of it. Several others that had run a number of 9u's said one of the best pullers.

In the last years a earlier 9u came here 70xx. It has a much larger than needed dry air cleaner and pulls as well if not better than my first. A bit of history says it was part of a fleet of farm tractors tended by the local expert not apposed to turning a Cat engine to get more out of it. Also seems to suck up more fuel. Since I don't run them much and most need a lot of TLC, I never had them running at the same time to really prove anything.

Reading the service manual for the D 318 engine in the DW 10 scraper tractor with a different fuel pump/govern they are set to 2100 RPM.

So tuning can make a deal of difference in how much work you get out machines in the same serial number group.

Here's the rack settings on various units with the D318.
I will post the #14 rack settings later.
So far in checking comparison for the #14, the pistons are the same 4-ring cam shaped ground units used on the late 9U's.
Rods are a different part number
There are no oil cooling jets for the pistons like later turbo models.
Injection pumps are the same 8mm units as used on the late D6's
Uses a different governor
 

 

#14 Series B Grader with turbocharged D318
 
 

After some searching I found this “Performance Handbook 42”. Here is a link perhaps this information will be helpful to others the D6 98J was listed under “Former Models”. Also here is a screen shot of some of the info I was looking for.  

www.puckettmachinery.com/system/resource...rmanceHandbook42.pdf
 

Thanks for posting that OM, I have never messed with any of the pumps myself but if I read it correctly the larger the rack setting number the more fuel that is provided? Ray that was interesting about the air cleaner, mine all have dry D5 air cans and I have heard people claim that the D6C 3306 tractors gained power and ran cooler once the air intake was reworked to larger plumbing and larger air cleaner it would be cool to find one of the test tools that cat used to measure drawbar pull to actually see and compare what my different tractors are actually doing. I have one 9U with pretty low hours that I was always disappointed with until I realized that it had higher transmission gears than all of the others I had been around, pulls really good in second gear which is somewhere in between third and fourth on the others for ground speed. Thanks for the info, Mike