Hi!! I was looking at the Nebraska Tractor Tests book and look at both of the test for the 7U. The early test had the engine running at 1400 rpm and I do not remember the HP and the late test had the engine running 1600 rpm and about 10 more HP than the early test. Was the engine speed change all that was changed or are there other other changes and at what serial numbers were the changes made.
Thanks
Ken

Hi Ken,
They didn't change much, just cranked up the rpm's.
Did require a governor spring change and torque spring change.
The changes were done at 7U 26583 and 6U 9807
The increased rpm's also required the addition of a gear driven balancer mounted at the front of the block.
You can usually readily spot these engines by the extra bulge for the balancer and longer belly pan mounting bosses.

Yes there are some changes to gain more power & speed like a different gov. spring & different fuel rack settings & RPMs. Also later D315s like the D4s used had engine balancers in them.I don,t have any late specs on the D4 but the D315 industrial engines go up in the book I have to 1800 RPMs full load & 1970 RPMs high idle (no load).

Hey OM or SJ, any ideas on what they did to the 112 grader to get more hp out of it or was it similar to the later changes in the D-4? My 112 is a 3U1457, 1949, and my D-4 is a 7U10164, 1950, yet the 112 runs higher RPM and just recalling from memory it has about 12 more hp than the D4-7U. The rpm difference is quite noticeable but I have never tached either one.

The 112 has 24 HP more than the D4 6U & 7U in the earlier days. THis is due as I mentioned before to different rack settings & different gov. springs & RPM setting. The D4 is 1400 RPMs full load & the 112 is 1800 RPMs full load. D4 HP is 51 & the 112 is 75 HP.Rack setting for the D4 is .200 with a 5F6413 spring & the 112 is .350 with a 5F1940 spring & both are with a 9F4113 counterbored fuel nozzle.

Hi Jim,
The grader followed the set up of the industrial, marine and electric set specifications for more power. It wasn't until 1954 that the balancer was utilized.

SJ,
I don't follow you on the 9F4113 counterbored fuel nozzle. These being the capsule type injectors.

Rack setting specs attached:

OM, I just turned my high idle up to 1,600 without messing with any thing else. Am I asking for trouble by doing this? Or just not making more power? But usually I don't run it faster than about 1,300rpm so the hydraulics aren't so jerky.

Hi Mike,
If your just going from 1525 to 1600 rpm high idle, I don't think your going to hurt anything but there wouldn't be significant change in power.

OM, I never really knowed what changes there was in the counter bored nozzles from the other ones but usually what I remember the tips did have a counterbore where other ones had a flat end on them. Take the 212 we,re talking about they list both nozzles for the same engine & the 9F4113 C.B. nozzle in that engine uses the 5F1940 gov. spring but the rack is set at .350 & the high idle is 1980 RPMs.The 4F4236 regular nozzle is listed at a .235 rack setting & 1950 H.I. & it also uses the 5F1940 gov. spring.Both setups put out the same HP at the same full load RPMs of 1800. Most the nozzles or replacements were the counterbored tip style as I remember.I guess we,ll have to ask the big yellow father where the changes come in, that was our joke when we were working at the dealer.The info (specs), I got them from a Cat rack setting book that I have using the 3H1690 rack setting gauge which is what I always used.Your question got me to thinking, well what is the difference in the two nozzles but there has to be some internal change I,m sure but never saw the differences or don,t know where to find an answer.

Hi Team,
the counterbored nozzles I believe are first mentioned in Service Magazine May 31 1951 page 32 for 4"-4 1/2" bore engines and a drawing is showing that the nozzle orifice bore is larger in Dia. from the valve seat to just before the outlet where it reduces down to the true orifice Dia.. The old style nozzle bore is the same Dia. from the valve seat to the outlet. It goes on to say that this was done to reduce carboning and the subsequent plugging which results in a reduction of power , or misfiring. This is particularly noticeable on heavily loaded engines. In addition to the counterbored orifice, a steel jacket of greater strength has replaced the original copper jacket.
The latest article I am aware of on this subject is Product Bulletin March 02 1962. There are others for different bore engines over a period of time.
Regards
Eddie B.