Farmall MD/Mccormick WD6 Bosch Injection/IH Injection Pump

When did they switch from the bosch injection pump on the farmall md's/mccormick wd6's to the international injection pump

From the research I have done, looking at production numbers, serial numbers and so on it looks like they switched to the international pump around the the end of the war possibly 45 or even early 46. I have a 43 parts book for a md and it only lists the bosch fuel system. It was after the war that the M series sales really jumped and more people started buying the larger tractor ( better post war economy). Most md were made between 46 and 51. They did make a fair number in 41 probably because it was the new tractor and ih first diesel row crop kind of market show case. There are not many of the early md left mostly because when the md came out people were so use to the kero/distillate tracors and how they operated that the engines were ruined from improper operation( head and block cracking) from improper warm/cool down period. Alot of crawlers used the bosch system up into the early 50's. Personally I think the bosch is a more responsive pump then the ih pump. One thing to keep in mind is the serial number breaks with the injectors as to which pump they are used with.... the bosch injector opens at 1400psi if I remember and the ih opens at 800psi. Hope this helps. Jim.

1945 parts book shows both pumps.

Don"t think there was a clean cut off. In 42 some MD were getting the IH. Plus a Bosch could still be specified for use after the war for some costumers. Something I don"t know about is the higher cracking pressure I see posted for the Bosch injectors. Far as I know the first type injectors IH used on the engines was used with both Bosch and IH pumps. Don"t believe they could be adjusted to the pressure some say over the 700 PSI IH specified. Been wrong before though.