I am rebuilding an International D239 from a 574 Tractor. When I received the tractor it had leaking sleeve seals allowing coolant into the crankcase. I have the engine disassembled, and all of the main, rod, cam bearings have extreme wear so I am replacing bearings, sleeves, pistons, rings. I ordered parts from All States Ag Parts (Reliance) and just received the parts. My current confusion is with the cam bearings. I read that the cam bearings come unfinished and must be line bored so I was expecting an unfinished bearing but the part that arrived is a finished bearing. The part number sent is a 3055008R2 on the package. I test fit the bearing and it felt very loose. I then measured the inside diameter and it is 2.292". The measurement of the Cam journals is nominally 2.2825. The D238 service manual states that the max running clearing is .0045", and it lists the journal diameter as follows:
Engines with Tin-Babbitt cam bearings 2.2823 - 2.2835
Engines with lead-bronze cam bearings 2.2813 - 2.2825
Why would the finished bearing size be 2.292? The only thing I can think is that finished bearing was intended for engines that originally had Tin-Babbitt bearings because in those engines the cam had larger diameter journals?
My cam appears to be in spec at 2.2825 so the running clearance with this new bearing would be 2.292 - 2.2825 = .0095? This is way out of spec according to the service manual (max running clearance of .0045). I assume at this point that I will need to return these finished cam bearings and order unfinished cam bearings and have them line bored. When they are line bored how much clearance should the machine shop allow between cam journal and bearing?
The IT Shop Service Manual states: Camshaft Bushings are furnished semi-finished for service and must be line bored after installation to an inside diameter of 2.2844 - 2.2856. Normal operating clearance of camshaft journals in bearings is .0009 - .0033 with a maximum allowable clearance of .0045.
According to the above, if machined to 2.2844 (smallest size mentioned) the running clearance would be 2.2844 - 2.2825 = .0019. This seems reasonable and is within the spec.
Thanks for your replies.