1086 oil pump

I've install a 1.25'' oil pump on our 1086 2 years ago to solve low oil pressure at idle, when I installed the balancer it would not go into the seal housing enough to keep it from seeping oil, I have since read somewhere that there were 3 widths of oil pumps used on the 400 series engines the 7/8''& 1''were used on the B engines and the 1.25'' was used on the later C engines, the 1.25'' from what I gather can be used on the B engines but the balancer has to be machined to accept it, and possibly and over size sump tube installed, does anyone have info. as to what changes were make to use the larger pump and possibly photos of the upgrades, this tractor was bought with a bad oil pressure gauge after finding that and that the oil pressure would barely move off 0 on a mechanical gauge at hot idle, 35 psi full throttle, I swapped out the relief valve no change, then I replaced the pump it had a 1'' pump no change, so I dropped the pan replaced the bearings rods didn't look all that bad and the journals measured to factory new tolerance, mains were worn and one had a wide grove that appeared to have been washed across it, but the best I could measure the journals the were also to spec,i double checked then with plasti-gage it showed the same, I checked the cooling nozzles they were good, even with all this and the larger pump I have 15 psi at idle hot 50 psi at anything above 1/3 throttle, I suspect the cam bushings are part of the problem but that's a major tear down which I don't want to get into as long as it starts and runs as strong as it does now unless someone can tell me what I missed, if I can fix the leak I going to run it like an old Detroit diesel, high volume low pressure until it gives up, thanks in advance for any info on the low pressure problem or pump size upgrade

I just overhauled a 1086 a year ago and it carries 65 hot 25 at idol and I use the old relief valve over I talk to another person he told me to not put that extra wide that was made trucks because air compressor and the oilers on rocker towers to oil the cam sound crankshaft war and camshaft before I overhauled it it carried 40 pounds wide open and ki I overhauled it carried 40 pounds wide open and 10 When Tore it down I had broken rings cam lobes wore just like a Chevy If you overhaul it trying to find a truck rocker arm for C series I use reliance sleeves and pistons had to crank turn new cam lifters had a hole side lifter for extra oiling and camshaft I used 1 in oil pump in 42 years I work red tractors 400 Series had bad oiling to the cam we had 1086 200hp now at 150 heat Does lot with oil pressure

I wonder what oiling system your rocker arms are using. There are three different types. Original merely had a small v cut in the bottom of rocker arm pedestals. Next was oil jets on a three pedestals. Last and best had a nozzle on each pedestals. All of these are to run oil down to the camshaft but the ones with all six having nozzles can use considerable more oil flow so this could have some effect on low idle oil pressures. Maybe someone even installed the larger oil jet used on one pedestal on earlier changes. Off the top of my head, I think the larger jet was like .080 and smaller ones were .060.

At any rate, if you have 15 psi at low hot idle and it immediately increased with some rpm's you have no worries. Only good way to determine the reason for lower pressure than other engine with same exact modifications on that engine, would be to do a pressure tank flow with pan removed. Messy and time consuming but you could see if you had some significant oil flow where it should not be. Might even be the bore pressure regulator fits into the block.

How many hours you got on this tractor with this pressure I will just run till she dies I?ve seen worse