G188D engine performance

[Travwm]

Hi guys. I have a 1963 case model 53 and a 1967 case model 430 both utility tractors have the G188D diesel engine and the difference in performance is day and night. The 1963 has all kinds of power and torque and the 1967 is just very lame. Both tractors have roughly 5000 hours on each.
Any ideas as to why there would be so much difference in power?
Both engines have had the injection pumped rebuilt

 

[jon f mn]

The pumps have significantly difgerent settings. Have the 430 pump set to 530 specs. And check the timing, timing is very precise on those. Make sure you set it exactly how the book says.