We have a Case 4694 with 10,000+hours on it that we use for spring and fall tillage. We bought the tractor in Jan 06, it never seemed to have an abundance of power and smoked excessively black. In the fall of 2012 it spun a rod bearing. The Winter of 12-13 We completely rebuilt the engine; new sleeve assemblies, new injectors, had the pump rebuilt with new barrels, new turbo. Spring of 2013 it smoked even more and does not seem to have the power it should. This winter we have double checked the valve timing; valve movement distance,as well as the pump timing; put a intake manifold from a 2470 for testing purposes, and it still seems to be the same. It only seems to build about 6 psi of boost. Any Ideas?

Check the fitting on all the connections where plastic connections are. On our 4690 a reinforcing ring that is used to keep tubing fromcolapsing had turned 90degrees an was blocking air flow. Been a while but fitting was near radiator cross over.

We always set the pump timming at 31 deg.BTDC,I think the original spec was 25 deg.BTDC

I agree with the others,it sounds like you have a severe air blockage some where, also you may want to look at the turbo itself and make sure that it is working properly as you should have alot more than just 6 pounds of boost.

Rent a timing light from Spencer Diesel (712)262-5267 Actual/running timing prob off 5 to 9 degrees from static. Joel at Spencer's will explain the situation, john

take the inlet tube with the precleaner off and clean it out, my 2470 had the same problem, on the dyno it only had 90hp and smoked like a profarm tractor puller! mine was plugged with a mouse nest,

I have a boost gauge in my 1570, have never loaded it right down but it will make at least 25lbs under a good load.
Ben