[orange1954]

What is the general method to repair or tune up the valve seats? And is it something that can be DIY, or is a machine shop a must? Are the seats replaceable? I can't seem to find much info on this forum, let alone even on the G00gle. Will a simple valve lapping be sufficient. I may replace the valves.

 

[char1355]

These heads have replaceable valve seats. If they aren't totally shot, then a touch up with grinding stones and lapping would be OK. The lapping you may do yourself but most of us aren't equipped to do grinding. If the seats need replacing, that's definitely shop work. Just for your info, the seat are Cummins part # 3904105 for exhaust and 3906854 for intake. The valves themselves can also be ground. If they are too bad then you replace them. The inserts can be found in the $6-10 range each. Replacement valves aren't big money either. If any higher performance is planned, changing to HD valve springs would be advisable. Also, inspect the head for cracks. Heads that had the 9mm injectors were notorious for cracks.

 

[orange1954]

I assume by HD valve springs, you're referring to the "white stripe" or 60lb springs. #3916691
Do I need to do both intake and exhaust springs?
Both the intake and exhaust valves use the same spring, correct? Many searches seem to call the above spring an exhaust spring.

Unrelated to this thread, but are 3000 gov springs for a 4BT VE pump the same as on a 6bt?

Planning to do the "200 HP recipe" from another thread. (hx30w, intercooler, pump fuel up and 3000/3200 governor spring.)

 

[Nascarmark]

Yes, the white stripe/60lb over stock is the 3916691 springs.
You don't need to use the 3916691 on intake & exhaust but there is some performance to be had by doing so.
There is no such thing as 3000 gov springs for a VE Inj pump. There is a 3200 spring though & yes, it is the same spring for a 4bt & 6bt VE pump.

 

[char1355]

Nascarmark is correct. You don't really have to put the HD springs on the intake but most guys do. One of their primary uses was on engines with exhaust brakes. Main issue is the possibility of floating a valve at higher RPM. Most of the sets you see are in 6 or 12 springs. They aren't big bucks.