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slowpoke · 07-20-2018, **(Subject: top end set )**

when checking top end set. do the valves normally tighten up or get looser under normal conditions. the reason i ask is i thought they would tighten as valves sink into head. but mechanic
that did it for me said that it's opposite and they will loosen up. so after talking i opened it up and redid them to 15tho on intake and 29tho on exhaust but didnt touch injectors no tool for it yet. was i wrong in doing this probably should have asked first, but not my style lol
( cm871 m^m^2 program by uni )

Nilao · 07-20-2018, **(Subject: top end set )**

They tighten up...at least they did on my engine. My exhaust rocket was riding on the valve stem when rawze helped me to mine the 1st time.

Rawze · 07-20-2018, **(Subject: top end set )**

(07-20-2018 )slowpoke Wrote: when checking top end set. do the valves normally tighten up or get looser under normal conditions. the reason i ask is i thought they would tighten as valves sink into head. but mechanic
that did it for me said that it's opposite and they will loosen up. so after talking i opened it up and redid them to 15tho on intake and 29tho on exhaust but didnt touch injectors no tool for it yet. was i wrong in doing this probably should have asked first, but not my style lol
( cm871 m^m^2 program by uni )

They tighten up. Your mechanic is a dumbarsse. It is not the top of the valve stem that wears, but rather the valve seat.

slowpoke · 07-21-2018, **(Subject: top end set )**

just found this guy, he was supposed to be an expert on cummins but it was other things he said that contradict a lot of things I've read here. like boost should be 45psi. it was hard to check valve lash without loosening set screw but i found 3 exhaust valves around 15 thou. have 50000 on fresh engine. so i'm back to no mechanic. thanks, so what i did is fine. 15 and 29

slowpoke · 07-21-2018, **(Subject: top end set )**

you know its funny because he said exactly the opposite, almost word for word "its not the valve seat that wears but the the top of the valve stem"

Rawze · 07-21-2018, **(Subject: top end set )**

(07-21-2018 )slowpoke Wrote: you know its funny because he said exactly the opposite, almost word for word "its not the valve seat that wears but the the top of the valve stem"

Maybe in an old engine form the 1970's with push-rods in it,.. but not no ISX there chief!. Never seen it happen and I have done hundreds of them. -- The camshafts usually wear out faster than the top of the valve stems and/or cross-heads do.

Not sure if I would have gone with 0.029" on the exhaust valves myself. They already have good clearance for oil flow at 0.027". The 0.015" is fine though for the intake valves if your goal was to ensure good oil flow to them.

07-22-2018, **(Subject: top end set )**

isx valves tighten, anyone who works on them would know this. As for the 45 punds booost, people are so stuck on this dam boost number. its about flow and physical amount of air through the engine. If i had 2 turbos that put 80lbs of air a minute through a engine, one did it at 50 psi and one did it at 25 psi the 50 psi turbo would blow the engine up and the 25 psi turbo would be awsome. yet everywhere you would go everyone would tell you your boost is too low. ITS ABOUT FUCKING FLOW, NOT BOOST PRESSURE WORLD GET YOUR shi#t STRAIGHT.

sry bout my rant just had to many dumb converstations lately about boost.

hhow55 · 07-23-2018, **(Subject: top end set )**

That is why it is so important to have oem cac, and not the aftermarket one's that are so restrictive on air flow.

Rawze · 07-23-2018, **(Subject: top end set )**

(07-22-2018 )Unilevers Wrote: isx valves tighten, anyone who works on them would know this. As for the 45 punds booost, people are so stuck on this dam boost number. its about flow and physical amount of air through the engine. If i had 2 turbos that put 80lbs of air a minute through a engine, one did it at 50 psi and one did it at 25 psi the 50 psi turbo would blow the engine up and the 25 psi turbo would be awsome. yet everywhere you would go everyone would tell you your boost is too low. ITS ABOUT FUCKING FLOW, NOT BOOST PRESSURE WORLD GET YOUR shi#t STRAIGHT.

sry bout my rant just had to many dumb conversations lately about boost.

Very well said. I think a lot of people also don't realize that it can take as much as 10% less boost pressure on some engines to make the same power/torque when an engine has been de-mandated. This is due to more oxygen getting into the cylinders. Combine that with a higher AR ratio because there is now no flow being bypassed between the exhaust to the intake(egr blocked), and things can sometimes need to be lowered by quite a bit.

The recommendations that I myself make on this forum about boost pressure are based on factory Holset VG turbochargers, lots and lots of testing, and seeing literally hundreds of failed engines by bad programming that has been done by the so-called "experts" off those various auto tuning forums, social media sites, and the hundreds of various butcher shops doing sich things across the country. I have seen my share of damaged engines because of stupid people out there doing stupid things and giving bad advice. Most of these "experts" simply don't understand how these engine actually even work.