Guess the issue!?

kyle43335

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Thats what I was getting at, you need to shim the spring in this instance right, or at least once you have taken enough off I would think it would be worth it.

Regardless though, I'll be able to measure protrusion tomorrow and I believe thats where our contact issue lies. The compression issue was the valve and the contact issue being the deck was ground by the pistons were not.

more tomorrow!

your not taking enough material off to really affect seat pressure to the point,causing your issue.

where this senario would be valid,is at wot. boost and drive pressure overcoming seat pressure blowing the valves open.

check this out once.

piston protrusion is around .030
a oem gasket has a installed height of around .052

some of the bo gaskets ive measured back in the day were .010 or better thinner than stock(oem)

pp .030
+ .010 deck the block(this would be a estimate. could be more)
--------
.040 piston above deck
.042 this is per layer measurement. (uninstalled height) gasket compresses roughly .008 thou.



just doing the math with the bo gasket uninstalled,you have .002 thou remaining.

if you take the rough .008 that the gasket will compress? that drops you to no clearance.

the pistons still have the identifying words and size in the face,indicating that they didnt have any material removed to compensate for the block decking.
 
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Derek@Vision Diesel

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You get my text back? Our cell towers went down locally.
No I didnt bud
your not taking enough material off to really affect seat pressure to the point,causing your issue.

where this senario would be valid,is at wot. boost and drive pressure overcoming seat pressure blowing the valves open.

check this out once.

piston protrusion is around .030
a oem gasket has a installed height of around .052

some of the bo gaskets ive measured back in the day were .010 or better thinner than stock(oem)

pp .030
+ .010 deck the block(this would be a estimate. could be more)
--------
.040 piston above deck
.042 this is per layer measurement. (uninstalled height) gasket compresses roughly .008 thou.



just doing the math with the bo gasket uninstalled,you have .002 thou remaining.

if you take the rough .008 that the gasket will compress? that drops you to no clearance.

the pistons still have the identifying words and size in the face,indicating that they didnt have any material removed to compensate for the block decking.

So with a factory gasket it possibly could have worked as is, but still in my opinion .004 (which is the clearance with .010 off the block and the gasket compressed) is not enough clearance. So this block would either be junk or needs disassembled and some material shaved from the pistons.

I will definitely get some better number tomorrow when I have the right tools to measure protrusion.
 

kyle43335

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No I didnt bud


So with a factory gasket it possibly could have worked as is, but still in my opinion .004 (which is the clearance with .010 off the block and the gasket compressed) is not enough clearance. So this block would either be junk or needs disassembled and some material shaved from the pistons.

I will definitely get some better number tomorrow when I have the right tools to measure protrusion.

could have worked.

normal clearance with .030 pp and .052 compressed hg thickness is .022 thou
 

Mdub707

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Yeah .004" of clearance doesn't exactly leave me feeling warm and fuzzy. I'd be nervous as ***k to run that.
 

Derek@Vision Diesel

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Well we finally measured protrusion and it seems as though we have bend rods OR a deck that was not machined flat.

#7 had .005 protrusion.

#1 had .030 protrusion

#3 had .027 protrusion

#5 had .020 protrusion
 

Derek@Vision Diesel

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Pulled the drivers side head today to see if anything new would pop up, just a couple indications of valve to piston contact once again. The machinist that had these heads last must of either been in a bad mood or straight out of high school. I believe over half of the valves arent seating correctly and they are machine offset in the seat, to me it looks awful and I am obviously no professional
 

Big Angry Hillbilly

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I am obviously no professional

ImageUploadedByTapatalk1347487758.969849.jpg
 

Derek@Vision Diesel

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#7 and #8 rods are perfectly straight. Bearings look great as well

Going to re install and check protrusion one last time, if it is in fact what it was the other 20 times I measured then this block has seen better days.
 

Mdub707

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Sounds like they decked the block with a angle grinder :fustrate:


Seriously, that may not be far off, they probably hit the block with it still in the truck and did it by hand or with a power tool of some sort to "smooth" the block out.... yikes.
 

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