Young gun's 94 build thread

[12vCumminsFTW]

You'll bust a nut. 1498$ out the door, and NO they did not use chinesium.

Certified Injection Service out of Salt Lake City built it.

Hmmm I could afford that lol. Anything else done to it besides 13mm p&b? I'll be interested to hear how it runs.

 

[Chrisd91]

Who did your pump? It sounds strange that you only have 100cc of adjustment? Also are you will to sell the hx82?

I think the DVs are the limiting factor for upward adjustment

 

[YOUNG GUNS15]

Hmmm I could afford that lol. Anything else done to it besides 13mm p&b? I'll be interested to hear how it runs.

Just the 13mm and the cam out of my 215. Of course 5k springs, rack plug etc

 

[YOUNG GUNS15]

Installed factory bypass block (usually used for heaters on buses)



Painted



And that's about as far as I got. I ran into some issues with the valve reliefs, Intake valve won't sit into the pocket, you can see in this picture the stem of the exaugst sitting lower than the intake.



Put some assembly lube on the valves and compressed the springs so I could feel what the valve was doing, exaghst valve sinks in while the intake just barely hits the edge of the relief.



Another picture showing the same thing, just printed on the head with no head gasket. As you can see, exaugst fits into the pocket well, intake hits just barely.




As of now I have the pistons all removed to be fixed. Frustrating is an understatement.

In other news I CC'd the bowls and reliefs and they came out at 50.5cc for whoever is wondering. I used a syringe and filled the bowl and relief with water and recorded how many CC's it took. Pretty simple stuff.

 

[YOUNG GUNS15]

I also want to put this up for discussion, my piston protrusion is measured at .027, I'm being told that's about .010 too much. I've found where cummins spec is .024-.028, what do you guys think? I really don't want to cut the Pistons MORE and loose even more compression.

 

[Ghostman]

What's the piston to head spec from cummins? I would say that would tell you if the Pistons need to come down some. I believe a stock gasket crushes somewhere around .050"? Can't remember exactly.


Sent from my iPhone using Tapatalk

 

[Smokem]

If it is standard bore it would currently be right at 16:1 with the information listed.

 

[YOUNG GUNS15]

If it is standard bore it would currently be right at 16:1 with the information listed.

Cool, I was playing with a calculator online and couldn't get my compression numbers right, I had to assume an 8cc (I think) combustion chamber to get 16:1 flat. Gasket is .065, I think the motor will be fine as far as protrusion. Lots of second guessing since finding out the reliefs weren't going to work quite right.

So if we assume the gasket crushes out to .050 the. Subtract .027 to get piston to head clearance? Correct? That would leave .023 thou. Does that sound about right? I am still searching for a piston to head spec.

 

[ahale2772]

.025 is not far off of what you should be

 

[Smokem]

I tend to err on the side of caution and go low side of the compression scale, this gives room for piston protrusion variance. I would estimate your piston to head ~ 0.028", if you plan to turn it much RPM I would get that value closer to 0.040", remember decking the piston will slightly decrease bowl volume.

 

[YOUNG GUNS15]

I tend to err on the side of caution and go low side of the compression scale, this gives room for piston protrusion variance. I would estimate your piston to head ~ 0.028", if you plan to turn it much RPM I would get that value closer to 0.040", remember decking the piston will slightly decrease bowl volume.

What kind of rpm would justify cutting them down? Motor may see 5k on occasion, I'll be putting a set of compounds on that will keep me under 4500rpm in the future.

 

[TheSilverBullet]

Watching ^^^ my motor build is close to starting. So looks like everyone goes with .050 for stock gasket? Many threads said that but no evidence.

 

[straight 6 roar]

.010 over gasket would be the easy fix but you probably don't want to take that big of a hit on compression.

 

[murphy41]

I tend to err on the side of caution and go low side of the compression scale, this gives room for piston protrusion variance. I would estimate your piston to head ~ 0.028", if you plan to turn it much RPM I would get that value closer to 0.040", remember decking the piston will slightly decrease bowl volume.

Hense the reason I suggested to mill the top of the piston .005-.010 to get the piston to valve to about that .038 range. But will take a loss on bowl volume and compression. Which is why I went with a custom ground cam with a little wider LSA to help compensate the clearance without taking a hit on compression.

 

[YOUNG GUNS15]

finally got on a computer and realized my pics are all tiny.... lol

Pistons have been modified, and hopefully they fit this time!!!! really eager to get this truck on the road. bough some .140 3/8 push rods from Taylor (TMONEY) last week, dang good deal if you ask me! Really the only parts I am lacking now that more of wants than need's are a billet timing gear cover, billet tappet cover, and an adjustable pump gear. Those will have to come later though.

 

[YOUNG GUNS15]

Old



New

 

[97rada]

Different pistons?

 

[YOUNG GUNS15]

Same pistons, just enlarged the pockets and cut that thin piece of aluminum off closest to the edge of the piston

 

[YOUNG GUNS15]

Finally getting somewhere



Welded the injector return down, I think it looks much better this way, it's removable separate from the lifting eye.

 

[YOUNG GUNS15]

5x.020's built by Will Terry



Pushrods from Taylor!







About ready to go in, timing set at 18* temporarily, studs torqued, valves set to .010 and .020 for now, will tighten them to my favorite setting of .008 and .018 after re-torques.


Took a break from sand blasting and painting