95' Junker Drag Truck

[Lostnwalmart]

Im excited to see this thing in the 10's!

 

[12vriviera]

just a different secondary than he had, and this head and cam... yeah that will do it!
Will, I am too lazy to remember or read back, you doing a different ppump as well?

 

[Big Blue24]

Will, was your head cut for dual springs or did they fit in stock spring seats?

These springs will fit a stock head with zero cutting or modifications. If you want to run a valve seal (I do) then you need to buy the LS1 application viton seals for around $25 and borrow or buy a cutter $80-$120 to install the narrower seals.

just a different secondary than he had, and this head and cam... yeah that will do it!
Will, I am too lazy to remember or read back, you doing a different ppump as well?

The motor will be reassembled and run with the identical pump, injectors, and turbo combination to get some base-line numbers to compare the added benefit of home-done porting, polishing, back-cut valves, cut pistons, upgraded valve train, and aftermarket camshaft.

After a few passes, and/or dyno runs, the plan is to first increase the delivery valve size and injector size to see if we can eek a little more power out of the 160 pump. After those modifications, I'll swap out the injection pump for a 215 pump that is sitting on the shelf, ready to install.

If/when I feel that airflow is the limiting factor, a new compound turbo setup will be constructed utilizing an HT80 atmosphere turbo compounded with an undetermined secondary turbo, maybe a custom hybrid He351, S363, or similar small turbo.

 

[12vriviera]

Nice!

 

[straight 6 roar]

Is this the method for machining the head for "top hat" style seals? I think I'm leaking oil down the stems

 

[Big Blue24]

Intake porting:

Inside the intake shelf, there are a few bumps and minor restrictions to flow. In my opinion, this bump near the #1 intake runner is insignificant compared to the overall runner size so I'm not planning to remove it, just cut it down a 1/4" or so.

Another common problem with ported cylinder heads is the loss of swirl on the intake ports when the porting is taken too far and the swirl ramps are removed. On a maximum effort engine, idle haze, poor throttle response, and loss of bottom end horsepower are not a consideration and flow is the only goal.

On this head, I'd like to maintain as much swirl as possible in hopes of maintaining excellent spool-up characteristics for those times when the throttle is lifted to regain traction and slow spooling would cause the race to be lost.

Stock intake port:

Mildly ported intake bowl:

Stock intake swirl ramp:

Mildly ported swirl ramp:

 

[murphy41]

On the back cut valves, do you plan on doing a 5-angle seat or anything like that as well? And are you using stock valves, or going to experiment with oversize valves?

 

[Chrisd91]

Is this the method for machining the head for "top hat" style seals? I think I'm leaking oil down the stems

Curious on this as well, I'm having problems with seals leaking since going to compounds

 

[Big Blue24]

Finished up the intake porting using a long carbide burr to reach deep into the intake ports.

This head retained 75% of the original boss and swirl ramp, just removed minimum required to clean up the transition from runner to bowl.

The crack prone bridge area between the valves and injector passage was cut down and rounded to hopefully reduce the surface area exposed to high cylinder temps to reduce the amount of future cracking. Every bit of metal removed here lowers compression so I tried to remove as little as possible.

 

[Big Blue24]

The last step in preparing the head was to perform a make-shift valve job. The old valves have worn depressions in the seating area that restrict airflow at low lift. The seating areas are also pitted and no longer sealing well.

The first step was to regrind the stock valves to provide a flat surface at the seating area. This task was performed using a small mini lathe and a flexible grinding attachment for a small bench grinder clamped into the tool post. It's probably not what a professional shop would use for valve grinding, but it was free.

I don't have an easy way to re-cut the stock valve seats. Luckily on this head, the stock valve seats were in great condition and only needed minor lapping to clean up:

The fresh-cut valves lapped right in with just a little bit of hand work on the valve lapping stick.

The valve seat cleaned up quickly as well:

Next I marked the valve face with a sharpie permanent marker to create a dark contrast at the valve seating area.

Then I dropped the valve into the head and gave it a couple short turns back and forth to mark the actual seat location on the valve.

The exhaust valve seat is 45*, so I added a 60* back cut to increase flow by providing a smoother transition into the valve seat and by feathering-in the transition between the valve stem area and the valve seat cut.

Next a 30* cut was added to the other side of the valve seat smooth that transition and increase flow:

The valve seat width was set to the minimum end of factory specs at .060", too narrow and the valve will burn up because it won't have adequate contact area to transfer heat.

It doesn't look like much but those little cuts do actually make a difference.

 

[murphy41]

Well done Will. Pretty Impressive, I think I wanna tackle this with my head while the motor is out. I currently have .010 over valves, 5-angle seats and only exhaust relief porting. So this would be a good addition.

What RPM does your tool you used run at ? And where did you get the long Carbide bur if you dont mind sharing?

 

[Ghostman]

Awesome work.

 

[Big Blue24]

Well done Will. Pretty Impressive, I think I wanna tackle this with my head while the motor is out. I currently have .010 over valves, 5-angle seats and only exhaust relief porting. So this would be a good addition.

What RPM does your tool you used run at ? And where did you get the long Carbide bur if you dont mind sharing?

Variable speed bench grinder 0-10,000 rpm, if I had to guess, 6500-7000 rpm was the speed I was using and the lathe was spinning the opposite direction around 250 rpm.

 

[AsTroSS]

Why you keep swirl sharp edge?

 

[Big Blue24]

Why you keep swirl sharp edge?

I wanted a sharp distinction at the incoming air from the runner and swirling air leaving the bowl. In my mind, with a rounded edge, there would be more turbulence as the the incoming runner air would try to follow a rounded edge more than a sharp corner.

 

[jlbayes]

sub'd

 

[Newdieselguy]

Nice work!!!!!!

 

[Chrisd91]

These springs will fit a stock head with zero cutting or modifications. If you want to run a valve seal (I do) then you need to buy the LS1 application viton seals for around $25 and borrow or buy a cutter $80-$120 to install the narrower seals.




The motor will be reassembled and run with the identical pump, injectors, and turbo combination to get some base-line numbers to compare the added benefit of home-done porting, polishing, back-cut valves, cut pistons, upgraded valve train, and aftermarket camshaft.

After a few passes, and/or dyno runs, the plan is to first increase the delivery valve size and injector size to see if we can eek a little more power out of the 160 pump. After those modifications, I'll swap out the injection pump for a 215 pump that is sitting on the shelf, ready to install.

If/when I feel that airflow is the limiting factor, a new compound turbo setup will be constructed utilizing an HT80 atmosphere turbo compounded with an undetermined secondary turbo, maybe a custom hybrid He351, S363, or similar small turbo.

What's your take on different turbine options for the he351cw. I've been looking at the 70/60 and the 76/64 10 blade. My understanding is that 64mm inducer is about the largest that will physically fit without intruding into the wastegate passage

 

[Big Blue24]

Next I honed the bores to deglaze and remove a few of the surface scratches. The bores didn't entirely clean up, but it's good enough for a low budget freshen-up.

Before:

Honing tool = 3 stone spring hone powered by my cordless drill, I tried to turn the hone at about 200 rpm and guess my plunge and return speed to produce 30-45* angled cross hatch. Once again, this isn't scientific but good enough for this motor build:

After a couple of minutes on the worst bore, #4, the glaze was removed and a few of the vertical scoring marks came out but the ring marks at the top of the bores are clearly visible. The non-intercooled pistons I'm rebuilding with have a different upper ring groove location so the ring won't even touch the upper worn area.

You can see by the color variations that the bores aren't perfectly round and uniform but without the proper torque plate to distort the bores and simulate a torqued down head, it's best to lightly hone and move on.

Next I welded up the crank gear to make sure it wouldn't try to shear the pin and rotate a few degrees like it did last time. There are (4) somewhat evenly spaced welds. I didn't use filler rod, simply melted the gear and crank together. It probably won't take much to keep the gear stationary.

Next I started working on the block removing the old gasket material and using compressed air to clean out the oil passages.

The Victor Reinz lower gasket kit came with new piston squirter jets, so they were installed before the main bearing upper shells were installed:

I picked up a couple of bottles of Lucas assembly lube from the local Autozone. I think these were about $4 per bottle a few months back when they were purchased.

Upper shells installed, I decided to reuse the original main bearings because they were in great shape.

Then I lowered the crank into place, I had to use a small cherry picker to delicately lower the crank. You'd have to be pretty strong to gently lower the 150# +/- crank into the block.

The main caps with old lower bearings in place. These bearings do show some wear, but I elected to reuse them to save money for other upgrades. I've got quite a few pictures so we'll see how they look in the future if this motor is ever torn down again.

Since this is a 95' original motor, it came from the factory with 14mm main bolts. Although, if you look at the shanks, they aren't much larger than the newer 12mm main bolts on the 96+ motors.

All torqued down, the crank spins freely like it should:

Cummins recommends the mains be torqued in (3) steps: 44 ft-lbs, 88 ft-lbs, and 129 ft-lbs. Just like the head bolts, I over torqued the mains in 5 ft-lb increments starting at 130 and took them all up to 150 ft-lbs. It's true that you have to be careful with warping parts by over-torquing and causing bearing clearance issues, but I felt that the added safety factor of 150 ft-lbs out weighs the minor risk of a tight bearing, especially since the bearings are used and have more clearance than they started with 250,000 miles ago.

 

[kole32]

Do you loc-tite the main bolts ?