95' Junker Drag Truck

[TrailTamer]

You (or anyone) can always dyno the truck on straight diesel then take the LP's inlet hose into a 5 gallon bucket of WMO and rerun the dyno and compare.

I personally run on WMO as fuel in my DD truck. IMO on either straight WMO or high content of WMO, the power suffers some. I felt much more power on D2 when I ran out of WMO at one time away from home. I think a balance between WMO and D2 there'll be an improvement in power. However I think it can be remedied by monitor it's cetane value and ensure the fuel is hot prior entering the injection pump and an extra bump in timing.

Another problem on WMO that it's content isn't easily kept consistent unless you have a really good source to keep the WMO's content known. Most shop will put used motor oil, gear oil, brake fluid, ATF, etc. in one container. I personally do experience different result in different batches. This isn't as critical for a DD as all I care that I still go from point A to B, while you're not as it's for drag racing.

 

[Nootch]

WMO is a hit/miss now a days with all the SYN that is out there. I used to work with a paving company that used large amounts of WMO to make asphalt. With the increase of syn oil being burnt they have to retune the jets to inject more oil to get the temp they need. If you can get strait weight oil, you are laughing though. instead of WMO, i would try to cut in bunker oil if you are looking for a power/race application. But i don't know the availability of such things in your area and the feasibility of it.

[ame="http://en.wikipedia.org/wiki/Fuel_oil"]Fuel oil - Wikipedia, the free encyclopedia[/ame]

 

[akadiesel]

This is not about WMO. I am after, first, the optimum temp for. Diesel injection, disregarding lube. Oil added and % to follow. Oil will be 30 wt non detergent baseline. No dyno is needed to see 5-10 psi increase at 20-50% oil. When I return home, i will start a thread somewhere and put a link here.


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[crackerman]

This is not about WMO. I am after, first, the optimum temp for. Diesel injection, disregarding lube. Oil added and % to follow. Oil will be 30 wt non detergent baseline. No dyno is needed to see 5-10 psi increase at 20-50% oil. When I return home, i will start a thread somewhere and put a link here.


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No. Its about the junker drag truck. Start your own thread.

 

[Nootch]

Its more my fault for trying to elaborate. I am the one inadvertently hijacking.

Apologies to OP for defiling the last of page 75 and start of 76

 

[akadiesel]

I just said i would. I asked only for his input and prob should have pm'd.


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[Big Blue24]

This is not about WMO. I am after, first, the optimum temp for. Diesel injection, disregarding lube. Oil added and % to follow. Oil will be 30 wt non detergent baseline. No dyno is needed to see 5-10 psi increase at 20-50% oil. When I return home, i will start a thread somewhere and put a link here.


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I honestly have never seen a power increase on my daily driver with added WMO or 2 stroke oil or ATF, I have not played with fuel changes on the Junker (YET) but will play around some in the future.

No. Its about the junker drag truck. Start your own thread.

This is true, back to the motor build......

 

[Big Blue24]

I lubed the re-ground tappets and Hamilton Camshaft with the supplied assembly grease, after first start-up, we'll know if the Joe Gibbs Racing lube works....

Finally got the camshaft installed and ready to degree-in and check the cam timing.

 

[Big Blue24]

For checking the cam timing, the first step is to get a degree wheel. The cheapest method to accomplish this is to print one from the internet and glue it to a piece of cardboard and add a 3/4" hole in the center for the crankshaft pilot.

Then I added a piece of wire under a timing cover bolt to make a pointer:

Next I found exact top dead center using a dial indicator on the #1 piston. I started turning the degree wheel on the crank to where I estimated TDC to line up with my pointer when the piston was all the way up. I then positioned the dial indicator over the center dome of the piston and checked the degree reading on the printed wheel at .010" before maximum piston lift and .010" after maximum piston lift. Halfway between these readings is exact TDC so I adjusted/rotated the printed wheel until my degree readings at .010" were exactly the same on either side of the TDC mark on the degree wheel. Fairly straight forward when you're there doing it.

After the degree wheel is set to where TDC on the wheel lines up with the wire pointer when the piston is at TDC, I relocated my dial indicator over the #1 intake valve tappet and installed a pushrod. I then rotated the motor until I reached maximum lift.

I then turned the dial indicator to 0. Then rotate the motor backwards until the dial indicator made just over 1 full round backwards around -.060" lift, then I rotated the motor forward which removes gear lash and slowly creeped up to -.050" which is 0 on my dial indicator

Now looking at the degree wheel, the wire pointer showed roughly 59*.

Next I continued to rotate the motor forward watching the dial indicator climb one full round back to 0 which is peak lift, then continue to rotate the motor forward and watch the indicator fall one full turn back to -.050" lift. At this location, the wire pointer on the degree wheel showed 140.5*.

Halfway between 59 & 140.5 is 99.75*, this is my intake lobe centerline measurement. Hamilton calls for a 99* intake centerline so the cam is ever so slightly retarded 0.75 *. After the head is installed, I'll be able to check the piston to valve clearance which should be sufficient with the cam installed within 3/4 of a degree of the intake centerline.

 

[Big Blue24]

I also wasted some time working on the oil pump for this motor, here is the old stock oil pump:

New part number 24v/12v oil pump:

And here is an 8.3L Cummins C-series oil pump Melling M-350:

From left to right: 8.3, New 5.9, Old 5.9

As you can see, the 8.3 pump is taller than the stock 5.9 pump:

Backside of the 8.3L on left vs 5.9L on right:

Without the covers, believe it or not, they are within a couple thousandths of an inch of the same measurement on the center rotor. 95% of the oil pump displacement difference comes from the extra depth of the 8.3L pump. The 8.3L pump will bolt-up, however, the added depth means the pump rotor bottoms out against the block recess about .200" before the bolted cover snugs up to the block. It will work but the idler gear is dangerously close to the edge of the crank gear. The idler gear also has (1) more tooth so the 8.3L pump is slightly overdriven compared to the stock 5.9 pump. The 8.3 pump gears could be easily milled down to fit since the backing plate is easily removed, however, then you lose 95% of the displacement advantage so the only real benefit at that point is the overdriven (1 tooth oversized idler gear). I decided to go with a new stock 24v/12v pump and will perform other modifications to the rockers to conserve oil volume.

 

[estrada5.9]

You need to get a junker drag truck book published.

Excellent read sir thanks.

 

[super duty04]

Awesome thread! Thanks blue for all the pictures and information. I am in the process of doing a similar build for a local 2.6 puller. Keep up the awesome work.

 

[Big Blue24]

I installed the head using the old stock compressed head gasket to check piston to valve clearances.

It's starting to look like a motor:

To go along with the upgraded valve train, I located a cheap used set of upgraded push rods. These push rods are just a touch shorter than stock and only average 3-4 grams heavier than the stockers.

They have a one-piece design vs. the stock one that's made up of 3 welded together pieces:

Upgraded pushrod weight:

Stock pushrod weight:

 

[YOUNG GUNS15]

hey your garage isnt nearly as clutttered anymore!

Think you'll having it going for mopars on the strip in april?

 

[Got Smoke?]

:drool1: :rockwoot:

 

[Big Blue24]

Oil Pressure Modifications


These mods can be performed with the motor installed or out on the engine stand.

First you need to remove the 3/4" plug/bolt that covers up the oil pressure regulator assembly:

Here's the backside showing the bore where the regulator shuttle valve and spring reside:

According to the Factory Service Manual, the spring has a free height of roughly 2.6" and a compressed installed height of 1.6", meaning the spring is compressed 1" to create the specified load of 28.4 lbs. The regulator valve with a 28.4 lb spring load will move when 65 psi oil pressure pushes on the bottom side.

To increase oil pressure, we need to increase the spring pressure. I found a smaller diameter spring in my old transmission parts box that fits inside the larger spring, I then rigged up a scale on my drill press table to measure the load this spring creates when compressed to a height of 1.6". This spring created a load of roughly 11 lbs with will increase the overall spring load to 28.4 + 11 = 39.4 lbs. This is an increase of 38.7% which will increase oil pressure to just a touch over 90 psi.

Pictured is the stock spring in the middle, new inner spring on the left, and regulator valve on the right:

Next I needed to modify the oil pressure bypass valve. According to the FSM, this valve opens when pressure differential across the oil filter is 25 psi or greater. Due to the fact that I'm winding this motor up much higher RPM than originally designed, and I've increased the pressure, there is a high likelyhood that there could be greater than 25psi differential which will cause unfiltered oil to bypass the oil filter and directly run to the oil/lube system for the motor.

Bypass removed:

Spring specifications are not provided for the bypass valve so I threw it on my scale/drill press setup and came up with roughly 2.5 lbs of force are required to open the bypass. I added a small pen spring to the underside of the bypass valve and rechecked the opening pressure and found it to be 3.5 lbs. This 40% increase in spring pressure will raise the bypass pressure differential to roughly 35 psi. Hopefully if I continue to run quality oil filters, it won't create enough pressure differential to ever need to open but it does still have original functionality, just at an upgraded level.

In order to keep the small spring aligned, I used a 1/8" drill bit to create a pocket/seat in the bottom of the bypass valve's plastic/poly/nylon plunger, once installed, the spring is trapped in the bottom of the aluminum bore and captured in the bypass valve recessed pocket. Simple, functional, and reliable.

 

[Big Blue24]

Checking Valve to Piston Clearance

To check piston to valve clearance, I had to fully assemble the head and torqued it down on the old used standard thickness gasket. After setting valve lash at .010" intake and .020" exhaust, I positioned my dial indicator over the exhaust valve retainer on #1 cylinder. Then using my degree wheel with wire pointer to verify engine rotation, I turned the motor using the rear crank bolt circle to 15* before top dead center. Next the dial indicator was zeroed, then the valve was adjusted downward with the lash adjustment bolt until it contacted the piston. I noted the measurement (80-120 thousandths cant recall exactly) then adjusted the valve back to it's starting point (where the indicator shows zero). Next the motor was rotated to 10* before TDC and the clearance was checked again.

The whole process was repeated for the intake valve starting at 5* before TDC and working out till 15* after TDC.

On my particular motor & cam setup, the intake valves were tightest at 5-6* after TDC and the exhaust valves were tightest around 7-8* before TDC. The tightest intake measurement was too tight for comfort at .030", and the tightest exhaust measurement was a little tight at .038". It was close enough that I decided to check all 6 cylinders and ended up with a range of tightness between .029" to .032" intakes and .037" to .040" exhausts. To gain clearance, the final assembly will utilize a .010" over head gasket (which was the original plan from day one).

For those wondering, piston protrusion on this motor is sitting right at .016" to .017", the head has never been milled, the valve seats are stock, the valves are used/resurfaced but I didn't check valve recession (assumed to be still near factory specification), the intake center line as measured at the #1 intake valve retainer at .010" either side of the lobe peak is 98.75*. This is an older/tighter 188-220 cam with the narrower lobe separation angle.

Dial indicator positioned over #1 exhaust valve retainer:

 

[Big Blue24]

hey your garage isnt nearly as clutttered anymore!

Think you'll having it going for mopars on the strip in april?

I plan to get it running ASAP, drag strip in Vegas reopens Friday night January 24th for street legal midnight mayhem racing. It's a lofty goal, but achievable......

 

[turfin8705]

Hey big blue a little word of advice. When you add that extra spring to increase oil pressure make sure to install the springs so that they are coiled in opposite directions. If you install them both coiled the same way their will be a good chance it'll bind.

 

[dalenw]

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