95' Junker Drag Truck

With the fuel leak fixed you should be running close to 120mph on the big end.
 
straight 6 roar said:
I assume you don't have a fuel pressure gauge? What's your best 60 ft time? If you could get it down to a 1.9 it would slash those ETs.
Click to expand...

My best 60' to date is 1.90

Back in March, with less power but much better track prep down at Speedworld drag strip in Wittmann, AZ at the NHRDA event, I ran a 7.96 1/8th at 91 MPH.

The biggest difference in ET came from the 60' to 330' section of the track although the much better 60' really helped as well. The main reason I couldn't run quicker than 12.3's at that event was converter slip in 3rd and 4th gear with the reman single disk converter. I now have a triple disk converter so the back half of the track has become equally quick and MPH has increased after every power enhancement.

Friday Sept 2nd is the next street-legal race night in Las Vegas. There is a semi-pro test session before so track prep should be better than it was at RMR at the NADM event.



As far as a fuel pressure gauge, I do not run one when I race, but I do have one for trouble-shooting/testing.

With the leaking line, pressure bounces from 25-30 psi at idle, jumps up to 35 psi with my secondary lift pump (it normally idles around 45 psi and sits at 65 psi with the secondary lift pump turned on).

On the road, it fuels fine with the lower pressure till about 2800 rpm, from there on up there is noticeable power decline and it won't rev past 3500 in gear (2nd gear) with the leak.

In short, the 160 pump needs 40+ psi to fuel correctly above 2800 rpm and it seems to make the most power with 50+ psi.

Without the leak, it pulls hard to 4200+ rpm, I just stopped there because that's as high as I need it to fuel.
 
Just spent my Sunday afternoon reading all 85 pages. Can't wait to get back to work so I can finish up my pos

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Racked Pump Barrels

Recently, I performed another free modification to the injection pump of the Junker Drag Truck. A common performance upgrade is to get the pump "benched." To do this, typically you remove the injection pump and send it to a pump shop where they will max out the barrels and then turn them back just enough to get them all balanced with eachother. If you max the pump at home, you likely won't have an easy way to balance the pump. In my maximum effort, minimum budget build, I decided to forgo the expense of a pump shop and live with the slightly out-of-balance pump. (I figure the stock pump with 240K miles probably has differential wear from one barrel to the next so it was probably way out of balance to begin with).

First I removed the intake elbow, large clamp with 8mm nuts that holds all 6 injector lines together, and loosened all 6 injector lines at the pump 19mm or 3/4" wrench.

Rack01.jpg


Here is a close-up picture of the barrels in the stock location:

Rack02.jpg


Next I loosened the twelve bolts that secure each of the 6 barrels (two bolts per barrel 14 or 15mm, can't remember now). You have to completely loosen some of the injection lines so that they can be flexed over just a little to get enough space for your socket and extension.

Rack03.jpg



I then used a long 3/8" extension as a drift/punch and using a hammer, I tapped each barrel in the clockwise direction, they only move about 1/8" till they bottom out. The barrels make a dull sound when they are moving; when they bottom out, they make a sharper pinging noise.

Rack04.jpg



In this picture the top barrel is racked, the bottom one is not. The dark area on the top barrel is the amount it moved from factory stock location to fully racked.

Rack05.jpg


This is a picture of me tightening the fully racked barrels, the darker area is where the barrels were in the factory stock location. As you can clearly see, the side of the barrel closest to the engine rotates backward toward the driver's compartment, the side of the barrel away from the engine rotates forward toward the front of the vehicle, which is clockwise when looking at the pump from above.

Rack06.jpg




Now for the results...

Previously, I had the idle set pretty high, 1100 rpm, with 5.5K governor springs. After racking the barrels, idle jumped up to 1600 rpm. To fix this, I adjusted the idle screw all the way down and then loosened the governor springs two clicks or 180* on each side. This dropped the idle to 1000 rpm in neutral, which is where I like it on this truck, about 900 rpm in gear.

On my first test drive there were two things I noticed:

1. The truck actually idles silky smooth, it wasn't bad before, but it's much smoother now.
2. The mid-range and topend fueling is smoother and feels more predictable.

There is definitely more fueling potential with the racked barrels, and power output increased significantly. I'd have to guess total power increased anywhere from 50-80 HP. I have not made a full pass at the track yet to see how much the trap speed has changed but I plan to make some runs at the track this weekend.
 
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I can't believe that's all there is to racking the barrels. Seems too simple.

Thanks for sharing will.
 
Wow now that I see this I realize how obvious this should be with a little knowledge about how these work. Good post blue.
 
SCHOOL BUS said:
now get some real slicks...
Click to expand...

I'd love to try a set of slicks, just can't afford them. If Mickey Thompson, M&H, or Hoosier wanted to sponsor a set LOL I'd run them.(not sure anyone would want their name associated with The Junker Drag Truck) I've really been looking closely at drag radials, as big as I can get for a 15" rim. Seems like 315/60/15 is the tallest and widest available - 30" tall, 11.9" wide.

Tomorrow night is street legal night so I'll have to run my 285/75/16 Mud Terrain Wrangler MTR's. If I can cut a 2.0 60' time, I can run 11.98 with about 123 MPH trap speed. That trap speed would take 95 RWHP more than my previous best 117 MPH. I don't think the racked barrels added 95 RWHP, so unless I get a sub 2.0 60' time, I don't anticipate seeing an 11 second 1/4 mile.
 
If you were closer Id see to it to get you a set of rubber for the rear of that truck. Im around soo many racers every weekend and deal with tires so often that getting a good used set is very common.

It was good to meet you at the RMR event a couple weekends ago, good luck to you and your project racer.

Ryan Tucker
 
how did this effect your fuel pressure? if it is still holding strong i'm definatly getting a pro comp pump and racking the barrels
 
I have heard a few "horror" stories about rackin them without a bench, but I've also hear 4-5 people on here and CF that have done this with great results. I might have to do this!
 
i have about 15,000 miles on my unbenched pump. I said i was going to get it benched but that never happened lol Still idles and runs great
 
My buddies truck got a lil rough on the idle when we did his. still ran pretty good though
 
This settles it, I'm putting in my 5k's and racking the barrels this weekend!!
 
I picked up a "junker" 93 RCLB 2wd....I think we should see who can go faster....I'm wanting to make a VE go fast....

Chris :poke:
 
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