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71K5 - BP71K5's Just for fun build

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Something's definitely odd with my fuel pressure gauge. This morning when I started it to get it up to temp for a test run, the fuel was at 16psi, then dropped to 14psi by the time I got back from a test drive. Going to have to figure out if that's real or not.
 
Update 9/23/2017

Got my new injector tree and fuel pressure regulator.
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New one on the left, old one on the right.


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The new one doesn't have a regulator in it, so an external one is needed. It's a fairly nice piece of billet aluminum with a simple barb fitting for the fuel inlet.


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Theory is the smaller injectors let it breathe better. The injectors can take a lot more fuel pressure than the tbi injectors. Fairly simple swap.


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Wired up.
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Put the regulator inside the frame rail. Pressure is at 60psi at the moment, but it's running lean again and the fuel tables are about maxed out so I think it needs more pressure. Injectors can take 70psi, so I'll probably try 65 and see where it ends up.
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Then in a frustrating turn of events after a few hours of testing, I discovered a coolant puddle coming from my radiator. :angry1:
 
i was about to hit the like button until I read the last sentence, then I thought you'd take that the wrong way...

So, a 95% like, then a dislike for the rad leak. Final answer.

:D

Edit: How do you feel about the FPR location? I have mine up high on my firewall, nice and safe, easy to read etc. I'm a little concerned yours may be in a vulnerable spot, at least for the gauge?
 
tRustyK5 said:
i was about to hit the like button until I read the last sentence, then I thought you'd take that the wrong way...

So, a 95% like, then a dislike for the rad leak. Final answer.

:D

Edit: How do you feel about the FPR location? I have mine up high on my firewall, nice and safe, easy to read etc. I'm a little concerned yours may be in a vulnerable spot, at least for the gauge?
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Once the tune is about done, I'll remove the gauge and plug the hole. Location is not my favorite, but is the best compromise I can find for the moment. I may build a small shield for it once the gauge is off to protect it from broken belts, etc.

That said, the tune is getting closer. This thing is fun to drive with the pedal down. Has no trouble getting up and moving even from a low gear and the speed can kinda get away from me quick without me noticing since the exhaust is relatively quiet and the rpm isn't as high to get a "comfortable" acceleration. Still have to finish the shifters, trans tunnel, etc but aside from the radiator I'm happy so far.

Not sure what to do about the radiator. Probably see if someone can fix it and tell me why my truck keeps killing them. That or I might drive over to Tesla and see if they have any motors that don't need coolant.
 
Update 10/4/2017

Not sure what's going on with the radiator. It started leaking worse from the lower hose, I tightened the hose clamp and it stopped, started leaking from the upper hose, tightened that and it stopped again. Now it's not leaking at all. I don't trust it though.

During tuning, I installed my chip backwards and appear to have fried it. Got a few more on order from moates.

While I'm waiting, finishing up the transfer case shifters. The 205 was easy enough to modify the bracket to fit the same as before. The tricky part is the magnum since the shift mechanism is in a different area on top of the magnum rather than down by the 205 shifters.

Stephan's suggestion was top weld a heim pivot on the shifter above the pivot rather than below like it was before. That would work pretty well if I had more room under my trans tunnel. But with the tunnel in place, the amount of movement I get at the magnum shifter requires a lot of shifter movement up top where the handle is. So much that it would interfere with the transmission shifter even more than it does in the picture below.

So I decided on an alternative that reduces how much interference there is up top but is a little more complicated below.

IMG_4896.JPG

It's a fairly simple pivot linkage. The orange part pivots in the center and take the shifter pull on the bottom and transfers the force up to the top heim which is connected to the magnum. The pivot distance on top is larger than the bottom. This lets the heim on top move farther relative to the heim below. I lose a bit of leverage this way, but the magnum shifts so easy it's not an issue.

Few more pictures
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Here's the interference with the trans shifter when in ultra-low gear. I plan to make a new shifter with a bend forward so it's about vertical when in second gear. That way the interference shown will go away.

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This is highway driving mode. The trans shifter is already a little farther back than needed so bending it forward should be fine.


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Glad you posted those pictures. I've been wondering how the shifters work with the Magnum. Did you start with an ORD triple stick? I'm almost tempted not to twin stick the NP205 but then I'm wondering if that would make it harder to get the Magnum setup. Although I suppose I could use a cable shifter on the Magnum.
 
mrk5 said:
Glad you posted those pictures. I've been wondering how the shifters work with the Magnum. Did you start with an ORD triple stick?
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Yes. i think they came with a nv4500 mount (maybe similar to a 203 mount), but I cut it up to fit my situation so there's not much of the original left.

The lever on the magnum can be flipped around. In high gear (as shipped) it points toward the drivers side and forward. I flipped mine around so it pointed to the passenger side rear in high gear. The shifters looked easier to set up that way and the bonus was that all my shifters line up out of the way on the freeway rather than having one pushed forward and the rest back. Although front wheels are normally in neutral on the freeway.
 
10/6/2017

Tune is coming along, but something new has developed when I hit the brakes while turning a little sharp. I'd describe is as death wobble. It wobbled my emulator right out of the ecm and killed the engine the first time it happened. Scared me pretty good. I've never had a single instance of it before so not sure what changed other than the motor mount and crossmember. Maybe the frame is not as rigid as before? I guess I should check all the bearings and joints.
 
Update 11/2/2017

Turns out my death wobble happens when hitting some kind of pothole or bump, not just braking. I see some grease leaking out of the passenger side front tire so maybe something's going on there.

But, I've been tuning some more, patched and painted the trans cover, and made a new shift lever. Decided it would be easier to bend the trans shifter around the magnum shifter since I already wasn't happy with the straight shifter placement. Second gear always interfered with my drink in the cup holder. :rotfl:

Some 5/8" rod, heat, bending and welding. I got a metric tap for the large threads on the shifter and tapped a steel tube spacer from mcmaster Carr. M16-1.5mm

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Update 11/26/2017

ORD got me some kingpin springs and bushings pretty quick so I replaced those and pumped em full of grease in an attempt to fix my death wobble. A quick test drive over a known deathwobble inducing pothole indicates the problem is fixed.

But comparing my new spring lengths to the old, there's not much difference. I do find some wear on the bushings, but they aren't totally trashed.

New spring length for future reference is 2.25"IMG_5123.JPG

Old springs are maybe 1/16" shorter
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Old bushings. You can see the cupped areas surrounded by black grease on the left bushing. I cleaned the right one to try and measure how much was worn off, but it was too difficult to measure.
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Also did some fine tuning of the timing curve and was able to really wake up the motor. Very healthy amount of torque and very unhealthy amount of gasoline used per mile because it's so fun. :D
 
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Update 12/23/2017 Merry Christmas

Didn't like running without a knock sensor, so found a reasonable spot under where the fuel pump would go. Seems to work ok. I get 2-3 knock counts in an hour of driving and always on a shift. I think even those are just mechanical noise.

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I also keep chasing fuel leaks and coolant leaks. The fuel line from the frame up the motor was the old stainless hard line with hoses clamped to the end. I just couldn't get those to reliably seal even with double clamps so I bent up a spare 2' section of stainless tube and installed a couple of these fragola fittings that adapt tube to -6 fittings. Has been working well so far.
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bp71k5 said:
Update 12/23/2017 Merry Christmas

Didn't like running without a knock sensor, so found a reasonable spot under where the fuel pump would go. Seems to work ok. I get 2-3 knock counts in an hour of driving and always on a shift. I think even those are just mechanical noise.

View attachment 253371

I also keep chasing fuel leaks and coolant leaks. The fuel line from the frame up the motor was the old stainless hard line with hoses clamped to the end. I just couldn't get those to reliably seal even with double clamps so I bent up a spare 2' section of stainless tube and installed a couple of these fragola fittings that adapt tube to -6 fittings. Has been working well so far.
View attachment 253372 View attachment 253373
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I wish my big block was half as nice!
 
Epic build, love the direction you have taken this truck. I've read bits and pieces of this thread over the years, just went through the entire thread in order over the course of the day when I had a few minutes here and there. One of the nicest K5's around.
 
LNielson said:
Epic build, love the direction you have taken this truck. I've read bits and pieces of this thread over the years, just went through the entire thread in order over the course of the day when I had a few minutes here and there. One of the nicest K5's around.
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Thanks! It's coming full circle a bit here. Working on getting the radio working again. I've also discovered how useful sunvisors are in this thing so those are on the list too.
 
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