Mexacali Express ('72 K10/LQ4/TH350 Retrofit)

[jpstaub]

At zero dark thirty a ring tone pierced the quiet of the night and jolted me awake.

"Damnit! I need a pack mule. Something with guts that never looks for glory. My shipments keep getting clipped and I am not a charitable man. The base of ops is a ratty '72 K10. Do it right or don't do it at all." Click.

I wish that's how this whole thing started but it wasn't although I'm already fond of the intro so I may carry on the white lie as long as nobody gets hurt. The truth is, my girlfriend's boss liked the job I did on my '72 C10 so much he wanted the same done with his '72 K10. The only real problem was that I was starting with this:

In the end the boss wanted something that looks like this:



I'm getting a community repair/repurpose/fabrication shop started (see example here) so I signed on to do the mechanical work for the project.

After $30k and 700 hours of labor Mexacali Express looks like this:



Had the owner done all the work the project would have cost about $15k which is still a large chunk of money to blow. The intent here is not to consider why people spend time/money the way they do. Instead I'd like to offer solutions to technical problems I ran into during the build. This is about giving back to the community who's assisted me, many times unknowingly, with problems I've encountered along my path to resto-rod glory.

My goal is to give plenty of documentation and relatively in-depth explanation to the unique hurdles encountered on the project. I'm going to leave beginner stuff alone since there's plenty of material out there and as much as I like technical writing, time is limited. If additional explanation is desired to fill in gaps that I'm leaving because I've become too familiar with this stuff let me know.

Cheers,
Jake

[jpstaub]

Click here for the Mexacli Express Build Sheet. The build sheet contains information about parts, prices, and suppliers that may come in handy when sorting through typical problems: what hoses to use, what intake to use, who makes an exhaust kit, etc. A time sheet is also included which ought to give the average guy an idea about how long certain upgrades may take.

[jpstaub]

A lot of research was done prior to the build to determine if going 4L60E or 4L80E was practical. To me it seemed like 67-72 4x4 guys going the computer controlled transmission route were fighting pretty hard to make it happen. My previous project, C10 with LQ4, used a 700R4 so I already knew how to strip the transmission wiring out of the harness. With the K10 a lot of other considerations crept in: front drive shaft to transmission pan clearance, transmission to transfer case mating, transmission tail shaft swapping, etc. Since the Mexacali Express will only be driven about 5k miles/year overdrive just didn't seem like it was going to be worth the trouble and money.

Note: If your intent is to use a non-computer controlled transmission in front of an LSX engine LQ4's out of GM vans is a nice way to go. The vans retained cable actuated throttle bodies until '07 according to reports which makes the swap less painful when dealing with cable actuated transmissions like the TH350 and 700R4. Later model years also means you're more likely to find a lower mile engine to use for your build.

Click here for one of my favorite places to research and find used auto parts quickly.

[jpstaub]

This K10 came with the engine set in the rear most position from the factory. I've seen at least one article on a C10 LSX swap where the stock engine was also in the rear most position. There are likely people on the forum that know why GM put the engines in the rear most position. I do not.

Bottom line: An LQ4 will fit even if your engine was originally mounted in the rear most position. There's no need to move the transmission/transfer case forward.

Required items:
1. Remove rear most ignition coil mounting bracket boss from passenger side valve cover.

2. Remove corresponding mount point from ignition coil mounting bracket.

3. If using stock engine temperature gage use: VDO Temperature Sender 300 Degree M12x1.5 (part no. VDO-323092). The temperature curve is slightly different than stock but the gage will display correctly and still indicate to the operator the temperature status of the engine.

4. Massage passenger side firewall as required.

5. Massage driver side firewall at throttle pedal mount boss location as required.

6. Add spacers to throttle pedal mount bolts to keep bolts from protruding past bosses.

[jpstaub]

There are a few different ways to go with the cross member.

1. Modify existing cross member.

2. Use aftermarket cross member that's engineered for the application.

3. Fabricate your own cross member based on good design/engineering practice.

4. Cobble parts together that weren't made for the job and won't do the job in the long term.

I chose #2 but saw some ideas for #4 that had me shaking my head. If I had more fabrication practice and equipment I would have given #1 a go.

The cross member came from Pacific Fabrication. It looks like this:



There are a few important things to know about this cross member in general:

1. You will end up fabricating a driver's side brake line to clear the cross member until Pacific Fabrication changes the driver's side design to match the passenger side (see notch on left side in photo).

2. You may end up modifying the brackets that mount to the frame to make them work for you without interfering with other items like brake lines on the driver's side frame rail and front suspension bump stops on both sides.

3. A lift was required to make this cross member work. This "small" item doesn't get enough emphasis for my taste. It made the build more expensive and delayed completion of the project. A 2.5" front lift gave approximately 3" of clearance between the front differential housing and the cross member. 4.5" Energy Suspension universal bump stops were used on the front to prevent differential housing to cross member contact.

For an LQ4/TH350 install with the stock engine starting in the rear most position you should know this about the Pacific Fabrication cross member:

1. Custom engine mounting plates will be required. The front face of the rear mount ear should be place approximately 14.75" from the face of the transmission bellhousing surface. A picture of the brackets appears below:



Passenger side mounted to LQ4:



Driver's side mounted to LQ4:



Standby for a file that will allow fabrication of these brackets. If you don't have the ability to cut 0.25" plate steel not to fear. Places like Big Blue Saw can hook you up like they did me. You can then weld the parts or take them to a local lead pipe swinging welder for assembly.

[jpstaub]

LQ4's from vans typically come with power steering pumps that have remote reservoirs. If you want to keep everything together you can substitute a late model truck pump and reservoir as a one-for-one swap.

If you have an original power steering pump on hand pull out the power steering flow valve before discarding the pump. You can use this valve in the late model power steering pump so stock-type power steering pressure hoses fit without an o'ring adapter.

If you had to use the custom engine mount brackets mentioned in a previous post you really do not want to use an o'ring adapter as the clearance between the power steering pump and engine mount bracket ear is minimal. See below:



Stock-type power steering lines were rebent to connect the power steering pump to the power steering box. Universal lines may be a better option. I had new stock-type lines on hand so I made them work.

[cobra_4]

Great info! Planning on going LS in my project truck!

[71blksuper4x4]

Hey your boss has good taste in trucks. That's a pic my blue and white 71'. Good information you are putting up. Trevor

[Low Elco]

Hopping on this train- lots of good info here! Bookmarked! You oughta PM KRUE and USMCchevy to add this to the FAQ stickies!

[67cheby]

nicely done, very informative thread !

[Bomp]

Note pad...check
bookmarked.check
subscribed....check

[jpstaub]

Click here to download a copy of the CAD file needed to make the custom engine brackets for the Pacific Fabrication cross member referenced in a previous post.

Once you download the file upload the file at Big Blue Saw on any other cutting service you'd like. Big Blue Saw is really easy to deal with but there are other services out there including guys with CNC plasma cutters in their garages. Big Blue Saw will display what the cut parts will look like. They should closely match the picture below.



Choose your material. 0.25" steel is recommended based on the thickness of the original parts. In my opinion cold or hot doesn't really matter for this application. To each his own however.

If guys want to crank out 10,000 sets so be it. All I ask is that any modifications to the original file be posted in turn so that others out here can benefit. A $5 donation to the beer kitty is welcome. Shoot me a PM for contact details.

Disclaimer: This file is offered without warranty or guarantee of suitability. If you assemble the parts that means you're taking full responsibility for how well or poorly the assembly operates. If you can't weld find someone who can. The part finish from CNC waterjet cutting is so good that assembly adds very little to the overall cost.

[jpstaub]

For those of you who can check the oil level in the engine every once in a while there's no need for the oil level sensor as originally equipped. Discount Hydraulic Hose has what you need. Use part no. 9029-20x1.5. The installed plug is shown below.



For those that want to use something else as long as it's 20mm x 1.5pitch it'll work.

[jpstaub]

For those with the factory oil pressure indicator, Auto Meter Part No. 2268 will hook you up with an 1/8" NPT outlet which happens to be the thread size of the stock oil pressure line setup. The installed fitting is shown below.



For the oil light guys, the thread size of Part No. 2268 is 16mm x 1.5pitch. I bet VDO makes a pressure switch that can be used with the stock '72 wiring harness. A little speculation on my part but worth the effort to chase it down I think.

[eagleuh1]

One of mthe best, most complete writeups I've ever seen. Thanks for taking the time and effort. Especially on the file for te motor mounts. Kudo's. Jim

[Low Elco]

Dang, this is a lot of good info! Almost makes me want to dive in!

[jpstaub]

Safety is a topic that doesn't get a lot of play in the performance world at times. I don't mind. I like to be as much of a hazard as the next guy. But I do recognize that passengers may expect not be turned into a block of carbon as a result of high pressure fuel spray after a crash.

In the Vortec Retrofit Wiring document included in a previous post you'll see a "CRASH SWITCH" in the upper right hand corner. It's wired such that power is removed from the ECU in the event of a crash. By removing power from the ECU not only do the fuel pumps stop pumping but the ECU can no longer control spark or fuel injection disabling the engine. If you talk to accident investigators one item they will mention is that when people/police first arrive on the scene of a bad head-on crash the engine of the vehicle will be screaming because the driver's foot is jammed down on the accelerator pedal. Not to be morose, but with all the idiots out there texting instead of driving it's a good idea to think ahead because they're not.

Ford did us a solid by incorporating inertial crash switches in tens if not hundreds of thousands of vehicles. If you go to Ebay and type in "inertial crash switch" you're bond to have a selection to choose from. Usually they'll come with a wire pigtail which will save you some money and time sourcing a connector. A typical setup is shown below. If you'd rather have a new switch use part no. 1S3906. Connectors are commonly available.



So now that you're a little scared for your life how/where to install the switch? An image below covers the basics. Installing the switch upright will allow the metal ball in the switch to drop in a crash breaking the circuit. I like to put the switch in the cab on the throttle pedal bracket which keeps it out of the weather, out of the way, but accessible. It also allows me to run a lead from the little used "Glove Box & Spot LT" fuse on the stock fuse panel for power. Shown below is a Ford installation but it gets the idea across.



For guys that like to know how things work the image below shows how the switch is operated. If you'd like to test it out prior to installation smack the switch against your palm to activate the inertial release. Test with multimeter; circuit should be open. Reset the switch and test again; circuit should be closed.

[jpstaub]

For Key Power I use the original ignition wire. It's on when the key is on which is how we want Relays 1 and 2 activated. With the key off Relays 1 and 2 are deactivated and battery power is preserved. For a visual depiction see the retrofit wiring diagram in a previous post.

[jpstaub]

Type I circuit breakers are used in place of fuses for the fuel pumps and the electric fan. What gives?

A type I circuit breaker automatically resets power after it's amperage rating is exceeded. This is a good feature when using motor driven electrical devices. Motor driven electrical devices are, in general, known as inductive loads. This means when the device is first powered up it takes a certain period of time for the magnetic field and therefore the resistance in the load to build up to normal operating levels. Therefore, when power is first applied there is a spike in current well above the steady state rated operating current. Whhhhhat?

Believe me, I learned all that crap above the hard way. That super stout Spal electric fan I reference in an earlier post kept blowing 30A fuses. It would turn on once or twice then nothing (makes for sweaty palms and nervous glances at the temp gage when waiting at red lights which I always manage to hit). The reason was the spike in the current when the fan first turned on. A handful of spikes would melt the fuse. What about a fuse of higher rating? The mini fuses that make the Cooper Bussman RTMR panel so sexy have a max rating of...you guessed it, 30A.

In a roundabout way I finally stumbled on a reference explaining that OEMs use Type I circuit breakers whenever they're driving inductive loads: power windows, fuel pumps, electric fans, etc. Now you know.

The 30A Type I circuit breakers aren't all that common. Use part no. CB211-30 to get the treasure hunt started. Drillspot is where I got mine.

[Bomp]

Thanks for all the helpful info.
I have it bookmarked for when I get to that point in the build.
Keeping notes.

[jpstaub]

Stock harnesses come with two grounding ring terminals. Once all the extraneous stuff is removed from the harness there's no reason to keep both terminals. Merge all the ground wires together on one of the grounding rings and remove the other for a cleaner installation.

As far as installation is concerned, GM uses bellhousing stud bolts (part no. 15724226) to mount the transmission. Choose a place that looks good to you, throw a bellhousing stud bolt in and bolt your ring terminal on (they're perfectly sized for the stud). See below for a picture of the fastener.

[jpstaub]

Originally Posted by jpstaub

In the Vortec Retrofit Wiring document included in a previous post you'll see a "CRASH SWITCH" in the upper right hand corner.

"Upper right hand corner," should read "upper left hand corner."

[jpstaub]

Even with Delphi's catalog linked in a post above there are a lot of choices to make. Some guidance follows:

1. GT series connectors are the easiest to work with when it comes time to take them apart. Say you put a terminal in the wrong position. With GT series connectors you can generally get the terminal out without much in the way of terminal removal tools other than a jeweler's screwdriver (not that this should solidify a decision since removal tools are pretty cheap). This is due to the tangless design of the terminals for this series.

2. Metri-Pack series connectors are harder to take apart. However, they are the choice for high amperage circuits. They take a terminal removal tool that's relatively common. The terminals are in the auto parts store supply chain. So, if you don't order enough terminals chances are fair that you'll be able to get more terminals without having to wait for a shipment. The same probably can't be said for GT series stuff.

3. Both style terminals require a crimping tool. Item #533 at Waytek is the lowest cost way to go. I've gotten good service out of my tool although if I were doing a lot of harnesses I'd upgrade.

4. Item #422 at Watyek will give you the ability to remove Metri-Pack terminals. I've also used it to work on Series 56 terminals. This one is well worth the money even if you don't play with wiring much. The first time you use it it'll pay for itself.

As far as connectors go relative to the retrofit wiring diagram in a previous post:

Connector A - This one mounts under the dash out of the weather so a sealed connector isn't necessary. Something in a 150 series will do the trick. Up to you how many cavities (the number of connections) you'd like. I used a six cavity connector for the ability to add an ECU generated vehicle speed signal and RPM signal at a future date. Four cavity is fine if you will never take that option.

Connectors B&C - These need to be weather sealed since they're located under the truck. 150 series 2 cavity is enough to get the job done.

Connector D - You can get away with a 2 cavity Metri-Pack 280 series that has a max continuous 30A rating. I've been using a 2 cavity Metri-Pack 480 series which has a max continuous 42A rating for added security. Just make sure the connector is weather sealed since it'll be in the engine compartment.

Connector E - A 150 series 2 cavity unsealed. You can use something even lighter weight if you'd like since both connections are moving small currents.

Connector F - A 150 series 3 cavity unsealed. Again, substituting something lighter would be fine based on the very small currents involved.

Finally, a quick note about ordering connector components. Always order more terminals than you'll need. I go about 20% more to cover my errors as well as errors on the part of the supplier. It sucks to be near the end on a wiring job and run out of supplies. Chances are you'll run out of the item that's impossible to find on the local market. By the way, unless you're lucky, buying anything connector related on the local market costs 5 to 10 times what it does when ordered from Mouser, Digi-Key, Watek, etc.

[jpstaub]

It may be tempting to leave out the OBDII connector but you really want it. It allows you to pull diagnostic information as well as to turn your motor into a fire breathing monster with the appropriate tuning. It's the interface with the brain that's running the show.

You can find all the information regarding part numbers for the connector in the Delphi Global Connector Catalog on page 2.18. Just be careful about the Tangless part. You've got to use Tangless terminals with the connector.

I put the OBDII connector on the metal plate that's under the steering column. Locating the connector on the end that's nearest the driver's feet makes for a clean installation that no one will see.

For power find the pink wire in the dash instrument panel wiring harness and tap into that (it should go to the instrument panel printed circuit board connector). Place terminal in cavity #16 (the connector is labeled with tiny numbers; you'll probably need good light to see them).

For ground, look for the ground connection that's behind the dash (probably to the right of the hole for the instrument panel). It's a little metal clip that clamps to the dash panel. Or, you can use a multi-meter to test the printed circuit board connector terminals for ground. Ground a multi-meter probe on the dash metal then go around the horn on the printed circuit board connector looking for continuity. The wire of interest should be black (be careful; there's another black wire on the connector that's used for the charge gage trucks; it's natural state is +12V). Tap into the ground wire. Place terminals in cavities 4 and 5.

Throw a terminal wired to computer terminal C1-58 into cavity 2 and you've got OBDII diagnostic/programming capability.

[67cheby]

i think i am going to be getting alot of tips from your thread very soon ! I am going to be doing the same thing in my wifes Blazer, keep up all of the GREAT INFORMATION !