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.

[jpstaub]

Front side driver's side cross member mounting showing fabricated brake line and top bracket mounting hole lowered 0.75" to avoid brake lines on other side of frame:



Back side driver's side cross member mounting showing fabricated brake line and top bracket mounting hole lowered 0.75" to avoid brake lines on other side of frame:



Front side of passenger's side cross member mounting. Slots in bracket that bolts to cross member had to be lengthened by drilling and filing:



Back side of passenger's side cross member mounting. Slots in bracket that bolts to cross member had to be lengthened by drilling and filing:

[jpstaub]

Head-on picture of the mighty LQ4 installed. Note the water pump has been modified to accept the coolant from the throttle body heater line. The fitting is straight barbed brass 1/8"NPT.



Picture of driver's side. Note how far back the engine sits in the frame. This generates problems with exhaust manifold clearance. That problems was addressed by using C5 Corvette exhaust manifolds with heat shields removed. There's also very little clearance to run a hose for the power brake booster. That problem was tackled by sourcing a 180 degree formed 1/2" hose from the parts store (part no. 5199956).



Picture of passenger's side. You can make out the small arm that's been spot welded to the throttle body actuator for TH350 kickdown cable attachment. More on that later.



Picture of bottom of engine. There's a lot of side clearance between the cross member and the oil pan. With a closer fitting design the need for a 2.5" suspension lift might be eliminated.

[jpstaub]

There isn't a lot of information out there on solving the TH350 kickdown problem. That's likely the result of relatively few LSX swaps going backwards by keeping the TH350 in the game. But, if you're on a budget or want to put a lot of power through a transmission without blowing it up or don't need overdrive or any other reason why you want to remain a cave man then maybe this will help.

Problemo numero uno:
Attaching the kickdown cable to the throttle body in the first place. For me the solution came by way of Street & Performance and their Add-on Detent Bracket for 350/700R4 Transmissions (sorry, Street & Performance doesn't give a part number). $37.95 is a raping for what is essentially a flat piece of metal with a grand total of two holes. No. It's not made of solid gold. On top of that, you've got to weld the thing to the throttle body. Next time I'll make my own. Check out the picture below to see what I'm talking about (top cable is throttle, bottom cable is kickdown):



Problem #2:
Holding the kickdown cable sleeve in position. This is where I made like $2.50 back on the raping above. I had a spare LQ4 throttle cable bracket on hand. I took the spare, hacked off the unnecessary section, enlarged the mounting hole with a file, and drilled a hole to mount the bracket. Look at the throttle cable bracket for a before/after time lapse:



Problem #3:
The stock kickdown cable isn't long enough for the LQ4 application. Part no. ATP-Y754 to the rescue. This sucker has plenty of adjustability and at around $28 helps a brother save some face when the topic of build cost arises with a significant other.

[jpstaub]

What to do about the air intake problem? I like to have my cake and eat it too so I was bound and determined to:
1. Keep the stock Mass Air Flow (MAF) sensor,

2. Locate the air filter element in a location that would remain reasonably cool.

I wasn't able to find a complete kit ready to install but I did manage to find something that requires minimal modification. Chrome Intakes offers a kit for 99-06 Chevy Silverados which my system is based on.

Parts list to put an air intake together:
1. 99-06 Chevy Silverado kit from Chrome Intakes

2. Reducing Hose Insert 4" to 3.25" (40R323) from IntakeHoses.com

3. Reducing Hose Insert 4" to 3.5" (40R35) from IntakeHoses.com

4. Rubber Elbow 4" ID X 45 Degree (45L40) from IntakeHoses.com.

Some modification of the original kit is required (all done with hand tools like a hack saw and 3/8" drill motor). First, shorten the air filter side of the aluminum intake tube. Second, cut off extraneous mounting arm and set aside. Finally, use extraneous mounting arm material to fabricate a simple mounting bracket that catches one of the two alternator mounting bolts.

In the picture below you can see how the simple mounting brackets intercepts the intake tube mount point to make the system stable:



The following picture shows how the 45 degree angle places the filter in the horizontal plane. The 4" to 3.5" inch insert is used on the throttle body side of the MAF sensor. The 4" to 3.25" inch insert is used on the air filter side of the MAF sensor.



This last picture show how the 45 degree angle places the filter in the vertical plane:



Overall, a clean installation that still allows for the fitment of the engine control computer and relay/fuse block which will be explained in a subsequent post.

[jpstaub]

Upper radiator hose - Dayco E71989 or 2004 Chevy Silverado 2500 with 6.0L

Lower radiator hose - Dayco C72023 (unknown what this goes to but it fits)

[jpstaub]

With all the additional horsepressure on tap I thought it'd be a good idea to upgrade the radiator to a 4 row unit. The 4 row was a stock item but upgrading a truck that didn't have one originally takes some extra parts.

I got the following items from LMC Truck:

Radiator Retainer - Lower 32-0960
Radiator Retainer - Upper 32-0965
Radiator Support Pad 32-0955.

Of course the lower radiator retainer setup is different for the 4 row trucks but there was no way in hell I was:
1. Taking the original support apart,
2. Buying a new support which was bound to be spendy if I could manage to find one.

What I did to install the lower retainers was:
1. Drill out the rivet holding in the old retainer,
2. Drill and tap a 5/16"-18 weld nut for a 6-32 Button Head Cap Screw (BHCS) which was mounted to the underside of the radiator support,
3. Notch the upturned lip of the radiator support for the longer 4 row retainer,
4. Bolt down lower retainer using 5/16"-18 BHCS.

Viola! 4 row radiator that looks like it came with the truck.

[jpstaub]

We must have gas!

For acceleration use GM part no. 15040848.

[468BIGBLOCK]

I like them lsx engines!! great work.

[jpstaub]

Coolant overflow tanks weren't part of the deal in '72. To keep the truck from pissing coolant a universal overflow tank (part no. 36-4086) was ordered from LMC Truck.

To keep the build from becoming too environmentally conscious, the charcoal canister was removed, the charcoal canister bracket was removed from the original mount, and the universal tank was installed on the original mount. The picture below shows how the modification turned out.



The tank was subsequently turned around due to a clearance problem between the inner fender and the lower hose position.

[jpstaub]

An LQ4 comes with sweet aluminum cylinder heads that have modern small metric access holes in them. I am not a fan of boring large old school holes in delicate new school assemblies. As a result, finding a temperature gage sender became a significant problem. Added to the constraints was the limited amount of room available for a sender because of the factory rear-most engine location. Temp sensor adapters from places like Street and Performance are available but they're too damn long, are expensive, and they look ugly....

VDO to the rescue. Fortunately there are still people out there that make their own parts and publish actual specifications data. Part no. VDO-323092 is almost a perfect match for the application. The resistance vs. temperature curve is off but not enough to notice much of a difference on the gage. The gage still displays a normal temperature operating range giving the operator a sense of how the engine is feeling. The picture below shows the sender installed (look to the back of the cylinder head).

[jpstaub]

The old timers remember when part stores carried solenoids for starters like candy stores carried lollipops. Well, it's a new world order out there now buckaroo.

If you manage to snap one of the cheap ass terminals off your LQ4 junkyard starter while trying to take it apart and clean it because you're an anti-corrosion fanatic all is not lost. Get yourself a new solenoid using universal interchange no. 10475646 and save a couple hundred bucks or a trip to the "recycled parts yard."

For those that enjoy trivia, LQ4 starters are part of the PG260 series of Remy starters. The "PG" stands for permanent magnet geared reduction. That's how Remy reduced the size and weight of their starters.

[jpstaub]

Because Generous Motors is hooking me up with the squeeze and bang of the suck, squeeze, bang, blow partnership all I had to worry about was the suck and blow part.

This post is about the blowing, or exhaust, system.

The overwhelming majority of LSX swappers appear to rely on Trailblazer SS exhaust manifolds if they're not going headers of some variety. I didn't think that would work for me because the engine is located too far back in the frame. As a result, I thought the Trailblazer SS manifolds would run into the firewall. This may not be a valid thought since I never tried the Trailblazer SS solution (maybe someone with first hand trial fit experience can comment). Instead I started looking for exhaust manifolds that looked a lot like the original V-8 manifolds. In other words, I started looking for something that dumped straight down.

Be advised, I'm posting pictures of the Corvette manifolds because there are a lot of gomers out there advertising stuff without knowing what they're talking about. It's better to go by the pictures if you can.

Before we get into the Corvette stuff I can say that Express 3500 van manifolds will not work. I've got two sets if anyone is interested.

My first attempt at a solution with Corvette stuff was C6 manifolds ($150 a pair) like the one pictured below. The C6 manifolds didn't work. They ended up being so short the collectors interfered with the top of the frame.



For my second attempt I went with '01-'04 C5 manifolds ($125 a pair) like the ones pictured below. The heat shields had to be ditched because they interfered with the frame rails. Also, I had to clearance the bottom frame rail but not to a point where structural integrity was jeopardized. The great thing about these manifolds aside from being cheap is that they flow like headers according to the performance magazines.



Here's a picture of the driver's side clearancing.



And a picture of the passenger's side clearancing.



In addition to the above C5 manifolds you'll need C5 Corvette collector flanges (LS1005 from Vetteworks) unless you can score flanges from an original vehicle.

Exhaust manifold gaskets are part no. 12576221. You'll likely have to order them from the dealer since nobody seems to stock the damn things.

Warning! Each exhaust manifold stud costs $10. Get manifolds with good studs if humanly possible or standby for a raping.

Finally, stock LQ4 O2 sensors will fit without a problem.

[jpstaub]

There's been a lot written on the flex plate problem for LSX applications. For LQ4's from 3500 series vans that used 4L80e's going to a TH350 (the same applies to a 700R4) is simple. The stock flex plate setup is all you need. If you're mating another engine code to a TH350 as long as that code used a 4L80E you should be set.

Steps:
1. Select three victim bolt holes on stock flex plate.

2. Mark flex plate hole elongation as required.

3. File holes and check fitment with TH350 torque converter.

That's it.

[jpstaub]

You'd think finding block-off plates for '01-04 C5 exhaust manifolds would be easy. It probably is if you're not as challenged as I am about what things are called on modern Corvettes.

To block off the holes in the manifolds pictured below you need what is known as AIR block off plates. Part no. KOK-9126BO is one option. I got the gaskets for the plates from the stealership (part no. 12553617).

[jpstaub]

LQ4's from vans come with a loooong dipstick tube. Half the tube can be removed leaving a standard length dipstick tube. Throw indicator, engine oil level part no. 12622055 in there and call it complete.

[jpstaub]

If your LQ4 was originally equipped with an oil cooler you'll need to block off the holes in the oil pan. What you'll need beyond fasteners is:

Cover, Engine Oil - Part no. 12577903
Gasket, Engine Oil Pan - Part no. 12611384.

[jpstaub]

There are lots of options for this one. What the system needs:

1. A reservoir to provide a constant supply of fuel to the high pressure fuel injection pump (approximately 60 psi),

2. Filter(s),

3. High pressure regulator (50ish psi),

4. Return line to fuel tank.

I chose to use a stock non-evap tank for this swap. '72 tanks came as either evap or non-evap. Non-evap tanks don't have provisions for passing fuel vapor to the charcoal canister and are therefore physically more straight forward. I also repurposed the charcoal canister mount for the coolant overflow tank so a non-evap tank was in order.

Some trucks had senders with a return line, others did not. If your sender has a 3/8" supply only you'll need a sending unit with return line. Part no. 129011 from Eckler's Truck Parts or similar will get the job done. The return line is 1/4".

The picture below shows custom bent fuel lines from the tank through the cab floor. I used coated 3/8" and 1/4" steel brake line. You can also see a ball valve which allows the guy who has to service filters or pumps to secure fuel. For soft line stuff I used brass pushlock fittings sourced from Discount Hydraulic Hose. For hard line stuff I used aluminum line with the associated tube nuts and sleeves. Hard line is the cheapest/surest way to go but more difficult to work with. The pushlock stuff is super easy to work with (hint: coat fittings with a dish soap/water mix prior to pushing on hose for less struggle).




In the picture below you can see the ball valve, low pressure fuel filter, and the low pressure Carter P4070 fuel pump. Be sure to put thread sealer on all your NPT connections otherwise you're going to have leaks when you pressurize the fuel system (ask me how I know).




In this picture you can see how the low pressure fuel pump was mounted and how the fuel line is routed across the truck. On the right you can see the custom surge tank (approximately 1 quart in volume) that keeps the high pressure fuel pump from starving. Starving the high pressure pump will result in a very short service life and frequent actuation of the ball valve referenced above.



Below you can see the surge tank with four outlets: 1. 3/8" feed from low pressure fuel pump, 2. 1/4" return to main fuel tank (upper fitting), 3. 3/8" return from high pressure fuel filter/regulator (middle fitting), 4. 3/8" supply to high pressure fuel pump (lower fitting).



4" square tube was used to fabricate the surge tank. Male aluminum AN nipples were used to make connections. Russell push on fittings were used as required.

The only change made to this setup after this picture was taken was a 3/8"x1/2" splice in the feed line from the surge tank to the high pressure fuel pump. The high pressure fuel pump fitting is about 1/2". I thought I could make 3/8" line work but it didn't. Use 1/2" carburetor fuel line and all should be well.

Note: for all the part numbers and suppliers to duplicate this setup see the bill of materials document linked at the beginning of this project post.

[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