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I also got the last big piece in: headers. Swap headers is one of those sticking points with these swaps. There just isn't a huge LS swap crowd for them, so there were only a few small sources for swap headers. Most used Melrose swap headers, but their supplier backed out on them, so they don't make them anymore. (also, they were only 1-3/4" primaries). There is some other site, but again, not stainless and 1-3/4" primaries. In the end, I bit the bullet and bought a set from BRP Musclerods, they are stainless with 1-7/8" tubes. Not cheap, a touch over $1000, but there just aren't options, and honestly, not really any difference in price to most nice mass market stuff... blackheart, kooks, or the Sikkys, Church boys, niche swap headers. They only guarantee they fit if you use their engine mounts, which I am not (I think they only have mounts for the pre-LT1 cars). So, they arrived today, and in the end, they fit well and I'm happy with the quality.
They do just kiss the engine mounts on both sides, so I'll clearance those a little. But the fitment is great, ground clearance and output placement is perfect. They have decent shaped collectors with merge spikes. Getting them in place was not easy though. The drivers side could not install from the bottom, no way to get past the engine mount. But initially they didn't fit from above, either. Once I removed the alternator and coils/bracket, I was able to sneak it in, and once in there, there's lots of space. On the passenger side, they couldn't install from the top, though, they hit the engine mount. From below, they again didn't go in at first, but it was just hitting the old LT1 fuel hoses that I needed to remove anyway. Once those were out, they slid in place. They are even with the bottom of the oil pan, and have great placement for building the rest of the exhaust. I'll use some band clamps to hook up to 3" exhaust once I get around to building it.
Most of the accessory drive is in place. I need to figure out a better fitting for the suction port on the PS pump. All of the 3/8 NPT fittings I have found don't feel like they have a big enough port. Will see what I can come up with, or I just say screw it and buy a new C5 pump..
Still waiting for the SD508 compressor to come. It's going to be a tight squeeze but I think it will fit
I lost the intake-to-head seals for my FAST, so the intake had been sitting. New seals came yesterday, and after fighting with that dang manifold for a few hours for different reasons, I got it all installed today. I'll grab pics and details tomorrow.
So hopefully by the weekend, I'll have most of the accessories done, headers fully bolted down, cooling systems plumbed, and then I can start on cleaning up the wires and laying out the Holley.
Nice progress. Just fired my C4 ls swap up today.
Had nothing but setbacks even after I got my term x. Wasn’t showing rpms and after 2 new ac Delco cam and crank sensors i was thinking I’d be pulling the engine today but decided to try a ckp sensor on a spare 5.3 I picked up and it fired up. Woo hoo!
Still working on this swap. Last summer got pretty crazy, and we spent most of the time keeping the family safe, sane, and happy, and working on my other cars. But it's thawed out here in Michigan, so it's time to finish this one and enjoy it.
The main thing that stopped me, was accessory drive. I really want to retain AC on this car, but it's not easy. There isn't a bracket on the market that fits. In short, for now, I've got the accessory drive done, without AC, and I'll get the AC figured out later, or next year. It's too easy to let a little item derail you. I have made some mockup brackets out of plastic (old cutting boards FTW) and I Will machine up some aluminum ones later... but again, I dropped it on the priority list. The rest of the accessory drive is more or less C5 stuff.
Cooling system is all plumbed, with a new radiator. The LT1 had steam ports also, and a 2 piece upper hose, so it was pretty easy to make the LS bits meet up with those. I put in a new AC condenser and a transmission cooler as well, when I had the shroud open.
The main items left to do are: fuel system and ECU/Wiring. I need to get a throttle cable installed as well, and fab up the exhaust. I'm sure there's a few other items I'll get some photos up soon of how things look.
For now, I'll leave this one. I wanted to switch to the "A Mold / ZR1" style rims, and the existing tires were a little hard/old. So I got a new set of wheels 17x9.5 F and 17x11 R, and new tires. Conti ECS 275/40R17 fronts and MT ET Street SS 315/35/R17 rears. Crazy that these were actually the factory correct tire sizes for the C4 ZR1s and Grand Sports. The wheels have more spoke clearance than the sawblades, so they allow the use of C5 or C6 front brakes, which will be a 2022 project.
baby steps... got the fuel pump done. Its always funny how stuff can *almost* fit, but can be a total pain in the butt.
I had an Aeromotive stealth 340 on the shelf. The C4 pump module is very easy to access, it comes right out the top, once the access door is unbolted. The inlet size is different than the C4 pump, so I had to use a different sock. This required a little trimming to the bottom bracket. But this then had the sock sticking sideways, which didn't clear the sump tray in the tank. But rotating the pump caused the wires to be too short.. Anyway, after a bit of tweaking it, I found a rotation that fit everything.
The wiring was also upgraded, I am using a high current bulkhead fitting and in-tank harness from Racetronix out of Canada. That also includes a new pigtail on the outside of the tank. I will running a new power feed straight from the alternator, with a new relay controlled by the Holley ECU.
That's all I had time for yesterday. Work remains busy, so I only get an hour or two here or there. Spring Break is next week and I hope to get more time.
The LT1 already has 3/8 stainless feed and returns, so the lines themselves are good. Note: The hose clamps at the module are not my preferred setup, but those are the factory clamps/setup, so for now I will leave them. The rubber hoses are then crimped to the stainless feed/return lines. Next up will be the regulator. I have an aeromotive regulator, and will be running -6 PTFE lines from the stock lines by the fuel filter (which is near the engine on the passenger side rail).
The C4 wheels look better than the sawblades any day of the week. I'm watching the thread. Its very cool and yet different.
I've always thought the A-Mold wheels (found on the 94-95 ZR1s, 95 pace cars, 96 Grand Sports[black wheels], and the 96 Collectors editions) are the definitive wheel for a late C4 corvette. I was doing my usual thing and saving money, and was just going to use the sawblades. But I was able to sell the LT1 from this car, as well as the ECU and a few other parts, so I had money in my paypal account and was able to get them. Apparently, the 1992 LT1 ECUs are rare, I was able to sell it for better than $500 on ebay within a week.
Make sure that the sensors that protrude into the Oil cooler plate don't restrict the oil volume. I've heard of oil starvation stories from sensors blocking the flow.
Make sure that the sensors that protrude into the Oil cooler plate don't restrict the oil volume. I've heard of oil starvation stories from sensors blocking the flow.
It looks a little blocked in the pic, but there is a ton of depth there around the tip of the sensor. LOL, but I started on the wiring, and realized that is a water temp sensor I installed, so I need to chuck the oil temp sensor into the lathe and re-thread it.
Finished up the fuel system. To go with the upgraded in-tank and bulkhead wiring, I ran a new 10 gauge feed back from the engine bay. I de-pinned the power wire from the racetronix harness and moved it into a new 2 pin connector, and ran an additional heavy ground strap to the frame. This finished up the pump module. Later this week, I'll wire the relay, running power directly from the alternator stud.
Moving on to lines, the LT1 cars already have adequate 3/8" stainless lines. The fuel filter is up by the engine bay, as well as a convenient splice point in the return line, were the OEM return crimped hose connects.
Both the splice and the fuel filter are Metric (M16 x 1.5) O-ring fittings. Its the same as some power steering fittings, so its easy to find adapters to -6AN. These are the ones I used:
I built up lines out of -6AN PTFE hose, and gave each some thermal / scuff protection where they are close to the headers and/or might be touching against body panels. A 1967 Plymouth Valiant trunk makes a nice convenient work table
I put the regulator up on the right side. This area used to contain a couple stand alone modules for the LT1. I believe the throttle position sensor module and few other bits that were removed.
Down below, a new fuel filter was installed and the AN lines connected..
Then the insulation slid in place.
I need to do a sweep, as I'm sure I am forgetting things, but I am getting close to testing and trying to fire it. I need to do a bunch of wiring, including the Holley. I need a throttle cable (which I predict to be a complete PITA, if you've ever seen the available space to access the gas pedal in one of these...), a power steering hose, and some temporary exhaust turn downs so I can have something to put the O2 sensor in. I need to pull the transmission pan and verify the fill level (or scribe a new one). Then its on to fluid fills and pressure tests, then see if it will start.
Next up was getting a throttle cable. On the 1992 LT1 cars, the throttle cable is rather complicated. You have a cable from the pedal and a cruise control cable from a vacuum actuator, these are inputs. They go to the ASR thingamajig. Then there is the cable out from this to the throttle body, and then a 4th cable, being the TV cable to the 4L60. Essentially, its like an early version of DBW, which used cables as inputs and outputs to control a cable driven throttle body.
Anyway, all of this complexity was removed, and I'm going standard cable from the pedal to the TB. The suggested cable most use is a 36" universal Lokar. Rather than using the Lokar end, however, I pulled the plastic clip end from a Silverado throttle cable that I had laying around. This is just a pressure fit onto the GM cable. THe Lokar ends are the same and pull off by hand. The sheath diameter is the same so you can swap them. This fit the firewall with a slight modification, and is a lot easier to install compared to trying to thread on the end of the lokar one under the dash. I also shortened the Lokar sheath by about 4-5 inches to not have so much looping under the hood.
So, it's threaded Lokar on one end, and traditional GM clip in on the other end.
A few acrobatics were still required to get the cable and pedal reinstalled....
The other end bolts up like normal, I used an F-body LS1 throttle cable bracket. My son and I verified we have full pedal travel and full opening of the TB blade.
Next up is wiring. Spent a few hours tracing, labelling, and trimming out wires. I re-purposed the relay for the old Air pump, to be my fuel pump relay. This is the same relay used for each of the fans and the AC clutch. I like having the same parts, so I can steal/swap if I need to troubleshoot something. The power input to the relay comes right from the main stud on the alternator.
Starting to do wire layout. I'm reusing the charging wire from the old 140 amp alternator, but I will be using a 2 pin alternator that came with this motor, and controlling it via a PWM from the Holley. So since they went to the same place, I used the old (12ga) Voltage Sense wire in parallel with the main charge wire, to bulk up the size of the charge wire a little bit. I did leave the original L (Lamp) wire in the bundle, in case in the future, I decide to go back to a 4 pin style.
I have the Holley 90% wired in at this point. I need to extend the wire to reach the cam sensor, and extend the wires on the fuel pressure connector to head all the way over to my regulator. Once the system is dialed in, I'll swap the mechanical gauge out for an electrical sender. The Holley will sit underhood, where the old LT1 ECU was located. Lights towards the driver, connectors angled downward. This area should stay dry and I don't plan to drive it in the rain anyway. Its loose now, but once I get the motor fired and all is well, I'll finish routing and cable ties. I'll also make a plate to mount the misc relays and fuses. For someone doing this swap: Note that you need to cut and solder on the correct VSS plug. My 92 plug fits the 96 VSS, the original Yellow wire goes to Purple on the Holley, the original Purple wire goes to green on the Holley, although I don't know that it really matters. While I was under there, I pulled the 4L60e pan and verified the fill mark on the dipstick, a step highly recommended by Performabuilt.
I found a cheap (because broken..) LS3 C6 air intake... its close to fitting, but will need some cutting or heat gun work. Its a little thicker than the LT1 intake where it crosses the top of radiator shroud. I could cut the shroud also, but it's a PITA to remove, and I prefer to leave it whole to maintain best air flow through the radiator. We'll see..
So, what's left... not much
I need to:
Connect the power steering cooler to the return on the reservoir. I plan to do bend hard line to fit nicely and just have a few inches of rubber line at each end.
Redo the transmission cooler lines at the ends. Right now, I just have a flare on the end of the line, and the hose is shoved over it with a clamp. I didn't feel good about it when I did it, I find this ends up weakening the rubber line and I had a set fail like this on a Jeep once. So I have some compression hose barb fittings to cut in. I'd rather do it now before I fill the transmission.
Finish the wiring mentioned above. I need to wire the relay to provide switch battery to the transmission as well, and tap the brake signal.
Get the O2 sensor temporarily in place. I'm anxious to fire the motor to make sure all is well, and I haven't fabricated an exhaust for it yet.
Jump the fuel relay and set the pressure to 58 PSI.
The gas smells/looks fine, but I might siphon most of it out and put in fresh and/or put in some octane booster. Its 93 in the tank now, but its 3 years old.
Then it's fill with fluids and do the Holley setup. I was thinking I might use my pressure bleeder to pump the oil into the engine though one of the ports I have at the oil cooler bypass.
Hopefully another week or so and I can fire it. I really need to go buy a bottle of Argon and start on the exhaust...
Next up was getting a throttle cable. On the 1992 LT1 cars, the throttle cable is rather complicated. You have a cable from the pedal and a cruise control cable from a vacuum actuator, these are inputs. They go to the ASR thingamajig. Then there is the cable out from this to the throttle body, and then a 4th cable, being the TV cable to the 4L60. Essentially, its like an early version of DBW, which used cables as inputs and outputs to control a cable driven throttle body.
Anyway, all of this complexity was removed, and I'm going standard cable from the pedal to the TB. The suggested cable most use is a 36" universal Lokar. Rather than using the Lokar end, however, I pulled the plastic clip end from a Silverado throttle cable that I had laying around. This is just a pressure fit onto the GM cable. THe Lokar ends are the same and pull off by hand. The sheath diameter is the same so you can swap them. This fit the firewall with a slight modification, and is a lot easier to install compared to trying to thread on the end of the lokar one under the dash. I also shortened the Lokar sheath by about 4-5 inches to not have so much looping under the hood.
So, it's threaded Lokar on one end, and traditional GM clip in on the other end.
A few acrobatics were still required to get the cable and pedal reinstalled....
The other end bolts up like normal, I used an F-body LS1 throttle cable bracket. My son and I verified we have full pedal travel and full opening of the TB blade.
Next up is wiring. Spent a few hours tracing, labelling, and trimming out wires. I re-purposed the relay for the old Air pump, to be my fuel pump relay. This is the same relay used for each of the fans and the AC clutch. I like having the same parts, so I can steal/swap if I need to troubleshoot something. The power input to the relay comes right from the main stud on the alternator.
Starting to do wire layout. I'm reusing the charging wire from the old 140 amp alternator, but I will be using a 2 pin alternator that came with this motor, and controlling it via a PWM from the Holley. So since they went to the same place, I used the old (12ga) Voltage Sense wire in parallel with the main charge wire, to bulk up the size of the charge wire a little bit. I did leave the original L (Lamp) wire in the bundle, in case in the future, I decide to go back to a 4 pin style.
I have the Holley 90% wired in at this point. I need to extend the wire to reach the cam sensor, and extend the wires on the fuel pressure connector to head all the way over to my regulator. Once the system is dialed in, I'll swap the mechanical gauge out for an electrical sender. The Holley will sit underhood, where the old LT1 ECU was located. Lights towards the driver, connectors angled downward. This area should stay dry and I don't plan to drive it in the rain anyway. Its loose now, but once I get the motor fired and all is well, I'll finish routing and cable ties. I'll also make a plate to mount the misc relays and fuses. For someone doing this swap: Note that you need to cut and solder on the correct VSS plug. My 92 plug fits the 96 VSS, the original Yellow wire goes to Purple on the Holley, the original Purple wire goes to green on the Holley, although I don't know that it really matters. While I was under there, I pulled the 4L60e pan and verified the fill mark on the dipstick, a step highly recommended by Performabuilt.
I found a cheap (because broken..) LS3 C6 air intake... its close to fitting, but will need some cutting or heat gun work. Its a little thicker than the LT1 intake where it crosses the top of radiator shroud. I could cut the shroud also, but it's a PITA to remove, and I prefer to leave it whole to maintain best air flow through the radiator. We'll see..
So, what's left... not much
I need to:
Connect the power steering cooler to the return on the reservoir. I plan to do bend hard line to fit nicely and just have a few inches of rubber line at each end.
Redo the transmission cooler lines at the ends. Right now, I just have a flare on the end of the line, and the hose is shoved over it with a clamp. I didn't feel good about it when I did it, I find this ends up weakening the rubber line and I had a set fail like this on a Jeep once. So I have some compression hose barb fittings to cut in. I'd rather do it now before I fill the transmission.
Finish the wiring mentioned above. I need to wire the relay to provide switch battery to the transmission as well, and tap the brake signal.
Get the O2 sensor temporarily in place. I'm anxious to fire the motor to make sure all is well, and I haven't fabricated an exhaust for it yet.
Jump the fuel relay and set the pressure to 58 PSI.
The gas smells/looks fine, but I might siphon most of it out and put in fresh and/or put in some octane booster. Its 93 in the tank now, but its 3 years old.
Then it's fill with fluids and do the Holley setup. I was thinking I might use my pressure bleeder to pump the oil into the engine though one of the ports I have at the oil cooler bypass.
Hopefully another week or so and I can fire it. I really need to go buy a bottle of Argon and start on the exhaust...
I may have missed it, what are doing for gauges? I love the 1990-up dashes. Are you piggy backing?
I may have missed it, what are doing for gauges? I love the 1990-up dashes. Are you piggy backing?
For now, I will use the stock 1992 cluster. Now, I have a few small issues that I need to work out.
1) It's a 6k tach, I will be revving a good bit higher than that.
2) The CCM isn't going to be happy that the stock ECM is gone. It will give me a SYS error on the LCD.
The 4k PPM speedo signal (0-12v square wave) I can generate from the Holley (low side PWM) and a pull up resistor to 12v.
The tach will be generated by the Holley
The LT1 water temp sender was turned down and rethreaded to the correct metric size, and is installed in the passenger head
The LT1 Oil temp and Oil pressure senders are installed in the oil cooler bypass/block off plate on the LS2.
All those things are stand-alone, and should all work.
The digital stuff that you can toggle with the DIC switches won't work, but I'm not really concerned. I am planning to re-do the DIC / switch area, to reduce the indicators for the functions that I have removed, and integrate the Holley 3.5 screen in there. I'll do 3d print / filler / paint to match as best as possible.
If I decide to keep the stock cluster, then I will grab a set of 8k gauge faces (theres a guy selling on the corvetteforum), and re-cal the tach to 8k. And I might put an oscilloscope on the LCD lines and decode the protocol. Its not too hard, its a segmented LCD, so not too much info each frame. And then create my own display.
Note: I have been an engineer in Detroit for 25 years, most of which is either designing instrument clusters for GM and Chrysler, or designing their on-board networks. So I have a good bit of experience doing this, and building one-off clusters for demos, auto show cars, etc.
Or, I got the other way, and design something completely custom, possibly integrating a Holley 12.3 or 6.86 dash. Compared to what I am used to, most Holley installs are plain looking to me, with boring graphics. But we'll see.
I have been wanting to update my 90 L98 to a LS3/LS2 and this has always been one of my struggles is that i want it to look at stock as possible from the inside with most of the dash working as it should. Im interested to see what you do here.
Done Connect the power steering cooler to the return on the reservoir. Done Redo the transmission cooler lines at the ends. Done wire the relay to provide switch battery to the transmission
To Do, after it fires: tap the brake signal. (Not needed to fire, just for TCC) To Do, after it fires: O2 sensor / Exhaust (I will leave unplugged and not installed)
Remaining To Do before Attempting to Fire:
Jump the fuel relay and set the pressure to 58 PSI. Fill with fluids and do the Holley setup.
Double check grounds are all in place. I have the Holley grounds on each head, but I think I will add a new ground strap to each head as well.
I got the CAM sensor tackled, it was a bit of a pain. I have the TBSS front cover, including the OEM pigtail that mounts the connector down by the pan. I probably could have swapped to a non-pigtail setup, but I didn't realize the issue it'd cause. So, this caused 2 problems: The Holley wire was *just* a little short. I maybe could have stretched it but wires should never be in tension or they will fail over time. So, I had to cut and splice in 6 inches of wire. And, of course, Holley is using shielded wire here. I don't think the OEM is shielded, but, since Holley used it, I played along. I used a chunk of shielded cable that came from the old LT1 harness, and very carefully stripped only enough to solder and get heat shrink on there. I heat sink the wires enough to keep the heat shrink from melting before its in place, since its right next to where I'm soldering. Once those were done, then the internal ground wires that ground the shielding were also soldered. Then the whole assembly is wrapped in EMC foil, I use an adhesive coil tape for this, its what I always used when I did EMC testing for the OEMs and we need to shield cables or other high speed stuff. Verify your new shielding overlaps the old, and has 0 ohms to the internal shield ground wire. Another layer of heat shrink over the whole mess, then into a new longer braided loom. Blech, a good hour of careful work with reading glasses, but its done now.
And then.. the connector doesn't fit..
This is the second issue: the connector is slightly different. Enough that you could easily jam it in there and break it if you tried, I suppose. Attached is a picture of the 2 types. Luckily, I have spare harnesses around, and was able to swap this connector with my original TBSS harness. It's just Metripack 150 connectors, so the terminals interchange. So this was easy, just de-pin both connectors and swap them. And boom, its installed and all set. I'm posting this just in case someone runs into the same issue.
Here's a picture (this is from Haltech).. but note: This is 5 volt sensor, not 12 volt as they show.
Sorry, I don't know the connector body part number. There are lots of pigtails available, but I just robbed one from my spare harness, so I didn't have to order anything.
So, One of the practices that I use, is when I have to cut back wires that I will not use, I trim them to a good place, and I bend the ends over and seal them in tape. Then, I use those little electrician's number stickers and mark the wires, and I record them in my notes. (LOL, my Dad was an electrician, and I'd always steal those stickers from his toolbag so that I could play with them. 40 yrs ago.. time flies... and those dang stickers haven't changed a bit. ). In an ideal world, I'd remove all the unused stuff from the harness, but, well, go look at a LT1 C4. Its a point to remember, these weren't really track oriented cars, more of a luxury sport/touring car. They have a ton of features we take for granted today, but were innovative back then. So the wiring is rather complicated, and everything on a vette is 10 lbs squeezed into a 5 lb bag.
I accidentally got my oil pressure wires confused with the oil temp wires, and clipped it. This is the one that drives my instrument cluster gauge. I want the Gauge cluster sensor active, so that I can watch for oil pressure when I first crank it, likely with the Holley ECU unplugged. So, luckily, I didn't know what that wire was (#5, mystery connector), but I labelled and marked it. So now I just go back into the bundle, grabbed the #5 wire, and I'm good.
This thing is so close to first fire. Here's a huge milestone.... The Battery went back in for the first time since it went into the shop a year ago to start the swap. Its hard to see, but I got a set of extended post/bolt combos, that are like a double ended bolt. This gives a threaded stud and nut sticking out of each terminal. I have plenty of room for these, and the wheelwell is plastic. (I also have covered boots for them, so little chance of shorting). These extra studs give a perfect place to bring all of the required ECU leads. They arne't visible, but I have all of the wires required to go to battery neatly loomed and soldered to a pair of heavy copper lugs and heatshrinked.
So, plugged in the battery, lol, I had the key and in the run position, so the radio turned on and scared me a bit. But I keep a current clamp on the line to watch for trouble, all good. I jumped the fuel pump on, and primed the system. No leaks at all, so I got the fuel pressure set to 58 psi.
At this point, I just need to top off fluids, and crank for oil pressure. Then time to do the Holley setup wizard.
Sorry, I don't know the connector body part number. There are lots of pigtails available, but I just robbed one from my spare harness, so I didn't have to order anything.
The keys are the bigger lock tab, and the little wings/notches on the sides.
I believe you are correct. I tracked it down in the Delphi catalog.
I also found something else that nifty. Apparently, some connectors have an optional TPA that is called a "conduit TPA." Here is the one for the 3 cavity connector:
What these allow you to do is fully seal the back of the connector with either tape or heatshrink. I plan on adding these to my Holley Terminator X harness for the cam and crank sensors. I like using the little pigtail on the front cover because it actually puts the cam sensor connector in a much more accessible spot. I suspect my harness will be too short as well, but I already have 25 feet of shielded cable ready to go just for this occasion and also for the VSS wiring that I plan to add.
05-28-2020, 08:33 PM
I've always thought the A-Mold wheels (found on the 94-95 ZR1s, 95 pace cars, 96 Grand Sports[black wheels], and the 96 Collectors editions) are the definitive wheel for a late C4 corvette. I was doing my usual thing and saving money, and was just going to use the sawblades. But I was able to sell the LT1 from this car, as well as the ECU and a few other parts, so I had money in my paypal account and was able to get them. Apparently, the 1992 LT1 ECUs are rare, I was able to sell it for better than $500 on ebay within a week. 
