Corivus' 1991 740SE v8 swap

So the family went to bed(woo) which meant that I had free time again. So I decided to address my fuse box mounting and how best to protect it. While at the junkyard I grabbed the upper fuse box cover out of a 08(?) 1500 because the design doesn't change much. But I was worried the lower portion wouldn't match, surprise surprise it should work. My original plan was to make this plate. (dashes are bends solid are cuts)



And then hack up the fuse box upper cover, while doing the initial trimming down of the upper cover. I put the cover in the place of where the fuse box went on and had a moment of "Oh.... this could fit if I trimmed these things. After some snipping and a lot of "hah!" I managed to get to this point. Its not perfect but once I file down some stuff it'll be nice and clean.




the weird curve at the bottom is oem and kinda bothers me, I think I may trim everything a bit lower and might still use the plate with some rubber isolators to keep everything from grounding or maybe even go back to the jy and grab the lower portion of the case so its mostly "oem"

very cool, hope it makes good noise and no trouble first start.

well right now i'm trying to get the fp to prime and the starter to engage to make sure there's nothing wrong but of course I've run into issues and only getting constant clicking from the fp relay on the gm side. thought it was the relay and replaced it with a new one and nope still not working. so I'm gonna add some more grounds and go from there.

So this is an end of the week, oh I should update this with things because any progress is progress right?? Well maybe not but here goes..

So I started trying to fit the OEM coolant overflow bottle and it was interfering with the a/c compressor to dryer line so I needed to space it out. So I decided to make this, just a few spacers some sheet metal and bolts and $5 later I can mount the overflow bottle with no issues.




Painted it all black with rust prohibitor and now no one will know... except well everyone here knows so everyone will know.






Next up was to get the transmission in place and on a mount of some sort, so I started off with the stock Volvo trans cross member.



Still pushing back a little and not enough clearance from the firewall to the back of the engine. So I added the gm trans mount and now I have some decent clearance, enough to fit my hand behind the firewall somewhat awkwardly.





I also attempted my first test fire and have narrowed the clicking down to the fuel pump but I'm suspecting its either a security feature that's enabled itself or I need more grounds (right now there are 3 block to chassis grounds) or I just need to send 12v switched to the trans if I want to be able to hear the fuel pump cycle.

https://youtu.be/7i1WHHl36OA

Thankfully thelostartof is super duper awesome and will be coming over on Tuesday to help me figure out what's going on with the clicking and make a proper trans cross mount and bring some of my other odds and ends.

This is a small update really, all the big stuff is mostly done outside of exhaust.

First things first we measured the final trans height and measured for the driveshaft. Came up for a solution for the transmission mount. At this point I sent off the driveshaft to be modified and got it back in about 4 days because I dropped it off Friday afternoon so it was really done in 2 days.




Got that installed and then moved back to testing out the fuel system after some back and forth we got 12v to the fuel pumps and found a few leaks, fixed most of them aside from one coming out of the fuel rail feed line that I made. I figured this would leak but wasn't sure as some things I was reading said it would be fine I'm wondering if I nicked it. So I made the whole line a full a/n line with PushLok hose and no more leaks.



Also modified the GM DBW pedal and made the template to build an adapter to run the gm pedal in the stock Volvo location.






Once that was done I addressed something I really wanted to get around and that's the fuse box. After going through a lot of back and forth I decided it would be easier to make a stand alone harness. Its been an interesting process that's still ongoing but hopefully once its done it will be a nice clean harness.



I still have some coiled up wires right now and that's mostly so I can read up on if those sensors are needed and delete as needed. Everything is taped up with painters tape so it doesn't make a huge mess and I can better wrap it off later.



This is the walkthrough I'm using right now on building my harness. https://lt1swap.com/Gen3_harness_mods_LT1SWAP_comHQ.pdf











Not sure if I've missed anything but kinda happy where I'm at right now but so antsy about getting this running. And here's what I'm missing at this point and keeping me from driving I feel like I might be missing something though.

Finish wiring harness
Finish cooling lines
Run signal wire to starter
Mount fuse box
Program and base tune the ECM
vac and charge ac system and search for leaks if any.
install temp exhaust downpipes and drive over to thelostartof's place to weld in the rest of the exhaust.

Nice work. V8, it just makes sense does it not?

it fits so perfectly, and so much more of an aftermarket for performance upgrades at better price points.

corivus said:

it fits so perfectly, and so much more of an aftermarket for performance upgrades at better price points.

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Agreed, reliable 300+hp with better MPG at a better cost? No brainer.

Why did you not go with a standalone harness? Our harness from BP was plug and play. It's one of the main reasons our V8 swap only took 30 days.

https://www.bp-automotive.com/

Tfest said:

Agreed, reliable 300+hp with better MPG at a better cost? No brainer.

Why did you not go with a standalone harness? Our harness from BP was plug and play. It's one of the main reasons our V8 swap only took 30 days.

https://www.bp-automotive.com/

Click to expand...

Because I am a glutton for punishment and I can say I did it all if I make my own stand alone, honestly though I should just grab the BP one. seems everyone is going with that for ease of use.

corivus said:

Because I am a glutton for punishment and I can say I did it all if I make my own stand alone, honestly though I should just grab the BP one. seems everyone is going with that for ease of use.

Click to expand...

It is an honorable challenge to take this on yourself. You'll know a hell of a lot more about your electrical system than I ever will.

Tfest said:

It is an honorable challenge to take this on yourself. You'll know a hell of a lot more about your electrical system than I ever will.

Click to expand...

hah thanks and thats one way to say it! honestly I am just as tempted as I was when first taking on making a new harness to use the bp one.

edit: to add just shot them an email to see if they had a harness that also includes a/c, I'm going to make a fuse setup for that as well as a/c is a must in az for a DD

terminator x is the answer, so much better then a stock ecu, gives you alot more room to grow once you get bored of the stock power level

cosbySweater said:

terminator x is the answer, so much better then a stock ecu, gives you alot more room to grow once you get bored of the stock power level

Click to expand...

Sadly backorders from April with Holley are still not filled and the current fulfillment date has changed from 11/19 to 12/30... correction apparently its tbd now. Otherwise I'd have had a Holley unit back in September.

edit: i will be using them next year for another project because part of me just wants to be all motor so I can retain a/c.

Quick update, mostly playing with wiring right now, waiting on hoses to come so I can start making my radiator lines. Of course the holiday's are delaying that, but I'm hoping to do the first test start this year, if not its not a huge deal. The Current DD I have is pretty comfy and the wife keeps jokingly asking if I'm gonna sell the 740SE (the answer is always no). Its a NA 00 V70 manual that's been fully optioned out, if it was turbo I'd be keeping this long term.



Also I can't find my n/a upper and lower radiator mounts so I just used the old turbo ones, everything clears which is nice but damn I want it to look cleaner now. who cares that I'm just going to be pulling the harness after I do a test start to sheath everything.



Nearly finished up the harness just gotta run switched power to the connectors to the a/c compressor and also make a connector for 12v+ signal request from the Volvo ECC to the GM ECM at pin 17.




Also I wanted to be able to place the tach module further away from the exhaust, this required extending the harness but once that was completed I mounted the tach module where the battery used to sit. I reused the volvo grommet for the gm dbw harness while extending it and it fits real nicely. I will still probably just go get a proper grommet from the hardware store so I have something that sits in night and snug. this one is a little loose and I don't want to have any engine noise in the cabin like my red 740 did.




And started planning on routing my wires since I wanted them to tuck a bit more once covered. So far its a lesson in patience but I've already had to undo some of the loom to make things exit in different places to get the harness as a whole to tuck around the engine neatly. On a side note is there any sort of extra shielding I should do near certain places on the harness?

Very short post with a video because December is busy for me and that's an understatement, between every weekend starting at 6am and ending at being home at 9am so far I'm ready for it to be January. I did however manage to sneak in some time to test out my starter which just kept clicking and not doing anything. Took it to the store and its bad so I got a new one. Here is the video of that:

https://youtu.be/NWLBBuo49Lo

Next step is to hook up the fuel pumps and coils and exhaust and see if I can get it to start up, once that happens then i need to make the lines for the trans cooler and make a mount for the cooler to sit on so its not completely blocking the condenser.

Between the holiday, getting sick (not covid) and my daughter getting covid I haven't had much progress (she's sick again in fact) I did some troubleshooting with Brenden over at lt1swap.com. After going through my setup he identified that I was using an 03 tac module with an 02 ecm, so we unplugged it and then this happened. I wasn't ready to have a first start as I didn't put the manifolds on yet since I'm still wanting to do some routing of wiring. The engine is healthy at least but I def need to get the upper and lower radiator hoses finished off which hopefully I'll have those mid February if shipping is to be believed.

this morning I performed another test start that I was ready for, lots of smoke but yeah... I need to get the exhaust squared away on this along with the other small odds and ends.

https://youtu.be/Xj21-ChAakQ

next steps after this are to make the cooling lines for the transmission cooler and get the auto shifter in place (this was a manual swapped car) and make linkage and then exhaust needs to get made.

Also I now have a working obd2 link so I can run diagnostics, which means I'll have to hook up the tach signal and some of the other bits soonish

awesome! cant wait to see it finished!

me either, that said I got it to run after swapping in the correct TAC module, now to pull it all apart and get the wiring shielded and cleaned up. DBW pedal is fully functional and it seems my codes are no longer tripping. however all the short starts are taking the toll on the battery so I need to toss it on my charger once I can find it.

Also I should say anyone using the gm ecm and going dbw try and get the 03 ecm because the 02 tac module is so much harder to find for some reason. I went to 5 different yards before I found one.

nothing super new, decided to ditch the volvo radiator and go with a custom ls swap one, using the becool 35223 which should come in today. also ordered a car water pump and am going to follow this guide to swapping it over and keeping the accessories the same.

No new pictures since the only thing that has changed is putting the volvo on the ground and fitting the shifter cable from a silverado 1500 (Holy smokes is it long) I'll take some later, but here's a video of me starting and showing a great idle, not letting it run for long since no coolant but right now its sitting happily at 50*c after 2 minutes of idling.

https://youtu.be/R8MAbXrZb3g