3500 swap questions

[LeftVentricle]

Swapping an LX9 into a 1996 A-body (Buick Century, Oldsmobile Cutlass Ciera).

These notes apply only to the 1996 model year. 1994 and 1995 are transition years with regards to the computer systems ("OBD 1.5"), and most of the things I do will not work in 94 or 95 cars. If you wish to swap an LX9 into one of those cars, you should probably do a complete OBD2 wiring and computer swap, and go from there, or just buy a '96 V6 car. Hell, you could probably do this in a '96 van if you wanted, but without having to deal with all the throttle body/cable bullshit I had to handle.

As an aside, a lot of the things I did were aimed toward keeping a stock or "sleeper" appearance. If you don't care about keeping it looking stock, you can change it up however you want. The county I live in does emissions testing, so I have to keep it "stock".

To start with, you will need some custom parts.
-External crank trigger for the 7x sensor, as you would for swapping the LX9 into any other car. Take your stock 7x sensor out of the L82 (or buy a new one) and put it into the trigger bracket. Leave the LX9 sensor in the block to prevent a massive oil leak.
-(Alternatively, tear the crank out of both the L82 and LX9 and install the L82's internal reluctor wheel onto the LX9 crank in the exact same position and orientation. Good luck.)
-The stock computer may run this engine, but it probably won't run well. I ordered a retuned, repinned '97 Monte Carlo PCM from Milzy, since, until recently, WOT-Tech didn't offer a '96 upgrade.
-Differential bracket. The stock A-body bracket does not bolt on to the LX9 block. I bought one from Milzy Motorsports, since to my knowledge WOT-Tech does not offer one.
-Cam postition sensor. I believe this is a 2000-2003 sensor, but again, I bought it from Milzy, since he offers it with the correct wiring to plug into the stock A-body harness.
-Not custom, but you'll need to transfer your L82 crank pulley and 24x sensor over to the LX9.
-Wiring extension for the coolant temperature sensor. The LX9 has the CTS in the rear head, rather than in the thermostat housing portion of the lower intake. This is dependant on whether your car has a two wire or three wire sensor. There doesn't seem to be a rhyme or reason on these cars as to which one they will have. I have seen a couple '96 cars in the yard with a two wire sensor. For the record, mine has a three wire. Again, I bought an extension from Milzy, but, despite it being an option on his site, he no longer offers a three wire extension. I had to splice in a few extra inches with a connector I clipped off at the yard. This proved more difficult than I anticipated, since, as I said, there didn't seem to be a pattern to which cars (across various platforms) had a three wire sensor.
-Remove the LX9's coolant sensor and install the three wire one Milzy includes in his kit. Put teflon tape on the threads. Use a deep 19 mm socket. Don't hammer it in. It's an aluminum head. Just snug.
-Dogbone. A and W cars used dogbones, others did not. The stock A-body dogbone will not bolt on to the LX9 block. You'll have to use a later W-body one. Again, I bought one from Milzy. You'll also need to replace the head bolt that goes under the bracket, since cars with dogbones have a head bolt there with either a taller head or a stud that you bolt the bracket on to. It is safe to remove the one bolt. Torque is 44 ft-lbs + 95 degrees.

Moving on from custom parts. This is all just raiding the parts bin, or playing GM Legos, if you will.
-Throttle body is not really "custom", but the stock A-body one is unuseable, unless you make yourself an adapter. It uses three studs around the throttle opening, instead of the two (other L82, LG8, LA1) or four (LX9) bolts other engines use. No one makes one commercially. Someone on the A-body board made one for themselves a few years back when they did a big port swap on their '94 Ciera, but they only made one and didn't post any dimensions or schematics for the benefit of the board at large. You will need to use a throttle body from a non-A-body car. Size is really the only deciding factor. Since the mentality is generally "go big or go home", an LA1 TB is probably in order.
-The other reason the A-body L82 TB is unuseable is the throttle cable and linkage. It is "Buick-style", meaning it is very similar to the one used on older 3.8 and 3.3 Buick engines. Why GM chose to engineer a bespoke throttle body and upper intake manifold for the A cars when literally millions of other L82-powered vehicles had new stuff is beyond me. The linkage is on the "wrong" side (facing the firewall) and uses some ball pivot nonsense which is wholly incompatible. You can't even just swap the linkage over, since the throttle return spring is separate, not integrated, and would be on the wrong side anyway. You can't use any of the stock sensors either. Unbolt it, clip the cables, toss the whole thing in the bin.
-Take this opportunity to get rid of the "black box". It's a plastic housing mounted to the firewall right next to the AC drier. The throttle and cruise cables go in here for whatever reason. Since you're not using the stock TB, this box can go right in the bin with the stock TB.
-You'll need a cable bracket from some other L82/LG8/LA1 car, since the stock one doesn't work for a variety of other, but related, reasons.
-The throttle cable... Most A-body folks reasoned that you'll need a cable from a 1996 van, which is a perfect storm of NLA. First, it's one year only, being the last year of the A-body-based U platform, and the only year an LA1 was available. The cable is NLA from GM, and not made aftermarket. So few '96s were made that you probably won't find one in a junkyard. I've only personally ever seen one in the last five years or so, and it was well before undertaking this swap. But really, since you're using a new TB, just get a cable from any old thing. I settled on a '97 Lumina, but it's stupid long for some reason. I will probably try and find a shorter one at a later date, but it works for now. The only other issue is the firewall connector. The A-body is square, and the Lumina is round. You'll need to "massage" the opening a bit, but it clips on to the pedal just like stock.
-I had a hard time coming up with a solution for maintaining cruise control. The A-body's cable clips in to the cruise module with a square clip, much like the throttle cable going in to the firewall. Every other GM car with electronic cruise, from four cylinders, to other Chevy V6s, to Buick V6s, to Northstars, use a round twist-lock clip. I couldn't figure out a non-redneck way to make it work, aside fron cutting the actual Lumina cable and putting it in the A-body housing in some way. I don't own any metal melting equipment though, and the only mechanical solution I tried (Dorman 03336 cable clamps) was a bust, I just shaved the clips off the outside of the round part, hooked the ribbon from the inside of the module up to the cable, and let it sit there, free. The cruise works. It takes a lot longer than before to engage, losing around 3-4 mph on the highway before it grabs, but it works. That's what mattered to me.
-I also considered using a cruise module from another car to match the Lumina cable, but again, the A-body bites me in the ass. The modules all share the same ten pin electrical connector, but the A-body only uses nine wires. At the time, I didn't want to take the chance of potentially wasting my money on a cruise module if it didn't work. I may revisit this in the future.
-Throttle position sensor wiring: it will need to have a "new-style" connector spliced on, or repinned onto a new connector. The "old" wires are all the same color as the "new" ones.
-Idle speed control : the part itself is a slightly different design, but the electrical connector is the same.
-The mass air flow sensor is totally different. Going back to being "Buick-style", the sensor is sort of integrated into the throttle body, while the later ones are in the intake hose assembly somewhere. The connector is the same between the two. You can then use a stock MAF sensor and housing from pretty much any 1996-2005 Chevy V6.
-Intake air temperature sensor is shared. No modifications necessary. Just jam it in there any old place.
-Toss the LX9 fuel rail and injectors in the corner. The LX9's fuel system is returnless. Not compatible. Use your stock rail and regulator. It will line up and bolt down in the stock position.
-Fuel injectors are sort of a toss-up. You shouldn't use the stock injectors, since they are only 19 pounds. You'll pretty much max them out on a bone stock engine. I went with L67 injectors, which are known as having a flow rate of 36 pounds. Your stock computer definitely won't run those correctly. Once again, Milzy got me these, along with modified fuel rail brackets. You'll need slightly longer bolts to put the rail back in. M6 x 1.0 x 16 is what I used. The stock ones are 10 mm, and are too short.
-The L67 injectors have to be modified a bit. The body length and wiring are the same as stock, but there is a groove where the retaining clips ride that is partially missing on the L67s. I imagine this is because of the different mounting position of the L67 rail on its engine. That groove needs to be added. A quick hit with a band saw was all I needed.
-Beyond that, the engine itself drops back in place without issue, since the block is physically the same size, and it has the same bellhousing as your stock engine/transmission. It will use stock mounts no problem. You'll need to transfer over your passenger side engine mount bracket, the one that goes under the crank pulley. The LX9 I bought came out of a Malibu, which uses a mount that bolts to the wheel well, like a C-body. The bracket bolts on just like stock.
-Some engines may have a plate of some sort on the timing cover. It's just basically glued on. It'll have to come off so you can mount your stock accessories.
-Speaking of accessories: your stock tensioner, power steering pump and alternator bolt on in their stock positions without issue. You'll need to transfer over your alternator bracket and passenger side engine lift bracket. The engine lift bracket spaces the alternator bracket out a bit to line up with the belt. The LX9's lift bracket is stamped differently, and doesn't fit behind the L82 alternator bracket.
-Unless it makes some noise when you spin it, don't do anything with the water pump. It's fine. Lets you keep your stock lower radiator hose.
-The air conditioning compressor, however, is a different story. As I said above, the dogbone bracket will need to be changed. This leaves nowhere to mount your stock compressor, since the stock one bolts to the dogbone bracket, while the LX9 has it bolted directly to the block. A 94-98 V6 N-body (not Malibu or Cutlass though) compressor is the solution, because it bolts to the block in the same way, and has the refrigerant hoses in the same orientation as your stock compressor. That or bolt on a bypass pulley (Dorman 34127). Either way, make sure you evacuate the AC system beforehand so you're not illegaly venting nasty shit to atmosphere.
-No matter what you choose, your stock belt is now too long, by one inch. Stock is 69.5". Buy one at 68.5". If you must specify an application, same as the compressor: any 94-98 N-body V6, aside from the Malibu and Cutlass.
-Transfer your oil pressure sender from the L82 to the LX9 (or install a new one for the L82). The LX9 is a single wire sender, the L82 has a three wire.
-Transfer your stock knock sensor over as well.
-As stated above, I chose to maintain a stock engine appearance. I used an LG8 upper intake manifold, from a 2001 Pontiac Grand Prix. In addition to looking stock to anyone uninformed about the L82's ribbed UIM, it allows me to retain vacuum for my HVAC, manifold absolute pressure sensor (MAP), and transmission modulator for the stock 4T60E.
-I also used my stock exhaust. The front and rear manifolds bolt on to the LX9 heads in the same place.
-Your stock EGR valve will not mount to the LG8 upper. You also will not be able to use the one from the LX9. You'll need one from an LG8 or LA1, along with the stove pipe. The pipe will screw in to the stock rear manifold the same. Make sure the connector on the valve is the same as your stock one. Most of the vertical-mount ones are, but some have these weird grooves in them, while my stock connector was smooth.
-When you bolt the valve on to the intake, the bolt on the left (when standing in the front of the car), will touch the stock L82 fuel line when cranked down fully. I'm not sure of the pitch, but just take it to a hardware store and have them give you one 10 mm shorter. You don't need that bolt to wear a hole in your fuel line.
-Transfer over your stock EVAP solenoid(s). It (they) will bolt on in the stock position. I used supposed plurals because California cars (which mine is) have two solenoids there: one blocky one, one disc-shaped one. I think on non-CA cars one of them is instead mounted onto the charcoal canister. I'm not really sure.
-Your stock starter will bolt on and wire up like stock, assuming you want to keep the stock starter. You can use a newer-style small starter from an LG8/LA1 if you want, which will likewise go on like stock. Going with my sleeper status, I used my stock starter, so it sounds stock.
-Since I used an LG8 upper, I can also mount my stock igntion module and coils in the stock position.
-My LX9 came with the heater pipe on top of the water pump from the Malibu. Doesn't work in an A-body. Transfer your stock one over. This allows you to use your stock heater core hoses. Despite the fact that neither the LX9 nor the L82 used a gasket there, and the L82 didn't leak before, when I ran the L82 heater pipe on the LX9, it leaked from there. Couldn't hurt to slap some water pump gasket maker (grey RTV) on there. You have to let it cure for 24 hours though.
-Some folk say you need to transfer your L82 water fitting over to the LX9. This is the one that comes out of the thermostat housing area of the lower intake manifold, under the throttle body. This would necessitate removing the LX9's hose and tapping the boss 1/2" NPT to use the L82 pipe. I didn't do that. I just clamped the heater core hose on and called it a day.
-Transfer your stock thermostat housing over. Lets you keep your stock upper radiator hose.
-Using an LA1 throttle body, L82 thermostat housing, LX9 water fitting, and an A-body heater pipe, there is nowhere for the throttle body heater to accept its coolant.
-Oh well.
-Seriously, you don't need a TB heater. Don't bother. Don't even need to cap the pipes off on the TB.
-Again with the stock appearance: Put your stock air cleaner back in place. Details below.
-The MAF sensor you will need to use does not mount in the stock location (in the throttle body). You'll need to put the body somewhere in the air stream. LG8/LA1 cars put it in the intake hose, in between the TB and the air cleaner. This is where I put mine. Using the stock air cleaner, I went air cleaner -> stock intake hose (IAT goes here as well) -> MAF. In order to join the MAF and the TB, I bought a 3" to 3-1/4" silicone coupler, in black. 3" goes on the TB, 3-1/4" on the MAF. Use a standard worm gear clamp on the TB side. I used a T-bolt on the MAF side. You don't have to, but it's a little more secure, I guess.
-This will compress your stock air hose a bit. It's accordion-like, so it should be okay. If it is cracked, look in to getting a new one. It's part number 25147228, but good luck getting one from a dealer. A junkyard part will probably be in the same or worse shape. I lucked out. Mine is okay. Otherwise you'll have to run some stupid ricey aluminum thing.
-Everything else is just tightening down bolts and clipping the harness back in to everything. The LX9 will mate with your stock torque converter and transmission without issue.
-I might recommend replacing your converter while you have it apart. Part number GM42CW is a good one I've been using for a couple years without issue. Available from a few companies; I bought a ProKing. 245 mm, carbon clutch, 1800-2200 stall. Locked up nice and tight while towing a 5x8 U-Haul trailer at 60 mph in third gear for 1200 miles.
-I also replaced the converter or input shaft seal, but if it doesn't already leak, leave it alone. It'll probably be fine.
-Also going to recommend an adjustable vacuum modulator. Nobody really makes one specifically for a 4T60(E). Specify one for a TH400. It should be a brass color with two red stripes.
-Last thing: The LX9 uses a remote oil filter housing. It appears that it would interfere with either the radiator fan and/or the subframe when mounted in an A-body. I removed it, and installed the threaded dealy that the filter spins on to from the L82. You'll need a 10 mm internal hex (or "allen") socket.


Good start for an article? Anybody who is an editor, feel free to critique my writing.

EDIT 11-23-2016: The MAF wiring does not need to be modified. Text above has been edited to reflect this.

[2000GAGT]

wow this is a long thread! I would just like to say I swapped in a 3500 LX9 to my 2000 grand am gt about two years ago and have put 37,000 miles on it! Its running great besides the constant tuning I have with the supercharger installed but thats another story.

[buickboy]

Yea but the engine hasnt been well maintained at all and i just know the kind of guy the person is that i possibly will be buying it im buying it from and i would rather start with something fresh than keep that tired engine in there and i know it wont be a huge gain doing the swap but it would be a fun project that i think would be as fast as a l36 3800 would be if not a little bit quicker.

[RedBird]

if you're looking for a reliable daily driver for your lady-friend then you'd be better off maintaining that current 3100 or putting in another one of same. it's not really worth it to put the 3500 in unless you're specifically looking for a performance gain. personally, i'd throw in a set of metal lower intake gaskets and a *GM* timing chain set and call it good, even with 220K+ miles should run for a good while with those things taken care of.

[pocket-rocket]

Hey im new 2 this site i probrebly wont be on here alot but here is the deal i might be able to get ahold of a 1998 GP for $400 and its thrashed, but its a four door se green. The engine in it still runs good its the LG8 but it has 220,*** miles on it and Im wondering what it would take 2 swap the 3500 into it i dont want to go with a 3.8l because its normal and im the kind of guy who wants to be different and i like the 60 degree v6 better than the 90 degree design. but anyway what changes to the 3500 will have to be made to make it work? and about how much money would we be talking. i would probrbly be building the car for my GF to drivearound to work and back 2 so reliability is a factor as well.

Welcome to the site! You will find tons of information on this board that will help you along your 60 degree experience. I'm not sure what all is needed for a 3500 into a W body, but the information you want is in this thread, that's why it got stickied. Someone should probably go through this thread and corral all the info into 1 post so we could make it an article...

[buickboy]

Hey im new 2 this site i probrebly wont be on here alot but here is the deal i might be able to get ahold of a 1998 GP for $400 and its thrashed, but its a four door se green. The engine in it still runs good its the LG8 but it has 220,*** miles on it and Im wondering what it would take 2 swap the 3500 into it i dont want to go with a 3.8l because its normal and im the kind of guy who wants to be different and i like the 60 degree v6 better than the 90 degree design. but anyway what changes to the 3500 will have to be made to make it work? and about how much money would we be talking. i would probrbly be building the car for my GF to drivearound to work and back 2 so reliability is a factor as well.

[PCGUY112887]

I used a 3400 oil pan on my 3500 block. No issues with clearances at all. Ive turned the crank over by hand before putting it in the car and nothing hits. And yes 1 perimeter bolt hole is missing in the block. It could be tapped however I used the pan with 1 perimetor bolt missing. Probably not the best solutions, but I have no leaks. As for the lower engine to tranny mount. The solution is a mount that was made for the engine. As the G6 came with a 4t45e, the upper block to tranny mount is a perfect fit and the lower one from the 3400 that bolts to the oil pan lines up perfect as well. No Drilling whatsover needed.

[ATTACH=CONFIG]5181[/ATTACH][ATTACH=CONFIG]5182[/ATTACH]

Wow, it's been a while since i've logged in here and checked on this thread!

I'm glad to see you have a mount that works. That 4t45e mount that bolts to the engine perfectly, anyone know if the other half would bolt to a 4T60E?

[onefastV6]

He isn't the first that I have heard, that has used the 3400 pan on the 3500.
Personally, I am sticking with the 3500 pan.

[bszopi]

Well, good luck with it! Hopefully it works for a long time without incident!

[boomofdoom88]

yeah I've drove it 4 different days and until hot so I could bleed the air out of the coolant system.

[bszopi]

I used a 3400 oil pan on my 3500 block. No issues with clearances at all. Ive turned the crank over by hand before putting it in the car and nothing hits.

Have you started it yet? Once the engine gets going, things are going to start to stretch, and that's where you might run into issues. GM clearanced the block and pan for a reason...

[SappySE107]

Interesting. The block is notched and the pan is matched. I am surprised the stock 3500 connecting rods clear without the pan clearance.

[boomofdoom88]

You can not use a 3400 oil pan on a 3500 for multiple reasons, the main one being that the holes don't match up. The other being that the 3500 oil pan is clearances in several places for the connecting rods.

I think you have the crank sensors mixed up: 7x is the in-block one (which can not be used with the newer 3500 trigger, hence the WOT-Tech external), and the 24x is the one mounted on the timing cover.

Welcome to the site!!

I used a 3400 oil pan on my 3500 block. No issues with clearances at all. Ive turned the crank over by hand before putting it in the car and nothing hits. And yes 1 perimeter bolt hole is missing in the block. It could be tapped however I used the pan with 1 perimetor bolt missing. Probably not the best solutions, but I have no leaks. As for the lower engine to tranny mount. The solution is a mount that was made for the engine. As the G6 came with a 4t45e, the upper block to tranny mount is a perfect fit and the lower one from the 3400 that bolts to the oil pan lines up perfect as well. No Drilling whatsover needed.

[bszopi]

i will use 3500 mounts but use the 3400 oil pan to retain my sensor the 3500 lacks.

Get a WOT tech external crank trigger to solve the 24x sensor. Swap over the arched 7x sensor from my 3400.

You can not use a 3400 oil pan on a 3500 for multiple reasons, the main one being that the holes don't match up. The other being that the 3500 oil pan is clearances in several places for the connecting rods.

I think you have the crank sensors mixed up: 7x is the in-block one (which can not be used with the newer 3500 trigger, hence the WOT-Tech external), and the 24x is the one mounted on the timing cover.

Welcome to the site!!

[elementdrummer]

There is a TON of information on a bunch of different cars for this swap. Its hard to find the right pages or my 1999 grand am 3400 to 3500 swap i have started.

Basically heres where I stand, hopefully someone will correct me if I am wrong.

Using 3400 plenum with 3400 gaskets will be port and polished for better flow. This will retain the grand am TB which will be upgraded to 62 or 65mm throttle body.

Using 2000+ 22lb injectors as well as 2000+ FPR and my origional 1999 3400 fuel rails along with new plugs and wires for my 3400.

Using all of 3400 accessories including ignition control module and coil packs. No major issues mounting up besides a/c not having 1 bolt hole it seems.

Will be missing 1 bolt for tranny to engine mount unless I customize. i will use 3500 mounts but use the 3400 oil pan to retain my sensor the 3500 lacks.

Get a WOT tech external crank trigger to solve the 24x sensor. Swap over the arched 7x sensor from my 3400.

I believe most of the other sensors will work so i will leave them in he 3500, may have to do some wiring, but its all the same signals.

Since i am a 99 grand am i will swap my cam sensor over to the 3500.

Which is best to use for rebuild 3400 metal gaskets? or factory 3500 gaskets or is there a felpro that will work? I may do a cam and port and polish the heads as well.
Use 3400 exhaust manifold. hopeully try to score some S&S headers but that is unlikely... may just have to use stock thats my only other option it seems.

Will flatbed car to shop to get a custome tune.

Need some expirience to reply back, will be getting new motor this month, I want to be part of this awesome 3500 swap group haha