Just finished swapping an LT1/T56 from a 96 Camaro SS into my 1986 Iroc (previously 305/T5 car). I have tinkered with cars and ag equipment all my life and have a fair amount of industrial controls/electrical experience but this was my first time attempting something this major both mechanically and electrically. I have been working on it off and on for about 3-4 months and started/drove it for the first time last weekend. I could not have done it without all the info posted on thirdgen.org I was very **** about the wiring but still couldnt believe it started on the first crank without any problems. Most of this is already posted elsewhere but here is what I found did and did not work along with some part numbers that I hope somebody finds useful.

POWER STEERING LINES
*reservoir to pump - 5/8" ID low pressure hose with worm gear clamps
*pump to steering gear - HP line from 1995 Impala, bought at O'Reilly, Powercraft P/N 91780, installed with little to no modifications, just had to remove the old pressure switch 90deg tube from the gear
*gear to reservoir return line - 3/8" ID low pressure hose with worm gear clamps

RADIATOR HOSES (KEPT MY OLD 86 RADIATOR AND FAN FOR NOW)
*upper hose - from 95 Camaro Z28, it has to be the one with the extra 3/8" hose tee'd in to connect the throttle body, Gates P/N 22046 from O'Reilly, fit without modification
*lower hose - from 94 Corvette, Gates P/N 22464 from O'Reilly, I cut some length off the bottom of the hose but should have took off more than I did, the upper section of the hose was rubbing against my power steering pump pulley which I didn't realize until I had already filled the radiator, tied it back for now but will need to drain the radiator and cut some more length off the bottom
*heater hoses - 5/8" and 3/4" ID
*my water pump had a connection for the transmission cooler which I don't have so I just used a short hose and plugged it with a bolt and hose clamp for now, plan to figure something else out because it is ugly
*haven't pushed the car too hard yet but so far engine temp is looking good (A/C isn't operational so not a good test yet), I eventually want to switch to a dual fan setup

PCM TUNING
*used www.lt1swap.com for $75, he turned it around quick and I recommend his work
*disabled VATS, CAGS, rear HO2S
*disabled all emmisions diagnostics but kept everything functional since I have to pass a MO visual inspection to keep my tags

WIRING
*I highly recommend buying GM service manuals for both the car you are working on and the donor car and if you can't read wiring schematics you need to learn, it is pretty straight forward if you study up but if you're just hooking wire A to wire B because somebody on a message board said so good luck on troubleshooting it later if something doesn't work and you don't understand what you did in the first place, be careful when buying the 3rd gen manuals because not all of them have detailed wiring diagrams, apparently there is a difference between "shop manual" and "service manual" and some are missing section 8 which is about the only section you need
*extended all PCM wiring so I could mount it in the original 86' location, right now it is laying on my passenger floorboards but it looks like it will fit
*I assembled my own underhood fuse/relay block but IMO it doesn't look clean and I will probably buy a used 4th gen fuse/relay block and use it, if you are buying a motor from a donor car ask them to throw this in

TRANSMISSION/CLUTCH
*kept my 3rd gen pedals and bought a new 4th gen master/slave cylinder assembly from rockauto.com, Sachs P/N SPH002, dimensionally it was a perfect fit after I drilled out the plastic bushing from the master rod and used my old plastic retainer bushing, however it disengages somewhat high and if you push the pedal to the floor the clutch chatters like it is rubbing on something internally, the high engagement does not bother me but I will have to fix the "over disengagement" either by shortening the master cylinder rod or adding a mechanical stop to my pedal, I also have a set of 4th gen pedals I could put in
*used a Spohn 3rd gen T56 swap crossmember that was a direct bolt in, also bought subframe connectors but haven't welded them in yet
*kept original torque arm and used mounting bracket from old T5, didn't have to modify it at all, some guys say you have to shorten it a couple inches but in my case it was a bolt together deal
*installed new Ram clutch, no problems or gripes so far

MOTOR
*against all my friends advice, I bought an LT1/T56 combo on eBay for $2000 and didn't rebuild it, just pulled the oil pan and valve covers for inspection and slapped it in. . . probably just got lucky that it ran
*replaced valve cover gaskets, oil pan gasket, water pump, thermostat, rear main seal, timing cover gasket/seals
*the old 305 motor mounts bolt right on to the LT1 block, not the case with an LS1 from what I understand
*some guys say an LT1 is a tight fit in a 3rd gen but in my case it fit just as easily as the old 305, no oil pan clearance issues or anything

A/C
*notched the passenger side of the k-member and welded in a piece of 1/4" angle iron and also had to modify the passenger side motor mount, the compressor fits with almost zero clearance so make sure you take enough off the k-member
*plan to use computer controlled A/C but not a real high priority for me at the moment
*does anyone know if I can keep the original condensor and evaporator or do I have to swap one or the other going to R-134a?

FUEL SYSTEM
*ran all new AN hose/fittings from tank to rails, I can get you my parts list but I'll tell you up front it isn't going to be cheap
*new inline Walbro 255 lph pump w/ AN adaptors, the noise isn't horrible but if I ever have to drop my tank I'll install an in-tank unit

EXHAUST
*kept LT1 exhaust manifolds and taking it to the shop tomorrow to have them fabricate/install a y-pipe and Magnaflow cat, keeping the aftermarket cat-back system PO installed for now (he wasn't in an inspection state and had also removed the cat), should probably install new headers but don't want to spend the money

PROBLEMS
*The only major problem I have found so far is oil pressure, once the motor gets up to temp oil pressure is very low at idle, I just bought a mechanical gauge so I know for sure, I am using the LT1 sendor and original 3rd gen gauge, does anyone know if the gauge reading should be accurate with this setup or have an ohms vs. pressure chart for both the 3rd gen and 4th gen sendors
*Reverse lockout solenoid opens up anytime the key is on so I hosed up the wiring somewhere, I just need to wire it to the brake pedal switch or something but not a show stopper, I might just unplug it because you can still force it against the spring into reverse without too much force
*Char cannister plumbing, I'm sure it isnt complicated but I just haven't dug into it yet
*Don't have a good plan for the air intake, right now it is just a K&N filter clamped to the MAF sensor, if I can figure a way to relocate the char cannister I want to put in a 4th gen aftermarket cold air intake

Again, thanks for everyone that posts information on this website and I hope someone finds my (first) post useful. Feel free to ask me any questions you have and I will try to answer.

 

Well you said you used a mechanical oil pressure gauge? The electronic sender is either accurate to that or not....?

 

Great info. thanks. When the y-pipe is done, post some pics if you can. I am going to try and make my own out of a 3rd and 4th gen y-pipe. Any motor pics?

 

I should have clarified that I bought a mechanical pressure gauge but haven't hooked it up yet and won't be able to until tomorrow or Thursday, obviously that will tell me what I need to know but I was wondering if the 4th gen sender and 3rd gen gauge are truly 100% compatable or if you have to wire in a resistor or something to get the gauge to read correctly. In other words do the 3rd gen and 4th gen senders have the same electrical output range across the actual oil pressure range?

 

Having the same exact issue with my car, but I mildly rebuilt mine with all new gaskets, high volume oil pump, timing chain, ect. Anything that was 10 times easier to do with it out than in I did, and having the same exact issue as above, but mine actually got rediculously low after a 45 minute drive last night, so afraid to use it. Going to try and mechanical gauge mine in a little while, but subscribing to this as I'd like to know as well if they are 100% compatable.

 

I hooked up a manual gauge and started the engine (it was still warm from driving it about an hour earlier) and got 25 psi at idle and 50 psi at 2k RPM (if I trust the tach which I still need to verify with a stroboscope). As the motor warmed up to temp my idle pressure dropped to 12-13 psi but it was still close to 50 at 2k RPM. I shut it down and put the sender back in and got less than 5 psi at idle and a little under 30 at 2k RPM, based on this it looks like the 4th gen sender/3rd gen gauge setup is not accurate and will read low but I haven't hear of anyone else having this problem. I am going to try to find some fittings to use both the manual and electronic gauges at the same time so I can watch them both while driving.

My GM service manual spec's 20-60 psi as "normal oil pressure" and it shouldn't drop below 4 psi at idle. Based on this, 12-13 at warm idle may be normal for a used motor that hasn't been rebuilt.

84 - let me know what you get with your mechanical gauge compared to you electronic gauge. I haven't had any luck finding ohms vs. pressure specs for the different senders, If I can find my old 3rd gen sender I will test them both with my Mityvac pump and post it on here.

 

For the AC-
If I can remember correctly, it can run without being computer controlled. When I had the bower's bracket and AC working back in 2006, I had really only the sensor that is on the aluminum acculator(aka evaporater?) control when the compressor cycled on/off. I may have used a relay in conjunction with the sensor. I'm working on building AC lines for thirdgen condensor and f-body LT1 compressor right now so its halfway fresh in my mind. It will be more clear when I hopefully wire it all up again soon before it gets really warm out.

I'm not sure what benefit there would be from having it computer controlled anyway. I don't think it will automatically shut off the AC when you mash on the throttle like 2003-ish and up Mustangs do.

Also, a variable orifice tube is supposed to make a R134a system make interior temps about 10 degrees cooler or at the least be a notable difference.

 

12-13 PSI is more then enough. You will not have any problems. One of my 4TH gen's with 32k on it only has 15.

 

That's what my LT1 had with 150k miles on it, after rebuilding the engine and putting a stock oil pump back in, it holds about 20-25 at idle after a 26 mile drive and about 50 driving down the road. I have verified my tach with my scan program and it is dead on, but then again this is in a GTA (old L98 car) instead of a Camaro (I've read people have had problems with Camaro tachs in the past even with the stock 305s in it)

 

ive heard this from more than 1 person including my brothers 93 Z28 with 90k on it always reads real low too but has never had any problems with it.

 

Well sometimes the most likely answer is also the correct one, I picked up two new sensors one for an 86' 305 and one for the 96' LT1 and measured resistance from 0-30 psig from a hand pump and both were pretty close or at least close enough that it should work. I checked the sender on the motor and it was way off so I had a bad sender all along which I didn't consider because it was brand new when I put in the motor, must have been bad in the box. Anyway with the new sender I am getting around 15 psig at warm idle which is close to what I get with a mechanical gauge.

Chart and graph attached if anyone is interested in what ohm readings you should get at different pressures.