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LTX and LSXPutting LT1s, LS1s, and their variants into Third Gens is becoming more popular. This board is for those who are doing and have done the swaps so they can discuss all of their technical aspects including repairs, swap info, and performance upgrades.
After frustration with my current LT1 swap and a long deployment to think, I decided to tear it apart and start over. I've started with ordering an LE2/LE3 HEADS/cam/intake package with voodoo rockers. I had Eric at victory racing build me a sportsman 383 bottom end that should run around 11.5:1. The motor is setup with all new plugs, sensors, wires, and a delco opti. I've also installed a psi wiring harness and returned the pcm to the passenger dash. My Pcm was tuned at pcmforless. I will be installing an electric water pump and an ATI balancer. I have a racetronix tpi fuel pump and custom fuel conversion lines from pure choice motorsports, dougs long tubes, madhammer mufflers, and summit cutouts (not stainless cause they were cheap so I may order different ones).
To move the tires I had my T-5 transmission built by Astro performance to their 485ftlb specs, I've redone the entire rear suspension except for my lowering springs with umi components. The front suspension is redone with new urethane bushings, all new moog steering components and a few other umi parts. The K member and lower A arms have been sand blasted and powder coated. I have single adjustable koni yellows on each corner and big brake upgrade ls1 brakes so I can retain the factory 16in wheels. the rear is a 9 bolt from an 89 ws6 with low miles and with 3.27 gears and posi.
There are a few items left to finish, however.
I have had several issues with the last swap that I do not want to carry over...
There was a lot of globby rust in the coolant system. How can I combat this? when I install the electric water pump with this in essence "rebuild" my existing pump or should I get a new one anyway? Also in pictures attached, ive discovered I was running coolant backward through my heater core because the thirdgen heater core lines are conveniently the exact opposite size of the 4th gen and fit right onto the water pump. My end goal is to have heat for the foggy winters here in WA. Ive viewed many threads on this swap and seen many people runningnit backward like this, if it is ok I will continue to run it this way. Also would the heater core produce the rust? Its new leaked and made heat fine when this was a tbi car.
Left is inlet, right is outlet. The hoses are the opposite the diameters of the LT1 pump.
All in a 2 car garage
1987 recaro KR seats
Old swap
Here are the heater hose diagrams if anyone could give me suggestions or can ok support me running the coolant through the core backward.
LT1 heater inlet is larger dia and matches 3rd gen heater outlet dia
Just to verify which is inlet and outlet. Mine started as tbi
I also need suggestions on power steering as my last setup had the lines rubbing on the balancer and I want it to look reasonably clean. I will order custom lines if needed.
Further im trying to decide on intake routing, I will likely need advice on hooking up the vacuum lines to the heating/vent system as well as the wiring that I stupidly cut out. I have an LT1 scanmaster on the way and have a cool plan for mounting it, and eventually a rearend rebuild with 3.70 gears. Ive swapped in a 140 Speedo and repaired a slightly cracked dash swapped in from a junkyard for $25. Plan is to strip and repaint/recarpet/ New weather stripping next summer. I'll post more and better photos of the entire process once its complete. Im open to questions about the swap including prices of my parts so dont hesitate to ask.
Any help or advice on my questions and my plans for the swap are much appriciated
Last edited by legend71; 03-13-2016 at 09:06 PM.
Reason: finished my install
Re: 383 VRE/LE2 LT1 swap. Almost ready to install.
That sounds like a really nice project and looks good! AFAIK, running the heater core in reverse flow will not hurt anything but will bring out the rust as you have experienced. It's basically back flushing your heater core! Before you hook up any coolant lines to the pump or radiator, run copious amounts of water through the heater core to "back flush" the heater core to get any remaining rust out of the system. Also, check your radiator as some of that rust may have found it's way into it as well, again run a copious amount of water through it to clean out the rust.
Looking at those coolant hose diagrams, it looks like GM took the easy (cheap) route and ran the coolant backwards through the heater core on the LT1 cars, probably due to the reverse cooling of the LT1. That should be enough confirmation that it's ok!
Re: 383 VRE/LE2 LT1 swap. Almost ready to install.
Bigal55, thanks for the help! That makes my life easier for the install. I will flush it out.
Fortunately I picked up a new becool LT1 radiator from a guy who switched project plans for $200 and after some drilling and cutting it fits nicely.
The swap is now complete and the car runs very well. It has about 500 miles on it and all the small bugs were initially worked out. I had to replace the O2 sensors and install the correct knock sensor and now my scanmaster is clear. I threw a 42 and 51 randomly the other day and the car would not restart. I disconnected the battery and that cleared the codes and now it runs fine again. It maintains 185 degs water temp and good oil px.
So far the Victory Racing 383 is awesome, no leaks, no weird sounds and it runs well. In combination with the Llyod Elliott heads/cam/intake it sounds amazing. My Astro Performance transmission is also very solid and smooth. The tune from PCMforless is spot on.
I still have a few issues I'm working on: I'd like to figure out where the 42/51 came from, also my vss is not working. I could bypass the computer and get the signal to the odometer and speedo like I did with the last LT1, but the computer needs the correct vss signal to run perfectly. I think I will try the dakota digital signal converter.
Continuing with the engine bay, the powder coated K member and lower A arms, all done at Skagit Powder Coating. Also here is one of my springs, i had to cut a coil off on both the front to get the stance I wanted, the LT1 is considerably lighter than the old truck 350 that i purchased the car with. If anyone can identify these or recommend a new set that will work with the lighter motor it would be appreciated.
Here is the Becool radiator install, picked this up off craigslist for $200 unused. Had to modify the radiator mount slightly as this is for a 4th gen. Also my wiring here is a PSI harness I got used. I modified the fuse block to suit my needs and tucked it up under the passenger side with the PCM. I chose not to tear the dash all apart and remove the excess wires that the harness replaced. Some I used for fused power to other items like the waterpump which comes on with key on power.
I did not like using the fender hole from the original wiring harness because it require me to stretch it too far and looked bad in the engine bay. I drilled a 2" hole below the ac delete box and ran the wiring through there into the under dash area. Also here are some of the water pump pictures.
The scanmaster is currently installed in the vent with double sided tape until I make a plastic mount. Here are pictures of the trans and mcleod clutch/flyweel. They are the street series for 550hp. There are some pictures of the prep before engine install like the steam tube, various bolts and accessory mounts, the delco opti, taylor wires, and ati balancer.
Finally, exhaust and the final product. The exhaust was done by Pacific Classics, I used Doug's thirdgen Headers and Madhammer mufflers. The mufflers are the same as GMMG uses. I used the air box from a v6 and the Hawks ram air scoops.
The clearance is not too bad, the car is really loud and the next goal for the motor is a dyno tune. I will be sanding and painting the car soon, and will replace the weather stripping. Eventually I will do a new interior with Recaro seat fabric to match my seats.
I like your build here. I'm slowly doing something very similar just using 24x 0411 pcm instead. How do you like the astro trans? Feel it was worth the money?
I like your build here. I'm slowly doing something very similar just using 24x 0411 pcm instead. How do you like the astro trans? Feel it was worth the money?
So far I do, in fact, the Astro Trans held up even after I ran the car without a pilot bushing, and the exhaust rattled the case to bell housing bolts half an inch out. I'm very lucky it was not damaged.
I chose Astro because they were really the easiest way to keep the five speed. Tony there is great at helping you choose what build is best for you. I had to send them my trans because they rarely have GM T5s on hand as they focus on mustangs.
Let me know how the 24x EFI works out, if my opti gives me any crap I'll will likely switch. I'm already on the second one for this build.
I have quite a few T-5's laying around, I don't plan on huge power numbers with mine and I have no real use for 2 overdrives so I thought about having Astro go thru one. Especially since you had a good experience with them.
I'll let you know on the 24x if I every get my project moving at a faster pace. I've collected tons of parts, just need work space and time. From information I've gathered over time it the crank sensor alignment is the worst part, past that it seem to work great.
Are you using GM opti modules? I've had more luck with old original modules than any current ones.
I have quite a few T-5's laying around, I don't plan on huge power numbers with mine and I have no real use for 2 overdrives so I thought about having Astro go thru one. Especially since you had a good experience with them.
I'll let you know on the 24x if I every get my project moving at a faster pace. I've collected tons of parts, just need work space and time. From information I've gathered over time it the crank sensor alignment is the worst part, past that it seem to work great.
Are you using GM opti modules? I've had more luck with old original modules than any current ones.
I am using AC Delco ones from summit which I thought were the same ones GM used. I think mine is failing again as I have no spark on cylinder #8 and its full of gas. Causing some narly rich conditions and backfiring. Im going to check the wires but I dont know what else it could be. To further complicate it, every so often it wont start, no crank, no noise, nothing.
AC Delco isn't what it used to be. The vintage factory ones always seem to be better than any new offering. If I had a spare old one I'd send it to you. And I don't think I had a opti problem that only concerned one cylinder, it was either working or not. But at higher rpm you could have a problem under the cap.
legend71, question about your vss fix, mentioned earlier. I have a 88 305 tpi car that Ive replaced with an lt1, running carb and msd distributor and box. trying to decide if I need ecu for the interior harness. VSS is biggest concern, saw you mentioned rewire to speedo/odo? can I bother you for details? If c207 is the connector it appears most of the wires are for the aldl system I don't need? Any help would be greatly appreciated.
Rollbuck
legend71, question about your vss fix, mentioned earlier. I have a 88 305 tpi car that Ive replaced with an lt1, running carb and msd distributor and box. trying to decide if I need ecu for the interior harness. VSS is biggest concern, saw you mentioned rewire to speedo/odo? can I bother you for details? If c207 is the connector it appears most of the wires are for the aldl system I don't need? Any help would be greatly appreciated.
Rollbuck
Rollbuck, if your goal is to make the speedo and odometer work then you should not need the ecu and everything necessary should be in the wiring that goes through the driver's side near the relays. I'll go through the wiring diagrams I have when I get home and let you know
AC Delco isn't what it used to be. The vintage factory ones always seem to be better than any new offering. If I had a spare old one I'd send it to you. And I don't think I had a opti problem that only concerned one cylinder, it was either working or not. But at higher rpm you could have a problem under the cap.
I discovered 2 burned through spark plug wires (LT1 diagnossis: step 1. always start by blaming the opti). I replaced them and now its running much better. Still rich from the lack of vss signal telling the computer to quit fueling during deceleration.
legend71, question about your vss fix, mentioned earlier. I have a 88 305 tpi car that Ive replaced with an lt1, running carb and msd distributor and box. trying to decide if I need ecu for the interior harness. VSS is biggest concern, saw you mentioned rewire to speedo/odo? can I bother you for details? If c207 is the connector it appears most of the wires are for the aldl system I don't need? Any help would be greatly appreciated.
Rollbuck
Rollbuck, I looked into your year of car. It seems that you have a vss buffer box similar to mine. The purple and yellow wires take the signal from the trans then goes through c100 to the bufferbox. From there a red wire takes the vss signal to the instrument cluster through c207. Provided you do not remove any wires to the buffer box, it should all work fine.
Since youre running a carb you shouldnt need any of the services from the pcm for the LT1. I would just verify you dont need anything else controlled by the old tpi ecu. I more or less failed at a tpi swap a couple of years ago.
Also can you tell me what you used to convert your LT1 to carb? I have another LT1 in my garage and I was thinking of building it that way to learn how to rebuild it, and how carbs work
Here are the pin outs for your ecu so you can double check.
http://chevythunder.com/fuel%20injection%20ecm%20pinouts.htm#1986-89 pinouts (ecm #1227165)
Long story short. I got a deal on a 91 camaro being set up for drag. Motor was complete, gm intake with edelbrock thumper carb, msd distributor and box, with trick flow heads. Mechanic friend took it in trade for work. Motor was nice, but rest of project unfinished.ie trans torque arm had been bolted to rear end by drilling hole in rear housing and using spacers. (pretty sure they never launched hard). Friend sold me mess for the price of one of the heads. My ta had 305 tpi but set for 8 years after 305 freshup. Stripped car and started. Just want nice car for riding, making it my way...lol
The swap is getting closer and closer to 100%. The alternator recently went bad and two warranties later (dont buy orileys Ultima brand, lifetime or not) the car is charging like normal. I installed dakota digital's SGI-5E speed signal converter and with the #7 install instructions set on L-H with a ratio of 675 I was able to get a correct reading in the computer for speed. I have not reset the computer yet so it is still throwing a dtc-91 and Im hoping after it will clear and my fuel mapping will finally be correct. The car is still backfiring profusely under acceleration and that is the main issue Im hoping to fix. If having correct vss doesnt fix this Im not sure where to go next, injectors? More open air intake? Any suggestions would help. Below is how I wired the SGI:
Are you still running that mail order tune from PCMforless? Long ago I had a PROM burned from there due to I was expecting to have problems with a factory tune since I was swapping in a warmed up and larger injector engine and a manual instead of automatic. Turns out it ran poorly, and gave me a vss code with the mail order tune. I swapped in the factory PROM and it ran pretty good with no codes. It was well enough to drive to a dyno tune session while the mail order was not. Not saying this is your problem but I wouldn't rely on it if it were me.
So it's been awhile since I posted about my 91 Camaro but I'm hoping someone will have a few ideas about this.
Ive gotten the VRE 383 LT1 running an seemingly working pretty well. The car pulls hard and I only have the shift skip code.
Recently the the motor has started spewing oil out of the dipstick holder at the block at 4500+ rpm. It has ruined one starter and has made an absolute mess of my headers. The motor also developed split blins and a stumble like a vaccine leak. A local shop the vacuum leak in the PCV grommet and replaced it as well as sealed the dipstick holder. The motor runs great again but at the same rpm it started spewing oil in the same spot. My headers are caked an I assume their appearance is ruined. I'm wondering we're the pressure is coming from and how to stop it. I currently have a 94 PCV setup and not sure if 95+ is better or if it matters. Not sure the year of the intake but it has the vacuum port on both the front and side.
I have a 94 style PCV system. The drivers side of the intake houses the PCV and a little 180 deg loop of hose to a vacuum port about 2 inches away. The passenger valve cover has the stock crankcase vent which is a plastic elbow that runs to a port on the throttle body to draw in MAF measured air.
I know the PCV on a 95 is in the same place but uses a vacuum port on the forward part of the intake below the throttle body. I could reconfigure it this way if it's better.
Sure looks cool. I'd hate to think it but did you do a leak down test? It's possible those rings didn't seat right or a ring broke maybe? I've ran into it myself on a gen 1 350.
Edit: I wanted to add something about the pcv system but I'm not exactly sure I have anything good to add lol. I wanted to improve somehow on mine but went back to stock. Maybe run it backwards, supply fresh air to the driver side port to the galley and run a vac line to the driver side valve cover? Not sure, but either way I would use clear tubing to ensure nothing nefarious is taking place.
Backfiring: what plugs? octane? Maybe fuel isn't keeping up with air supply. Look up the injector pulse duration vs what the injectors are rated for vs pressure at the rail.
Amazing build btw, I'll be interested to see what ends up solving the oil issues.
My catch can system that still isn't really helping...
Are you sure the PCV valve is functional? Do you have a blocking valve in the lines that is installed backwards?
You need to create air flow from atmospheric to low pressure (vacuum) in the intake manifold. Ideally you want to create a cross-flow from one side of engine to the other and pull the vapors into the catch can just before the vapors go into the intake manifold.
PCV is installed as stock for 95 LT1 minus the line from valve cover to the throttle body. I replaced that with the catch can lines out of both covers to the can per the instructions of two separate builders.
Couple things have happened with the car. The drivers side head developed a pinhole between the exhaust port and a coolant passage. The heads were removed by a local shop and fortunately no coolant got into the block. Contacted Lloyd Elliott for new heads and I went with the 21 deg trickflow heads with 54cc chambers and a port and valve job. These are now installed and I had the 9bolt rebuilt with 3.70 gears from strange. The oil problems seem to be gone now that everything is tightened down so that's great.
I've been able to drive the car a bit and there are still a few issues with excess heat on the right side of the exhaust and rattling which may be the exhaust contacting the trans mount. Waiting on a local tuner to contact me but should able to get the most out of the new heads.
10-14-2015, 04:38 PM
