5.7 LS1/T56 swap for 305/5spd '89 C1500

[gl18rider]

Hi,
I've been scouring the pages at this site and hopefully absorbed a lot of the information. Thanks to all the contributors. I may have missed some as I still have some questions. It seems most are doing automatics? Has anyone done the T56 and have feedback?

The donor engine/trans/PCM (whole enchilada) is from a 2000 Firebird (I haven't seen it). Things I've learned, and some questions:

Wiring harness: it should be with the LS1. Either hack it up, or aftermarket.
Engine mounts: after market adapter plates
Exhaust: use stock manifolds
Fuel pump: replace with Delco or Walpro. If the LS has single rail, use wix as regulator.
Gauges. Oil pressure- get adaptor for old sending unit. (S&P?)
Coolant temp - I've seen different responses. Some mention 3 wire sending unit, others indicate port on passenger side head and use old sending unit. Does the 3 wire sender work with later gauges and the '89? I'd prefer the 3 wire unit. Will it work?
PCM: Sorry, not completely clear here. It sounds like I remove the original and use the LS1 PCM and get it reprogramed. I haven't looked at the original PCM so I'm not sure of the number of connectors. Will these all be replaced by the LS harness or will there be some LS harness connections and some original connections? I don't quite get the merging of the harnesses.
Radiator: can I use the stock one with electric fans? I haven't seen any references to a part number for fans.
Oil pan: LS1 from Firebird?

Regarding the 5 speed (Getrag). Does anyone know if the VSS with it is compatible with the T56?

Can you please confirm my undstandings and hopefully answer some questions?
thanks for the help
-gl18rider

[92 6.0]

I didnt do a manual swap but as for some of your questions:
gauges: Yes get an adapter for the factory oil pressure gauge, and on the coolant temp when I first done my swap I used the 3 wire unit but was told it wasn't as accurate with the obs gauges so I tapped my water pump and put in the factory one for my truck. But my gauge reads the same as the 3 wire unit did.
Pcm: I removed my 92 ecm as its not needed. you only need the one for the ls1.
Radiator: Yes you can use your stock one. I swapped mine to 1 ton rad and installed the 05+ efans.
And the vss in the t56 is the only one you need you dont need the one out of the getrag. as the t56 one is going to be the right one for the pcm.
Hope this makes sense.

[low91]

Unless your on a tight budget I would use these instead of the stock manifolds.LS1 TRUCK - Schoenfeld Headers

I used the three wire sensor and it seemed to read right where it should besides factory gauges aren't that accurate to begin with. If you do use the three wire sensor method you can use the TPS sensor pigtail from your current TBI unit. Also one thing I don't like about the water pump taping method is that what if your water pump goes out and you don't have a way to tap the replacement right away? Gonna be running without knowing how hot your engine is for awhile.

[flattopwill]

Unless your on a tight budget I would use these instead of the stock manifolds.LS1 TRUCK - Schoenfeld Headers

Looks like you got your info straight. The old ecm can come out and go in the trash. I sold mine with the old motor.
For gauges, I recommend tapping the oil cooler block off plate for the oil pressure and using the obs sending unit. Get the coolant temp sensor adapter from S&P and put it in the passenger side head.

[gl18rider]

Thanks for the responses.
I think I'm good with the coolant and oil now.
What about the speedo?

[flattopwill]

Well, hopefully someone will correct me but It's a bit unclear with the 88-91 speedos cause they have the DRAC built into the gauge cluster and it's hard to access the wires. Here's how to do it on '92+ - http://www.ls1truck.com/forums/lsx-t...ol-wiring.html
If you just want it to work then just splice into the new vss wires and connect the old vss wires going to the cluster and it will work but is not tunable by the ECM for gear changes, tires sizes etc.

[tmjoki]

I am in the middle of the swap now on my 89 and i recommend getting the mounts that shift your engine back 1-2 inches. i bought the transdapt mount 4572 and the exhaust manifold on drivers side is so close to the rear brake lines the flange wont make it on. i am just going to weld and refab a second plate to my transdapt mounts.

[gl18rider]

I am in the middle of the swap now on my 89 and i recommend getting the mounts that shift your engine back 1-2 inches. i bought the transdapt mount 4572 and the exhaust manifold on drivers side is so close to the rear brake lines the flange wont make it on. i am just going to weld and refab a second plate to my transdapt mounts.

Can someone recommend which mount would provide the setback?

[low91]

Can someone recommend which mount would provide the setback?

Here ya go.
LS1 Conversion 1" Set Back Motor Mount Adapter Plates : eBay Motors (item 280500206464 end time May-29-10 23:07:35 PDT)

[gl18rider]

Thanks for the setback info and link. I did more research and talked to S&P. They had some interesting feedback. To start with, he thought the non-setback should work. He said it depended on the exhaust manifolds. TMJOKI, what year is the LS1 your putting in?
The other interesting approach he had was to keep the original computer for ABS, speedo, etc. I thought everyone was ditching their OBS PCM's and just using the new one? Is there any reason the new PCM would need the speedo if I have manual transmission? I thought I had a decent handle on the computer direction, but now I'm rethinking it.