I've been swapping a 4.8L iron block into my GTO. I have the motor in the engine bay and the 4L65e trans lined up but I can't seem to get the pin to line up.

I have all the accessories to hook up to the motor afterwards. I would just like someone experienced help getting the trans linked to the engine, and the harness and everything to match up so I can get this car running by end of week, preferably before Thursday. I have two wiring harnesses (LS2 and 4.8) so we can do some hacking up of them if needed.

If anyone has any experience and thinks they can help me, I'd be willing to throw a couple hundred bucks your way. For the most part the heavy lifting has been done. If you have experience with this swap then it should be pretty simple and some easy cash.

This is my first swap with this motor, and my buddy that was helping, unfortunately, had to have back surgery and can not assist any further for anything other than looking things over.

Thanks for any assistance.

 

Are you having trouble getting the trans on the dial pins?
try removing the torque converter and try it..

did you use the GTO LS2 flexplate on the 4.8?

 

I swapped the LS2 flex plate onto the 4.8, yes. I measured the clearance between the two blocks and their flexplates and the LS2 looks like it was a direct swap onto the 4.8 in order to link up to the 4L65e. The 4.8/6.0 crank length were the same.

I did not try removing the torque converter. Maybe that would help.

Do you by any chance know where I can get info on what to do with the harness? The knock sensors on the 4.8L are in the valley covers and share a split wire, whereas the LS2 had two separate wires.

Thanks

 

You still have the LS2 KS connectors/harness?
Could use the LS2 wiring and solder on the 4.8 Knock sensor wires?


The LS2 harness wont work?

 

I'll have to use the ls2 harness for sure because it has the drive by wire throttle body. I can use the knock sensor, no problem, but I'll have one extra. Would that bean issue or should I just pigtail it to nothing?

The other issue is the oil pressure sensor on the rear of the iron block has a different connection than the aluminum block (if I recall.) I'll have to look again. If so, I have the 4.8 harness to hack up and solder on.

That should be it, correct? All the other accessories that were on my aluminum block should swap directly on.

 

why not put the LS2 oil pressure sending unit in the 4.8?

also im not following you on the KS..
How are you goin to have an extra? 2 knock sensors on each engine?
just use the LS2 connectors and solder the wires.
Driver side for the front and passenger side for the rear?

 

I see what you're saying now. Split the knock sensor wires in the valley cover on the 4.8 and solder to the ls2 harness knock sensor provisions. That should work. Don't know why I didn't think of it.

I'll double check on the OPSU and see if I can switch it.

Another question, I have the front coolant line from my ls2. On the 4.8 the coolant hard lines run from the front to the back and across, under the intake manifold. On the LS2, am I forgetting something? I don't recall a hard coolant line on the rear of the LS2? If this is the case can I just use stainless braided line with A/N fittings instead, run them over the manifold for the coolant lines?

I definitely appreciate your help. Bare with me and my ignorance of this. I'll get it eventually.

 

I'm second guessing myself? Should I have used the LR4 flexplate instead of the LS2?

I'm reading mixed reviews....