We just pulled my LS 6 engine this weekend and put in a stock LS 2 short block with LS 3 heads and LS 3 intake. We used a lift in a enclosed shop. First, my American Racing headers bolted right on to the LS 3 heads, no problems at all.
We had all the conversion harnesses, just some small items. The map on the rear of my FAST intake which was on the LS 6 engine now went on the front of the LS 3 intake. We just cut and spliced the 3 wires to get the required lenght for the new map location on the LS 3 intake manifold. Also, the small vacum line on the side of the fast intake had to be lenghten for the rear location hookup on the LS 3 manifold. The crank pully on the LS 6 was pulled and put on the LS 2 block as they are different size.
The engine in the cradle was dropped out the bottom, we left the rear end in along with the torque tube. We also just slightly tightened the pressure plate bolts on the clutch, as this allowed us to slip and align the splines extremely easy. Then we just tightened the bolts with the bell housing inspection plate removed, no problems their.
Also put in a LS 7 clutch assembly and a slave cylinder. It was a long 2 days work as we weren't rushing.
The LS 2 short block has a 227/235 cam LSL lobes on a 114 lsa, LS 3 heads are milled to raise the compression, LS 3 intake ported and the LS 2 TB has been ported. LS 3 style 42 lb injectors. These require a wire harness adapter as the injector plug connections are different. It was my friends engine as he went to a new 416 LS 3 in his car.
The engine combination was already dynoed thru a auto. RWHP was 469and rwtq was 430. So we should see maybe some more. Engine fired right up as we had sent the computer out to be flashed with the LS 2 tune he had.
My LS 6 block and heads sold first day, so this exchange was really reasonable. My LS6 clutch was geting old and needed replacement anyway. so overall it turned out good. The new LS 7 clutch is really nice. Would I do this again? Only with friends who know what they are doing and have done it before.
Going to the dyno in a few days, but already can tell it has more hp and tq than my old combination. The new mid range torque is what really is amazing.

 

Keep us posted! I have a similar LS2/3 hybrid stroker build planned for next year. I will likely sell my LS6 as a complete longblock with the AFR heads and FAST intake. I should be able to recover a good amount of money from the swap.

 

im going to do the same, pretty much the same engine i have in my car that im going to try and sell-- im curious as to how much i get out of it.....afr205 heads, fast 92, etc...

 

While sitting in the car wash, engine idling, the exhaust spring on #5 cylinder broke. They are PAC 1518's(single spring). It appears it might be ok, will be doing a leak down test shortly.
If it passes the leak down test, will be going back to double springs. Just found out these springs on this engine were in a batch that were suppose to be recalled.
Is it true you can change springs without removing the heads? If you have, let me know and how hard it was.
TIA.

 

Well, the cylinder held pressure, so we change the valve spring. Fired the motor and runs again like it should. Got lucky as to where the spring broke, but it did fracture.
Learned that the new valve spring tool to change 2 valve springs at a time wouldn't work on the LS 3 heads, as they sent out the wrong tool. Luck had it a old single spring valve compressor worked, so we used it. So, will call tomorrow and get the right one along with new springs and retainers.
Won't be going to the dyno this week, it may be next several weeks off. But when I get the new dyno results, will post them.