I found a 5.3 for 150 bucks from a buddy and was thinking about dropping it in the trans am just to get it back on the road. I've got a ms3 cam just sittin here outta the old blown motor and was thinking about dropping it in the 5.3 just for a lil sound. Would I be better off using my 241 heads or stick with the 706s that's on the 5.3. And will my 7.4 pushrods still gonna be the right length in the 5.3 ? Any help or insight is greatly appreciated.

 

I am interested in this as well.

 

If the objective is just to get the car back on the road then leave the LM7 mostly stock. MS-anything will run like a terd in it

 

Omg...

 

Not looking to make a street racer here guys just get the wheels rolling again and get the rust off the rotors. Just wanted to reuse the cam for the wonderful exhaust note and the computer in the car is programmed for the ms3. On a tight budget for the time being . The 346 got grenaded when the head gasket decided to give way at 7200 rpms and filled # 7 cylinder with water. If the 5.3 w/ the cam is gonna be a straight terd I'm not even gonna mess w/ it. Just tired of seeing ol' betsy sitting in the yard collecting dust

 

That cam is way too big for the 5.3. Find a used 224 or 228 and use that instead. Keep the rpms to 6500 max.
Save some $$ and you can punch out the 5.3 to 5.7 or even 38x (with 4.0 crank) in the future. Then you can reuse the MS cam.

 

If you still have a stock LS1 cam then slide it in the 5.3, otherwise just rock it stock until you build a better engine

Whatever tune you had on the old 346 wont apply to the 5.3 without tweaking

 

Found a ls6 block I'm going with instead $200 for it and try n use what internals I have that are salvagable. Hoping just replace that 1 rod and piston a new set of bearings and rings a quick hone and she'll be ready once again. Any other ideas or precautions u can think of. Other than having crank polished?

 

So, you're saying it is worth removing the stock LM7 cam (45x/46x lift, can't remember the exact number) and installing an LS1 cam (500/500 lift)? I do have one laying around and the 5.3 is out of the car right now with no balancer on it. Yes, it would be the time to swap but, don't want to do it for 5 hp. 5.3 going into car for now, LS1 is up and coming build. Has anyone actually done this swap?

 

Lift isnt as important to LSx engines as duration. Id suggest the LS1 cam because its pretty much a freebie mod over the lame truck cam on 191/191. That way the TA wont feel like a farm truck until the new engine goes in

 

I guess this swap for me is as easy as it will get and won't cost anything, done deal. I'm assuming the added duration will give it more mid-range and top end over the LM7 cam, right? ~ .050 more lift has to help some I'd think as well. Stock head flow is probably giving up at that point too. Could you explain the theory on duration being more important than lift on LS motors? I'm starting to see more of my SBC notes going to the achives! LOL