My 3.9 went through this exercise a couple of years back - there is a thread on here about it. Mine was rebuilt with a torque cam and higher compression pistons. The engine which came out was in a pretty bad state - we didn't realise how bad until we had already had the heads reconditioned, so were already too far into the rebuild to through it out and start again.
 
First step is probably to strip it and get everything checked for hardness etc, mine was reheat treated twice to get it to the correct hardness
 
Prices for alternate engines have come down greatly in price and may be a cheaper option than rebuilding the 3.9
 
			
		
Bookmarks