Rebuilding Your Mustang 5.0 Engine

When I found out that my engine had really bad compression, I knew it was time to pull it and freshen it up. I went a lot further than was necessary, but the cost was not that much more, and I have a much nicer finished product as a result. In many cases you can get away with honing the cylinders, and installing new pistons and rings. I kept the stock crank and rods, but had a bit more preparation work done to the assembly.

First you have to find a machine shop you can trust. It is best to ask other racers in your area who they have used in the past, and if they were happy with the results. I used Hedrick's Precision Automotive in Urbana, IL. So far, I have been extremely pleased with the results.

I could have had the block honed and put in new pistons and rings...the bearings were all still in great shape after 80,000 miles. I think I could have stopped here for a price tag of about $550 for the engine work (not including the removal and reinstallation). This would have fixed all of my compression problems, and the bottom end would have been better than stock. My '93 LX was the victim of Ford's changing from forged to hypereutectic ones in the '93 model year. I highly recommend the stronger forged pistons Ford used previously to 1993. They are stronger, but a bit pricier...most of the "experts" agree that forged is the only way to go if you are going to use a power adder. If you plan on using a power adder such as a super/turbocharger or nitrous, you should probably stay with the stock 9:1 pistons. If you plan on running the car without a power adder, you should consider a 10:1 or 10.5:1 compression piston...I don't think you want to go higher unless you want to give up pump gas.

For about another $500 I also had the block bored .030 over, rods resized, the crank polished, and the assembly balanced. You may hear people talking about "blueprinting" their engine. Basically all they are saying is that they have a list of all of the tolerances and what was done to the assembly. Balancing the assembly will result in less vibration, especially at higher RPM's. It also make the rotating assembly more efficient so you make a little bit more power. The net effect is a smoother, longer lasting assembly.

Most machine shops can build the block for you. I elected to save a few dollars and have my step-son do most of the work himself. I had the machine shop install all of the bearings, and press the rods on the pistons (I understand it is easy to break a piston if you don't know what you are doing here). Everything else was done by Willis.

Most people agree that the stock block is pretty sturdy and can handle power to the 600hp range. Unless you feel the need to stroke the engine, or go well over 600hp, the work described above should do very nicely for you. I like dealing with the machine shop rather than over the phone with a company and buying a "crate" engine. I have heard too many stories of poor performing and poorly assembled "crate" engines, that I would stay away from them unless you know for sure that the company you are dealing with has an excellent reputation.

Craig Kiddoo