Ford Mustang Short-Block Engine Rebuild - Recession Special Part 3

Over the course of the last two months, we've been rebuilding a mild-mannered 302ci short-block for our daily commuter. It generally gets a full tank of 87-octane fout every third day due to our 80-plus-mile commute. That, and a desire for perfect driveability, were paramount in its redesign. Obviously, with these compromises, ultimate power can't be had, but we expect the fun factor to go up considerably, not to mention we won't have to listen to the engine knocking anymore.

In the Oct. '08 issue of MM&FF, we ended our "Recession Special" buildup missing some important parts of the engine that were keeping us from completely assembling the long-block. If you're performing this build with your one and only engine, it probably won't be a problem. However, we were using another core while we continued to drive our daily beater. Eventually we had to tear it down to retrieve things like the camshaft dowel pin, roller lifter dog bones, timing cover, and cylinder-head dowels. We had sourced a bunch of items from a Mustang shop or two, but they didn't have everything, so it was time to get dirty.

Your author spent two eight-hour days pulling the engine and transmission assembly by himself. Since he wasn't working on a flat rate, taking the occasional break to hydrate himself and clean the immense amount of grease from his hands occurred often. If your Mustang resembles the Exxon Valdez under the hood like ours did, you might want to head to the parts store and pick up a box of latex gloves. It's cheaper than buying bags of red rags and is much easier on the hands.

Since we were on the verge of installing the new engine, we moved the long-block from our buddy Dave Young's shop to our home garage. Dave, along with Jason Combs, offered key information on this buildup, but now it was time to do the hard work. After pilfering one of our company engine hoists-we actually disassembled it and brought it home in the subject notchback Mustang-we pulled the oily 5.0 powerplant along with the transmission and disassembled everything. We removed the needed parts from the tired engine and completed our new bullet.

We planned to install the new engine the same way we removed the old one; that is, the engine and transmission as one unit. Before we did that, we cleaned the engine bay with some degreaser, pulled the wiring, scuffed the engine bay with an abrasive pad, wiped it down with brake-parts cleaner, and sprayed it with dark-blue enamel from the parts store. The transmission needed a full detail as well, as just about every gasket on the old engine was leaking. The rear main and rear intake manifold gaskets leaked so much that the inside of the bellhousing was completely slimed. Clutches like the ones used in 5.0 Mustangs don't really like lubrication, and it may have been the reason ours would occasionally slip. Given that we had some future power mods in store for the coupe, we opted to upgrade the clutch using Fidanza's new 2.1 clutch kit. Our stock flywheel was in really bad shape, so we replaced it with Fidanza's nodular iron flywheel.

After installing the engine and turning the key for the first time, we realized there was a humongous exhaust leak at the header collector where it met up with the midpipe. After investigating the issue, we found that the cone flange on the midpipe was coming in contact with the header bolt flanges on both headers. To solve this, we broke out our angle grinder and knocked off about a quarter inch of metal from the midpipe, and that seemed to do the trick. After that modification, the car started and ran pretty good. We then needed to set the fuel pressure, timing and TPS voltage. Base initial timing was set at 12 degrees, but we had to wait until we got the car to the dyno at HP Performance in Orange Park, Florida, before we could set the TPS and fuel pressure, as we didn't have the tools.

With fuel pressure set at 38 psi and TPS voltage set at 0.96 volt, we made our first dyno pull. Peak horsepower came in at 244 and torque twisted up to 290 lb-ft. We noticed there was a slight misfire; a replacement coil cleared up the issue and provided 247 hp and 293 lb-ft of torque at the wheels. Keep in mind, we were running the car on its 87-octane diet. For the next pull, we switched to premium 93-octane fuel and added two more degrees of timing for 14 total at base. Power rose to 249 hp and torque stayed the same at 293.

About this time, we realized that the coolant system was being pressurized, and surmised that we had a damaged head gasket. While the air/fuel ratio looked great on the dyno, and no detonation was detected, we did have some problems with what we thought was air in the cooling system. The usual procedure when refilling a cooling system is to fill it and let it come up to operating temperature so the thermostat opens. Then you can fill the remainder of the system.

Modular cars are far more susceptible to air bubbles in the system, and we thought we had ours taken care of, but the first long drive had us mildly concerned about the temp reading. A subsequent refill and about 20 minutes of idling said everything was OK, but the load that the road and dyno puts on the engine is what made the gasket vent to the cooling system. After contemplating the issue, we came to the conclusion that your author had not properly torqued down the ARP head studs. He had followed the factory torque specs at 72 ft-lb on all bolts. ARP expects you to torque the short studs to 75 ft-lb and the long studs to 85 ft-lb. The long studs run along the top, and that's exactly where the gasket failed.

In the end, we spent over $3,700 on this rebuild, but we did use some items and replaced a few others that you might not need. Without those pieces, the build price tumbles to a hair over $2,400-very doable in this day and age. Horsepower and torque are respectable and should make this Pony gallop a little faster. Whether or not the 2 hp is worth 20 cents extra per gallon is up to you. Given the long commute our project car has each day, the horsepower isn't worth the extra money. That may change, however, as we're looking to install a budget-conscious, intercooled turbo system.