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Ford Mustang Short-Block Engine Rebuild - Recession Special Part 2
Ported Factory Heads And A Crane Cam Add Sizzle To Our Commuter Special.
Last month, we brought you the beginning of a budget-minded engine buildup ("Recession Special," Sept. '08), which, when completed, will be shoehorned between the fenders of a well-used '90 5.0L Mustang. This month, we bring you Part 2 of that buildup, which will include a trick set of ported factory cylinder heads, a mild camshaft from Crane Cams, and the installation of the rotating assembly in our freshly stone-honed 302ci block.
When we left off, we had performed the stone hone on the eight holes of our 5.0 block, polished the stock crank's journals, and installed the piston rings on our factory forged slugs. For this installment, we started by installing the crank main bearings, followed by the crank itself. We then installed the piston/connecting rod assemblies into the block.
One thing we forgot to do during the cleaning process was to chase the various threaded holes in the engine block, such as the cylinder head and oil-pan bolt holes. Degreaser and compressed air can get a lot of the junk out, but a threaded tap will clean up the threads and remove any old gasket or fastener sealer. Then you can perform a final cleaning of the block before installing the rotating assembly.
You'll want to check out the captions for the details on how we checked the various bearing oil clearances, after which we installed the rotating assembly. Plan on popping for a piston-installation tool, which squeezes the rings into the piston so that the assembly will slide down easily into the cylinder. Take care when tapping them in, so you don't hang a ring up on the deck surface and break it. We did just that, but we had kept a few of the stock rings just in case something like this happened. If this were a more serious piece of hardware, we would've hit up Mahle Clevite for another ring set, but we won't be setting any records with this powerplant, as it's destined for commuter duty.
Once the rotating assembly was installed and torqued to factory specifications, we were ready for the cylinder heads. The 5.0 aftermarket is flooded with choices that will improve on the factory E7TE cylinder heads, but after visiting the Thumper Performance Web site, we opted to use a set of its ported factory castings to curb the overall cost while improving performance. In addition to the porting and polishing that was performed, Thumper proprietor Mike Schultz recommended we upgrade the E7's 1.78-inch intake and 1.46-inch exhaust valves to the larger 1.84-inch intake and 1.54-inch exhaust GT-40 valves.
The porting process makes a number of changes to the intake and exhaust runners, and both openings are matched to Fel-Pro 1250 intake gaskets and 1415 exhaust gaskets. We also had Thumper match our lower intake manifold to the 1250 gasket as well, and we'll cover that next month.
While Thumper specializes in E7TE castings, it also offers ported GT-40P and GT-40 castings. We went with what we had, which were the original stock heads from the engine. After performing well for some 140,000 miles, they deserved a makeover of sorts. Thumper offers a number of head configurations that include stock valve sizes, GT-40 valves, stainless valve upgrades, and a few different spring packages. Prices start at $595 for a complete package with stock-type valves and a 0.500-inch lift valvespring set, and there's a refundable $100 core fee. Schultz pointed out that the real bargain these days are the GT-40P Explorer castings that are readily available in most salvage yards and can be had fairly cheap. Thumper Performance also offers head/cam packages that include the ported castings along with a Ford Racing Performance Parts B303, E303, or TFS Stage 1 hydraulic-roller camshaft.
"Usual results on a head and cam package drop elapsed times anywhere from 0.6 to 0.8 second," Schultz says. "With heads, cam, and intake mods, we've seen over 1.4 seconds off e.t.'s."