How-To Build A Ford Mustang Engine Right
Avoiding The Faux Pas That Can Cost You Plenty
Seal The DealCoolant escapes from water jackets more times than not, because we fail to use bolt thread sealer during assembly. This is especially important when we have a "wet" deck where the head bolt threads into the water jacket. Use ARP thread sealer whenever you're in doubt; then sleep comfortably.
Use The Right HeadYou'd think we'd have this down by now, but we don't. If you're building a hot FE big-block for your '67-'70 Mustang, don't forget to use the appropriate cylinder heads. FE heads designed for the Mustang, Cougar, Fairlane, and Comet have four exhaust-manifold bolt holes (shown). If your custom-built 390 High Performance has '61 C1AE Hi-Po heads, you're going to kick yourself when it's time to install the headers, because those very necessary bolt holes won't be there.
Overcarburetion!You'd be amazed at how many rides we see out there with huge carburetors overfeeding modest engines in need of less. According to Jon Enyeart of Pony Carburetors, "If you have a stock 289 or 302 4V engine, you don't need more than 500 cfm; if it's a 351W, no more than 550-600 cfm. Big-blockers in the 390-428ci range need only 600-650 cfm to get the job done. We know Ford put 735-cfm carburetors on 428 Cobra Jets, but these engines didn't need that much carburetor. A 428 Cobra Jet can get by with 650 cfm, believe it or not. In fact, you'll achieve better low-end torque with a smaller Holley; no foolin'."
Have You Heard This One?You may think this is impossible, but it's possible to get small-block Ford connecting rods mixed up. At first glance, 221, 260, 289, and 302 connecting rods look the same. You'd be surprised how many 302 rods wind up in 289 engines and vice versa. The problem is that we run into piston height issues either way. The 221, 260, 289 rod is easily identified as the C3AE forging, while the 302 rod is the C8AE forging. Remembering this important fact will save you a lot of grief. By the same token, remember that the 221, 260, 289 crankshaft is identified with a "1M," whereas the 302 crank is a "2M" casting. Rods and cranks must be compatible.
Use A Torque PlateNot all machine shops use torque plates when boring and honing blocks, but yours should. "The torque plate is a steel plate bolted to the deck of the block during boring and honing to simulate cylinder head stressing," said Naegele. "We want the cylinder bores machined and honed as though heads were installed for optimum results. If we bore and hone a block without the torque plate, cylinder dimensions will change when we install the heads, which can adversely affect the piston-to-cylinder wall marriage."
Cam Bearing 101Do you know what kills an engine more quickly than anything? Oil starvation. Oil starvation occurs when we install the cam bearings incorrectly and forget to line up the oil holes. Laugh if you will, but we see this time and time again, and it's darned costly. Someone gets in a hurry during assembly and doesn't check oil galley hole alignment in the cam bearings. Oil must be able to pass from the filter to the cam and the main bearings or it gets real ugly real fast. Always double-check cam bearing oil passage alignment before assembly begins.
Checking ClearancesYou'd be surprised at how many engine builders finish a job up, only to discover an unexplainable rapping noise in the pan during fire-up. Today's oil pump castings aren't always kind about clearing the crankshaft counterweights in small-block Fords. Sometimes the counterweight brushes the oil pump. This is a very important clearance you'll want to check. Make sure the pump clears the counterweight by at least 0.040 inch. This will allow for expansion as the engine warms up.
We hope these tips will prevent you from destroying your engine. We also hope they will make your engine perform as Ford intended or, if your aim is modification, better than Ford envisioned.