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Aluminum Head 427 - FE = Real Iron, Part 1We build Not one, but two aluminum-head 427 FE side oiler Cobra big-blocks. From the September, 2012 issue of Modified Mustangs & Fords By Jim Smart Photography by Jim Smart
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If I remember high school science class accurately, the "Fe" symbol on the periodic table of elements means iron, correct? However, when we observe this pair of 427 "FE" iron, side oiler big-blocks JGM Performance Engineering just amassed, built, and dyno tested, you could have fooled us. Sure looks like a lot of lightweight non-ferrous metal on top--C5AE-6090-H Cobra Medium Riser cylinder heads with aluminum and magnesium induction you don't see everyday. And like most things Ford, it isn't always easy to explain. How did these two 427 side oiler blocks arrive at this location, at this moment in time, and what do we do with them? When Jim Grubbs of JGM invited us into his Valencia, California, shop for a closer look at these engines, there was more there than anyone bargained for, as both blocks had unique and noteworthy histories. Both engines were for the same customer, a Cobra-builder with a deep passion for Shelby power. One engine would be a dyno-tested, stock "Cobra" build to be put on static display in the client's office. The other would be stroked to 482 ci, installed in a Daytona Coupe, and raced. Follow along as we take you through the builds of each of these remarkable powerplants. This month, we start with the stock 427 buildup. Block 1 will be assembled as a 427 Cobra mill just as they came from Shelby American in the mid-1960s, yet Block 1 will never be considered mundane because it's a C6AE-B SOHC block. Yes, genuine SOHC iron discovered during mock-up and final assembly. We spotted the block's unique demeanor when our eyes rolled across the decks and noticed additional 5/8-inch oil drain passages--not seen on 427 FE wedge blocks. It will be built, dyno tested, and placed on static display. Block 2 is a real 427 Cobra side oiler wedge block with its original Shelby Cobra VIN stamped in the iron. Several attempts to notify the Shelby American Automobile Club (SAAC) of this find went without a response, yet the matching vehicle survives according to the Shelby World Registry. Block 2 is being built as a 482ci stroker with more than 600 horsepower on tap. Cross-Bolted/Side Oiler Need To KnowCross-bolted FE blocks first entered production in the 406 late in 1962 and into 427 production for 1963. Not all 427s have cross-bolted main caps. There are center oilers and side oilers. Some folks call center oilers "top oilers." And because the casting process wasn't always straightforward, you can expect to see some odd-duck combinations out there. You may see a side oiler block that isn't drilled for side oiler galleys. You may even see a 360 or 390 block that's part side oiler casting. You can't always count on a casting number to accurately identify a block. And one more thing--to the best of our knowledge, the SOHC block with its 5/8-inch oil drainback doesn't have a Cammer specific casting number. Some blocks were drilled for the SOHC head with the 0.040-inch taller deck yet they had the same casting number as a side oiler wedge block without the drain passage. We may get arguments on this one. However, this is based on what we've seen and from what seasoned FE builders have told us. Always interested in reader feedback on this subject if you can come up with a consistent pattern. Our friend at Total Performance in Mount Clemens, Michigan, John Vemeersch, is a longtime Ford racer and engine builder from way back and is an excellent source for information and Ford engine parts. He's a good contact for anyone baffled by a Ford casting they cannot explain.  There are six side bolts,...  There are six side bolts, washers, and spacers in a 427 cross-bolt block.  Thick, flat washers go under...  Thick, flat washers go under the bolt head for security and bolt tension. Use Permatex's The Right Stuff between the bolt head, washer, and block to prevent oil leaks. Cross bolts are torqued first to 20 ft-lbs, then, 40 for final torque. Bolts must be torqued in a specific crisscross pattern beginning at the front two, then the back two, then the center. Main cap bolts have to be torqued first to 95-105 ft-lbs. Fasteners can be sourced from ARP or AMK Products.  Spacers should be installed...  Spacers should be installed before main caps are torqued. Once the spacers and cross bolts are installed, but not torqued, torque main caps to 95-105 ft-lbs in one-third values—35, 70, and 105 ft-lbs. This allows the cap to settle and seat with gradually increasing bolt tension.  1a At first glance, Block...  1a At first glance, Block 1 looks like any other 427 side oiler with cross-bolted main caps. This one is a C6AE-B 427 SOHC block with 5/8-inch deck-to-valley oil drain-back holes at the rear for SOHC heads.  1b You can mount wedge heads...  1b You can mount wedge heads on an SOHC block, but you can't mount SOHC heads on a wedge block. The SOHC block has a 0.040-inch taller deck height, which is yet another difference between it and the wedge block.  2 This is the 5/8-inch diameter...  2 This is the 5/8-inch diameter oil drain-back hole located at the rear of each deck for the SOHC's extraordinary hemispherical chamber cylinder heads. For wedge heads, these passages get 5/8-inch pipe plugs and are not used.  3a Although seasoned Cobra...  3a Although seasoned Cobra guys don't give these rare C5AE-H Medium Riser aluminum head castings much thought, they're quite a sight for the novice who never sees them.  3b JGM Performance Engineering...  3b JGM Performance Engineering has checked these castings thoroughly and found their dimensions to be the same as Medium Riser iron castings. They save weight and extract engine heat, however, airflow, port, and valve size are the same. Flow bench figures are the same as their iron counterparts.  4 C5AE-H 88-91cc shovel chambers...  4 C5AE-H 88-91cc shovel chambers and valve sizes are the same as iron Medium Risers. In short, no real power gain from these rare castings. Less weight and you can run a pinch more compression thanks to better heat transfer.  5 Oil galley/bearing indexing...  5 Oil galley/bearing indexing is perfect, which isn't always true with FE castings. We've seen a number of FE big-blocks where oil passage and bearing indexing isn't up to par. If you see two-thirds or less oil passage at the bearing hole, it isn't enough. You'll need to hog out the oil passages for improved oil flow.  6 This is a Ford experimental...  6 This is a Ford experimental steel crank with an XE part number and C-clip galley plugs. It has been dynamically balanced and checked for weaknesses. It's good to go.  7a A closer look at this...  7a A closer look at this steel XE crank shows "XE 132391." Some, but not all, main journals have this oil distribution slot for improved flow. Word on the street is that a bunch of these cranks were produced and tested by different factions.  7b If you find one, there's...  7b If you find one, there's no telling what you'll see, because these were individually produced pieces for testing purposes. Some have every journal slotted, while with others it's random. What we do know is it can weaken the journal, so be careful. Some steel cranks have this C-clip-secured oil galley plug. Others are screw-in pipe plug.  8 Jim Grubbs installs and...  8 Jim Grubbs installs and secures all main bearing caps first, but doesn't torque them. They are hand-tightened first to seat caps. Side bolts and spacers must be mocked up and fitted before main caps get full torque. Remember, iron shifts during machining, which means spacers that fit during disassembly may not fit now.  9 When there's too much clearance...  9 When there's too much clearance between main caps and block skirts, one technique is to dimple the boss to help take up clearance. JGM had to make custom spacers because this block arrived without them.  10 Crankshaft endplay is...  10 Crankshaft endplay is checked with the main caps snug, but not tight. Endplay should be 0.004- to 0.010-inch. Maximum allowable is 0.014-inch.  11a FE #5 main bearing caps...  11a FE #5 main bearing caps and the four seals require close attention. Fit the cap with side seals (2) and ascertain proper seating. Stagger the rear main seal ends (at crank) and touch the tips with The Right Stuff sealer.  11b The rear main seal lip...  11b The rear main seal lip must be pointed inward and be generously lubricated at the lip only, never the outside perimeter. Side seal tips get The Right Stuff too. The outsides get a mild coating of 30-weight engine oil. Slowly drive these pins in with lubrication and patience.  12 Because this is a box...  12 Because this is a box stock 427 with minor upgrades--like forged pistons--it gets a factory grind, flat-tappet mechanical cam and solid lifters. Professional and amateur builders mess this up all the time. Engine assembly lube on journals and moly coat on lobes. Never use moly coat on journals. And by the same token, never use lube on lobes. This is crucial to proper cam lobe hardening during initial fire-up.  13 JGM has opted for Speed-Pro...  13 JGM has opted for Speed-Pro forged pistons and an 0.030-inch overbore from an original standard bore block. JGM has done mock-up and found, based on calculations, they will get approximately 11.5:1 compression. These domed pistons deliver an 11.5:1 compression ratio when combined with 88-91cc Medium Riser chambers. Although we see rings rolled on in a lot of shops, JGM uses a ring expander for uniform expansion without ring distortion.  14 This C6AE-E 427/428 SCJ...  14 This C6AE-E 427/428 SCJ rod with cap screw bolts is plenty of rod for what we're doing here. This isn't the brute Le Mans rod, but more than adequate for an engine we're going to take to 6,500 rpm. Rods have been reconditioned and fitted with ARP bolts.  15 JGM uses billet ring compressors...  15 JGM uses billet ring compressors for best results, but not everyone can afford them. Main thing is to generously lubricate cylinder walls and pistons with 30-weight engine oil or assembly lube if it's going to sit a while. Ring end gaps should always be 45 degrees out from one another, though they're going to move.  16 ARP rod bolts are torqued...  16 ARP rod bolts are torqued to 53-58 ft-lbs, best done in one-half values—25, then a full 55-58 ft-lbs. Check side clearances and freedom of rotation before moving on to the next rod.  17a JGM Performance Engineering...  17a JGM Performance Engineering stresses strict documentation on everything it does. All measurements and procedures are documented for the record and future use. A permanent record is kept on every engine build along with a reference number. When you build your 427 FE, keep a permanent record of everything you do along with part numbers and dimensions. 17b If a shop does the work for you, insist it does the same. Next month, we're going to wrap up our 427 Cobra FE big-block and spin it on JGM's 901 dynamometer, along with its soul mate, the 482ci big-bore stroker. We will have complete parts and dyno information for you then.
 | JGM Performance Engineering puts two decidedly different 427 FE big-blocks on the dyno. |
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