Tom Wilson
January 1, 2001

Step By Step

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Not even remotely a street piece, the all-new Blue Thunder small-block head is designed for engines that are serious about moving air. Anything less than 350 ci needs a less aggressive head, while at the other end of the scale, 425ci or even larger small-blocks are no problem for the new Blue Thunders. The bigger and nastier the engine, the more benefit these heads will be. They are best suited for engines above 450 horses, but will support all the way up to 1,700. So, they are really ideal for today’s full-boogie Pro 5.0 and Outlaw engines.
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Buyers can choose from two exhaust ports, one at standard 4V-Cleveland height and a 0.750-inch taller version, which is Yates height, much more popular and shown here in our photo subject head. Both use a staggered bolt pattern and easily port to their potential. Expect 200 to 220 cfm from the low port and 270 cfm from the high Yates port out of the box. Fully massaged, the all-out Yates port has returned more than 295 cfm to date. All ports boast a generous 0.400-inch wall thickness for porting freedom.
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Got airflow? Given a quick cleanup with a sanding roll, the Blue Thunder intake ports flow up to 360 cfm at 28 inches of water using a 2.20-inch valve. More extensive pro porting can get these passages higher than 400 cfm says Coast, and the evidence to date suggests even 395 cfm is within reach of moderate porting jobs way up there at 0.800-inch lift. Both Ford Racing Performance Parts and Edelbrock make manifolds to fit this head and keep up with the voracious air demand.
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As with the exhaust ports, the Blue Thunder head is offered with two different-sized combustion chambers: 50 and 70 cc. On a 408-inch Windsor with flat-top pistons, the larger chamber yields 11.8:1 compression or a hair higher, while on the same short-block, the small chamber heads are good for 13:1. Coast can help CNC-up a set of pistons for anyone wanting to fiddle with the compression, including the 15:1 crowd. As for those uncut valve seats, that’s how they come from Blue Thunder so customers can fit whatever valves they want.
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Blue Thunder products are always well-made, feature-filled, and detailed to the nines. Steel washers are required on aluminum heads, for example, so Blue Thunder builds them right into the head. And that small pipe plug on the left—that’s an injection port half drilled and tapped. It makes setting the head up for alcohol something that can be done using a carefully handled hand drill.
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Because the new Blue Thunder race casting will barely run at street-rpm levels, it doesn’t waste any time pretending it is a street head. As the photo shows, there is no exhaust-heat crossover, and there is no air-injection passage (Thermactor) either.
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This logo isn’t well known in Mustang racing circles yet, but let’s see if that doesn’t change soon.
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We asked Coast High Performance to show us the hardware typically packaged with the always-bare Blue Thunder heads. The query resulted in this representative pile of titanium and coiled spring steel. Both the retainers and valves are ti; the springs are duals with dampers. The intake valves should measure at least 2.125 inches, says Coast, and the bore size should be around 4.125 to 4.155 inches to avoid valve shrouding.
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Corner-cutting just isn’t done at Blue Thunder, so the valve guides are premium bronze, and every threaded hole except the sparkplug’s is fitted with steel inserts. The rocker pad area is generous as well, so the valvetrain and stud girdles have good, strong foundations off which to work. Finally, Blue Thunder also offers a porter’s special version of this head. It is the same casting with tons of material left in the ports, and the spring seats are not cut as deeply to allow more radical raising of the port roofs.
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For such hard-running hardware, Blue Thunder parts are something of a well-kept secret. Art Francis, who simply is Blue Thunder, seems to like it that way, knowing that growing a business into the major leagues is probably more hassle than it's worth. But that hasn't stopped him from turning out some spectacular Ford parts. Should you ask around, you'll find Blue Thunder 460 cylinder heads are known to put the hurt on just about anything they cross, and now small-block Fords are about to learn just how hot a Blue Thunder zap really is.

Because Blue Thunder works only through its dealers, we went to Coast High Performance to snap our first look at these awesome castings. Coast retails these heads for $1,799.99 a pair, bare, but can fix you up with anything you need in the way of valvetrain, small parts, intake manifolds, and headers, as well as pistons with domes to match the somewhat unique Blue Thunder chambers if tall compression is desired. At that price it's easy to get excited about a cylinder head Coast's George Klass describes as "the most killer head of all time."

Horse Sense:
A man of principles, Art Francis does things right, all the way down to the packaging. Anyone who's brought forth a set of Blue Thunder cylinder heads from their cardboard shipping cocoons will tell you about the 20 minutes it took and the number of tools they used. Art Francis just smiles and tells you about how many heads he's had damaged in shipping: zero.