Mustang MonthlyHow To Engine
How to: Build a 429 Super Cobra Jet
We get 467 horsepower from an iron-head 385-series-big-block
Cobra Jet Block
The 429 Cobra Jet block (Ford part number D0OE-B) was a limited-production block casting with four-bolt mains, thicker main webs and cylinder walls, and a "CJ" cast in the lifter valley. Expect to see a D0VE-A or D1VE-AA casting number. There is also a 460 truck block with a D7TE or D8TE casting number also machined for four-bolt mains. It has 4.360-inch bore just like the 429 CJ/SCJ block. Unless you are concerned with a matching number block, the 460 truck casting is a drop-in replacement. Another consideration is being able to convert any 429/460 block to four-bolt mains because there's plenty of web thickness to get the job done if you have four-bolt main caps.
No Worries Over Zinc
Recently, there has been concern about the removal of zinc and other additives from engine oil because they are believed to harm the catalytic converters in newer vehicles. By eliminating these additives, a new challenge has been created for classic car owners—excessive flat tappet cam lobe wear and failure. Comp Cams has chosen to do something about this problem in its #1590-12 Engine Break-In Oil with ZDDP enhancement, which provides protection for moving parts during the critical first firing and break-in period. Because JGM is running a traditional flat-tappet camshaft, protection is important so Grubbs poured seven quarts of 10W30 weight Comp Cams Engine Break-In Oil in the pan to help get this SCJ off to a good start. Comp Engine Break-In Oil is available in 10W30 and 15W50.
Cobra Jet Induction
Ford's 429 was fitted with two basic four-barrel intake manifolds—D0OE-9425-D designed for a spread-bore carburetor (four-barrel and Cobra Jet) and D0OE-9425-C for the Holley 4150/4160 square flange (Super Cobra Jet). Both are cast-iron and weigh as much as a bank vault. There is also a variety of great aftermarket manifolds, both vintage and contemporary, that perform very well. If you are going for raw high rpm horsepower, you want a deep breathing single-plane manifold. For the street, a dual-plane manifold yields a broad torque curve that begins to come on strong at 2,000 rpm and pulls like stink through 5,500.
You won't see a Ford part or engineering number on a Ford Quadrajet. According to the Ford Carburetor Guide by Pony Carburetors and the late Jon Enyeart, there are four numbers that apply only to Ford Quadrajets—7040285, 7040286, 7040287, or 7040288. If it doesn't have one of these numbers, it is not a Ford Quadrajet. The 429 is the only Ford engine ever fitted with a Quadrajet.
SCJ Truth Telling
How is it possible that an engine factory rated at 375hp, 450 lb-ft of torque can make so much power (nearly 100 horsepower and 30 lb-ft more!) on JGM's Superflow 901? Much of it boils down to blueprinting, dynamic balancing, head porting, a Holley 750-cfm HP carburetor, PerTronix distributor with Ignitor II, and precision tuning. On the dyno, the JGM 429 SCJ exhibited a broad torque curve and real horsepower on the high end considering this is an iron stocker with a stock spec cam.
There are two points to consider here. One, factory horsepower and torque numbers aren't always true, typically founded under controlled conditions. Detroit automakers had to lower published horsepower and torque numbers due to insurance rates, especially for younger drivers. In truth, the 429 SCJ produced more like 425-450 horsepower and 480 lb-ft of torque, more on a par with the big-block Chevy. These numbers demonstrate what you can do with a 429 SCJ stocker. Imagine what this thing would do with aftermarket heads and induction along with a hot mechanical roller cam.