1. The assembled Super Cobra Jet short-block demonstrates what makes an SCJ a standalone high-performance engine. Both the Cobra Jet and Super Cobra Jet use the same block, crank, and rods. Where they differ is camshaft, valvetrain, and induction. You can take a Cobra Jet and make it a Super Cobra Jet with a hot mechanical roller cam, stud-mounted adjustable rockers, and Holley induction.
2. The Cobra Jet and Super Cobra Jet employ the same four-bolt main D0OE-B “CJ” block. Casting number is D0VE-A.
3. Jim Grubbs is fitting his Super Cobra Jet with Speed Pro forged .030-inch oversize flat-top pistons and D0OE-A forged Cobra Jet rods to achieve 10.54:1 compression. This makes for a good street engine that will run on pump gas and octane boost.
4. Although this is a 460 cast crank with a “2Y” designation, this is where you can expect to find a 429’s “4U” or “4UA” marking. If you see a “4U” or “4UA” marking, you’ve found a 429 crank with 3.590-inch stroke. If you see “2Y” or “3Y,” you’ve found a 460 crank with a 3.850-inch stroke. A 429 Cobra Jet or Super Cobra Jet crank will have a Brinell hardness-tested dimple mark in the first counterweight.
5. Speed Pro forged pistons with low-friction coated skirts are carefully assembled using a piston ring expander. These are iron rings engineered to seat uniformly for good cylinder sealing. Ring end gaps are positioned 90 degrees apart—quarterly—to keep them far apart.
6. The rings are generously lubricated with SAE 30 weight engine oil or engine assembly lube for installation into the block. JGM Performance Engineering uses billet piston ring compressors.
7. The 429’s oiling system is adequate for any performance mission with two galleries running the length of the block in a fashion similar to the 351C but with priority to main and rod journals.
8. The Speed Pro high-volume oil pump and pick-up have been inspected with clearances checked. Pressure should be 10 pounds for every 1,000 rpm.
9. We’re running a Crane #35-D0AZ-D (#96801) flat-tappet mechanical cam with .298-inch lift (.510-inch at the valve with 1.71:1 rocker ratio) and 266 degrees advertised duration. This is a stock cam grind good from 2,200 to 5,200 rpm. JGM has degreed this cam and found it to be within specifications. We’re running Comp Cams #817-16 lifters with .012-inch oil holes in the face to reduce lifter and lobe wear.
10. Because we’re running a dual roller timing set, JGM has eliminated the oil slinger, which would interfere with the chain.
10a. The 429 and 460 get a spacer between sprocket and damper.
11. One mistake we often see is excessive use of sealer. All you need is a thin film of Permatex’s The Right Stuff on clean surfaces and you won’t have leaks. Where end rail rubber gaskets meet side gaskets, apply a dab of The Right Stuff at the joints and carefully install the pan. Do not overtighten fasteners. Snug in a crisscross fashion and slowly tighten to specs found in your Ford Shop Manual.
12. The reason these big-blocks make so much power is cylinder head technology, similar to 351 Cleveland with huge ports, poly-angle (canted) valves, high-quench 72-74cc chambers, and stud-mounted adjustable rockers and guideplates.
12a. The reason these big-blocks make so much power is cylinder head technology, similar to 351 Cleveland with huge ports, poly-angle (canted) valves, high-quench 72-74cc chambers, and stud-mounted adjustable rockers and guideplates.
13. This is a Super Cobra Jet head with stud-mounted adjustable rockers and guide plates. Cobra Jet heads use non-adjustable bolt/fulcrum stamped steel rockers without studs and guide plates.
14. Fel-Pro Print-O-Seal gaskets have been chosen for this project.. Heads are torqued in one-third valves to 130-140 lb-ft to allow good gasket compression and bolt stretch. use a thin film of The Right Stuff where the intake manifold and cylinder head meet.
15. Fel-Pro Print-O-Seal intake gaskets are suggested for positive sealing. It is suggested you apply a thin film of The Right Stuff at port bottoms to prevent engine oil from being ingested from the valley. Also use The Right Stuff at the block rail ends instead of cork gaskets. As the sealer cures, it expands and seals.
16. JGM asked for the PerTronix billet Ford distributor (#D132710) with Ignitor II to work with a Flamethrower coil (#40011) and 8mm black ignition wires (#808220). The PerTronix distributor fits 351C and 429 engines. If you’re using a roller camshaft, swap in a steel, bronze, or composite distributor gear from Comp Cams.
17. Valve lash is adjusted per the firing order at .022-.024-inch cold. You want the valve seated so it has just closed. The valve stem and rocker tip should be coated with engine oil, which also applies to clearances,
The 429 Cobra Jet/Super Cobra Jet block is a unique casting with “CJ” cast into the lifter valley with four-bolt mains down under. JGM Performance Engineering has studded these main caps with ARP studs for rigidity and security.
The 429 Cobra Jet/Super Cobra Jet block is a unique casting with “CJ” cast into the lifter valley with four-bolt mains down under. JGM Performance Engineering has studded these main caps with ARP studs for rigidity and security. ▲You should see a D0VE-A or D1VE-AA casting number in addition to “CJ” in a Cobra Jet block. Just the D0VE-A or D1VE-AA alone does not guarantee a Cobra Jet block. Pull the oil pan and intake manifold to ascertain four-bolt mains and “CJ” casting mark.
The D0OE-9425-C iron manifold for Super Cobra Jet is sized for the Holley 4150/4160 flange and fits everything from 500 to 1,000 cfm.
Ford Racing's M-9424-J429 dual-plane aluminum high-rise is designed for spread-bore carburetion, although you could get away with a Holley 4150-4160. This manifold weighs considerable less than the iron factory manifolds.
Weiand's Stealth dual-plane manifold offers great low to mid-range torque and comes strong at high rpm. You get both worlds because there's good low-rpm velocity through long runners. At high rpm, the high runner ceilings provide increased airflow. it takes traditional high-rise technology a step further.
This is the iron D0AE-9425-D 429 four-ballre and Cobra Jet manifold for spread-bore carburetors like the Rochester QuadraJet and Holley Spread-Bore.
Rochester's QuadraJet was first introduced in 1965 as an approach to a more fuel-efficient four-barrel carburetor thanks to small primaries and large secondaries with air valve. When properly tuned, the QuadraJet is a terrific carburetor with a smooth transition from primaries to all four holes. The 715-cfm QuadraJet was installed on the '70-'71 429 and the 429 Cobra Jet.
JFM's 429 Super Cobra Jet is fitted with a Holley 750-cfm HP Series carburetor, which certainly contriubed for our 429's 467.2 horsepower and 480.7 lb-ft of torque. We're convinced an 800- or 850-cfm HP would have needed closer to 500/500.
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1. The assembled Super Cobra Jet short-block demonstrates what makes an SCJ a standalone high-performance engine. Both the Cobra Jet and Super Cobra Jet use the same block, crank, and rods. Where they differ is camshaft, valvetrain, and induction. You can take a Cobra Jet and make it a Super Cobra Jet with a hot mechanical roller cam, stud-mounted adjustable rockers, and Holley induction.
2. The Cobra Jet and Super Cobra Jet employ the same four-bolt main D0OE-B “CJ” block. Casting number is D0VE-A.
3. Jim Grubbs is fitting his Super Cobra Jet with Speed Pro forged .030-inch oversize flat-top pistons and D0OE-A forged Cobra Jet rods to achieve 10.54:1 compression. This makes for a good street engine that will run on pump gas and octane boost.
4. Although this is a 460 cast crank with a “2Y” designation, this is where you can expect to find a 429’s “4U” or “4UA” marking. If you see a “4U” or “4UA” marking, you’ve found a 429 crank with 3.590-inch stroke. If you see “2Y” or “3Y,” you’ve found a 460 crank with a 3.850-inch stroke. A 429 Cobra Jet or Super Cobra Jet crank will have a Brinell hardness-tested dimple mark in the first counterweight.
5. Speed Pro forged pistons with low-friction coated skirts are carefully assembled using a piston ring expander. These are iron rings engineered to seat uniformly for good cylinder sealing. Ring end gaps are positioned 90 degrees apart—quarterly—to keep them far apart.
6. The rings are generously lubricated with SAE 30 weight engine oil or engine assembly lube for installation into the block. JGM Performance Engineering uses billet piston ring compressors.
7. The 429’s oiling system is adequate for any performance mission with two galleries running the length of the block in a fashion similar to the 351C but with priority to main and rod journals.
8. The Speed Pro high-volume oil pump and pick-up have been inspected with clearances checked. Pressure should be 10 pounds for every 1,000 rpm.
9. We’re running a Crane #35-D0AZ-D (#96801) flat-tappet mechanical cam with .298-inch lift (.510-inch at the valve with 1.71:1 rocker ratio) and 266 degrees advertised duration. This is a stock cam grind good from 2,200 to 5,200 rpm. JGM has degreed this cam and found it to be within specifications. We’re running Comp Cams #817-16 lifters with .012-inch oil holes in the face to reduce lifter and lobe wear.
10. Because we’re running a dual roller timing set, JGM has eliminated the oil slinger, which would interfere with the chain.
10a. The 429 and 460 get a spacer between sprocket and damper.
11. One mistake we often see is excessive use of sealer. All you need is a thin film of Permatex’s The Right Stuff on clean surfaces and you won’t have leaks. Where end rail rubber gaskets meet side gaskets, apply a dab of The Right Stuff at the joints and carefully install the pan. Do not overtighten fasteners. Snug in a crisscross fashion and slowly tighten to specs found in your Ford Shop Manual.
12. The reason these big-blocks make so much power is cylinder head technology, similar to 351 Cleveland with huge ports, poly-angle (canted) valves, high-quench 72-74cc chambers, and stud-mounted adjustable rockers and guideplates.
12a. The reason these big-blocks make so much power is cylinder head technology, similar to 351 Cleveland with huge ports, poly-angle (canted) valves, high-quench 72-74cc chambers, and stud-mounted adjustable rockers and guideplates.
13. This is a Super Cobra Jet head with stud-mounted adjustable rockers and guide plates. Cobra Jet heads use non-adjustable bolt/fulcrum stamped steel rockers without studs and guide plates.
14. Fel-Pro Print-O-Seal gaskets have been chosen for this project.. Heads are torqued in one-third valves to 130-140 lb-ft to allow good gasket compression and bolt stretch. use a thin film of The Right Stuff where the intake manifold and cylinder head meet.
15. Fel-Pro Print-O-Seal intake gaskets are suggested for positive sealing. It is suggested you apply a thin film of The Right Stuff at port bottoms to prevent engine oil from being ingested from the valley. Also use The Right Stuff at the block rail ends instead of cork gaskets. As the sealer cures, it expands and seals.
16. JGM asked for the PerTronix billet Ford distributor (#D132710) with Ignitor II to work with a Flamethrower coil (#40011) and 8mm black ignition wires (#808220). The PerTronix distributor fits 351C and 429 engines. If you’re using a roller camshaft, swap in a steel, bronze, or composite distributor gear from Comp Cams.
17. Valve lash is adjusted per the firing order at .022-.024-inch cold. You want the valve seated so it has just closed. The valve stem and rocker tip should be coated with engine oil, which also applies to clearances,
The 429 Cobra Jet/Super Cobra Jet block is a unique casting with “CJ” cast into the lifter valley with four-bolt mains down under. JGM Performance Engineering has studded these main caps with ARP studs for rigidity and security.
The 429 Cobra Jet/Super Cobra Jet block is a unique casting with “CJ” cast into the lifter valley with four-bolt mains down under. JGM Performance Engineering has studded these main caps with ARP studs for rigidity and security. ▲You should see a D0VE-A or D1VE-AA casting number in addition to “CJ” in a Cobra Jet block. Just the D0VE-A or D1VE-AA alone does not guarantee a Cobra Jet block. Pull the oil pan and intake manifold to ascertain four-bolt mains and “CJ” casting mark.
The D0OE-9425-C iron manifold for Super Cobra Jet is sized for the Holley 4150/4160 flange and fits everything from 500 to 1,000 cfm.
Ford Racing's M-9424-J429 dual-plane aluminum high-rise is designed for spread-bore carburetion, although you could get away with a Holley 4150-4160. This manifold weighs considerable less than the iron factory manifolds.
Weiand's Stealth dual-plane manifold offers great low to mid-range torque and comes strong at high rpm. You get both worlds because there's good low-rpm velocity through long runners. At high rpm, the high runner ceilings provide increased airflow. it takes traditional high-rise technology a step further.
This is the iron D0AE-9425-D 429 four-ballre and Cobra Jet manifold for spread-bore carburetors like the Rochester QuadraJet and Holley Spread-Bore.
Rochester's QuadraJet was first introduced in 1965 as an approach to a more fuel-efficient four-barrel carburetor thanks to small primaries and large secondaries with air valve. When properly tuned, the QuadraJet is a terrific carburetor with a smooth transition from primaries to all four holes. The 715-cfm QuadraJet was installed on the '70-'71 429 and the 429 Cobra Jet.
JFM's 429 Super Cobra Jet is fitted with a Holley 750-cfm HP Series carburetor, which certainly contriubed for our 429's 467.2 horsepower and 480.7 lb-ft of torque. We're convinced an 800- or 850-cfm HP would have needed closer to 500/500.