The Ford 428 engine was the go to big block engine. You want more horsepower, get more displacement. Then in Mid 1968 Ford started offering the 428 block with some 427 parts. The 427 engine did not have the long term reliability needed for street cars.
The Cobra Jet 428 had 427 lower rise heads, a cast iron copy of the aluminum 390 Police Interceptor intake manifold, the 390 GT’s hot hydraulic cam, a huge 735 cfm Holley 4 barrel and a better exhaust manifold. Ford rated it at 335 HP at 5,600 rpm with 445 lb-ft of troque at 3,400 rpm. That’s 10 more horsepower than the 390 GT engine. The NHRA quickly realized that HP rating was not even close and bumped 428 CJ cars into a higher class. Hot Rod magazine dyno’d the engine at got 365 HP at 4,800 rpm. After breaking the motor in more, the HP came up to 375. The W-code 427 and the 428 CJ shared about everything inside except the main bearing caps and the bore/stroke.
So who came up with the idea of using 427 & 390 parts in a workhorse 428 block. It wasn’t a Ford engineer. In fact, it came from Tasca Ford. They were into racing in a big way during the mid 60’s. Chevy and Chrysler were putting out some pretty awesome cars with more performance than the Fords. The small block and even the 390 Mustangs were no match for the Chevy 327 engine in a Camaro. And Chrysler-Plymouth was putting even bigger engines in their performance cars. The 427 engine was available but it was a very expensive upgrade costing an extra $622 then, the equivalent of $5000 today. Tasca Ford turned to drag racer Bill Gilbert for help. Gilbert called a buddy at Ford and learned the the magic of the 427 was the heads. And he found out the 427 heads would not fit on the 390 block. Tasca ordered a 428 Police Interceptor short block from Ford. Gilbert used a bit of creative modifications and got the 427 heads to work on that 428 block. The pistons had to be notched for the larger valves. Gilbert got his Ford friend to order a special cut cam for this combination. He put an aluminum dual plane hi-rise intake topped with a 735 Holley. They put that engine into a 67 Mustang with a C-6 transmission then took it to the track. It worked.
Bob Tasc Sr. drove the Mustang to Detroit to show Ford what they had come up with. Ford kept the 428 to examine it. They replaced the 428 hybrid with a 427 engine from the GT 40 LeMans efforts so he could drive the Mustang back to Rhode Island. In the meantime, Hot Rod magazine ran an article on the Tasca project. Pretty soon tons of Ford fans were sending copies of the article into Ford wanting to order the engine. To read the full articles on Hagerty’s web page, click here or read from the 428CobraJet Registry about Bill Bar, an engineer at Ford, that was involved with the Ford side of the Cobra Jet engine by clicking here.
 | 428 CJ/R & SCJ/R "Q" 4V 1968-1970 (R=Ram Air) | 428 "Q" (1966-68) 428 "P" (1966-70) (P=police engine) |
|---|---|---|
| Engine Type | 8 cylinder 90 degree, Overhead Valves (OHV) | 8 cylinder 90 degree, Overhead Valves (OHV) |
| Displacement | 428 cu.inches (CID) | 428 cu.inches (CID) |
| Maximum torque | 440 lbs./ft. @ 5,400 RPM | 362 lbs/ft. @ 2,800 RPM ("Q" series) 459 lbs./ft. @ 3,200 RPM ("P" series) |
| Maximum Horsepower | 335 BHP @ 5,400 RPM | 345 BHP @ 4,600 RPM ("Q" series) 340 BHP @ 5,400 RPM ("P" series) |
| Bore & Stroke | 4.132" X 3.984" | 4.132" X 3.984" |
| Compression Ratio | 10.6:1 (1968-69) 11.01:1 (1970) | 10.5:1 |
| Mains | 4-bolt | 4-bolt |
| Carburetor | Holley 4150-C (4V) | Autolite 4100 (4V-1966-67) Autolite 4300 (4V-1968-70) Holley 4160 (2x4V- 1967 Shelby GT 500) Holley 4150 (4V -1968 Shelby GT 500) automatic choke all |
| Size of Carburetor | 735 cfm Holley | |
| Fuel | premium gas | premium gas |
| Intake Manifold | cast iron aluminum (Shelby only) | cast iron (all after 12/1968 except Shelby) aluminum ("P" thru 12/1968 & all Shelby GT 500) |
| Valve train | hydraulic lifters | hydraulic lifters |
| Intake | 2.082"-2.097" | 2.022"-2.037" |
| Exhaust | 1.645"-1.660" | 1.551"-1.556" |
| Distributor | single point (1968-69 all, 1970 auto only) dual point (1970 4 speed only) | single point vacuum advance dual point (mechanical advance 1967 Shelby only) |
| Spark Plugs | Autolite BF-32 | Autolite BF-32 |
| Long Block Weight in lbs. | 610 (with cast iron intake) | 560 |
| Emission Controls | Thermactor | Thermactor (all 1968-70 & California) |
| RPM Rev Limiter | 6,050-6,150 RPM (1970 4 speed only) | |
| The 428 Cobra Jet, introduced April 1968, was a high torque, quiet, and inexpensively built engine. Not intended for true racing durability, it lacked the bottom end features of the side-oiler 427. The cross-bolted main bearing caps and oiling improvements were missing. The thin cylinder walls of the 427's 4.23" bore made normal assembly line production impossible. The smaller bore of the 428 was well within normal production line capabilities. The longer stroke (3.98 vs. 3.78 for the 427) gave the engine powerful low-end punch. The 428 CJ and SCJ blocks have extra main bearing webbing and thicker main caps than the normal 390 or 428. The 428 CJ cylinder heads featured an un-machined chamber of 73-76cc, 2.06" intake valves and 1.66" exhaust valves. The intake ports measured 1.34" x 2.34". Exhaust ports measured 1.28" x 1.84". The 16-bolt pattern exhaust face
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