Frequently Asked Questions

Some questions seem to get asked over and over again. Hopefully this list of answers to "frequently asked questions" will be helpful.
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428 Cobra Jets and Super Cobra Jets used the exact same induction systems and cylinder heads. What makes a 428 Super Cobra Jet unique is the specialized reciprocating assembly.

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Contrary to most published literature, documentation describing the Detroit Locker doesn't appear from Ford until approximately November 1969, which is well into the 1970 model year. Earlier documentation that I've seen, such as original invoices, clearly describes the "W" code differential as a "Traction-Lok" differential. This is an ongoing research area, and it would be very helpful if anyone who might have documentation describing an original Detroit Locker installation in a 1969 Mustang could share their insights. See the CJ vs. SCJ page for details.

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Starting in 1969 Ford began offering an optional 3.91:1 gear ratio that used Ford's Traction-Lok differential, which used a clutch pack for quiet, streetable rear wheel locking under hard acceleration in a straight line. Order this option and you also got a 428 SCJ engine!

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In late December 1967 (date code 30M), Ford produced 50 Wimbledon White sportsroof Mustangs with black vinyl interiors for drag racing duty. The vehicles were numbered sequentially, starting with VIN 8F02R135007 and ending with VIN 8F02R135056.

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Starting in 1968 Ford began stamping partial VIN information on a pad just under the back of the driver's side cylinder head of all factory-installed 428 Cobra Jet engines to comply with Government-mandated regulations. Partial VIN stamps have also been found on cylinder heads in the area just above this pad. Service blocks didn't receive VIN stampings, so as engine swaps have taken place over time it has become very difficult to keep up with this "matching numbers" reality. Once an engine is installed it's practically impossible to see this stamping even if it does exist! Ford also stamped partial VINs on transmission cases, so take a peek at when you next have a chance.

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According to Ford production records researched by Kevin Marti, Ford produced eleven 1970 Mach 1 Mustangs with a 428 CJ engine, 4-speed transmission, and air conditioning. All were produced fairly late in the model year, with eight produced at Dearborn, one produced at San Jose, and two produced at Metuchen. Five of the cars were Q codes, and six were R codes. All were equipped with 3.25:1 rear gears; two were limited slip (code "R") and nine were open (code "9"), and only one was equipped with a factory tachometer. All eleven of the VINs are known to the registry, but the location and condition of some of these cars is still a mystery. There are many written reports that describe how air conditioning couldn't be ordered with a 428 CJ and 4-speed transmission in 1970, but towards the end of the model year Ford definitely let a few slip through.

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Kevin Marti confirms that the records his company has licensed from Ford do not include any 1968 Mustangs equipped with a "Q" engine code. The VINs I've seen for alleged Q-code cars have all turned out to be cars that originally left the factory as C-code (289-2v) cars, meaning someone modified the cars and altered the VIN - and that's not legal.

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Finding the word "Super" stamped on some Cobra Jet blocks has led some people to believe that the block is a high nodular iron casting or is somehow otherwise stronger than other 428 Cobra Jet blocks. According to several sources all 428 Cobra Jet, 428 Super Cobra Jet, and 428 Police Interceptor engines were assembled on the same production line and this stamping helped identify engines whose bottom ends required Super Cobra Jet components.

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There is no perfect answer to this question. Value is very much a matter of condition, original equipment, race history, and where you live. A rust-free car will always be worth more than a rusty car if all else is equal, and a car missing original equipment will always be worth less than a car that's complete. If you want to get a feel for worth you might try looking at the classified ads in Hemmings Motor News, or check out national auction results in the magazines that publish such info.

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Please note that there is no complete registry listing published on the registry web site. There is a photo gallery of member vehicles, but registering your car doesn't get your car listed in the photo gallery -- you must create your own gallery entry. Instructions for creating a photo gallery page can be found on the gallery info page.

We have published a registry book containing information for every car that's been registered. Rest assured that your car is included in the registry once you've sent in your information.

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Ford did not install a rev limiter during the 1968 and 1969 model years. In 1970, Ford added an electronic engine RPM limiter/governor to Mustangs equipped with 428 Cobra Jet engines and 4-speed transmissions. These units limited spin up to 5,800 rpm in an attempt to keep warranty claims to a more manageable level. Fortunately (or unfortunately, depending on how you look at it), removal was quite easy and a great many of these units have failed to remain attached to the cars they were originally installed in.

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Contrary to most published literature, 428 SCJ engines were originally equipped with cast pistons. Some of the confusion may be because of the later 429 Super Cobra Jet, which was originally equipped with forged pistons. See the CJ vs. SCJ page for details.

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428 Super Cobra Jets were available both with ram air induction (identified with VIN engine code "R") and with a standard air cleaner assembly (identified with VIN engine code "Q"). The engine code isn't what determines installation of a Super Cobra Jet engine; it's the rear end codes of "V" (3.91:1 Ford traction-lok) or "W" (4.30:1 traction-lok or Detroit Locker) that make the difference.

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The 428 Super Cobra Jet engine was first available in 1969, exclusively available when ordering either of the optional 3.91:1 or 4.30:1 rear end gear ratios. The Super Cobra Jet included a number of reciprocating assembly changes to stand up to the rigors of drag racing, including beefy capscrew connecting rods, cast pistons, and a crankshaft, flywheel or flexplate, and harmonic balancer distinct from the standard 428 Cobra Jet. An external engine oil cooler mounted in place of the driver's side horn (the horn gets relocated to the passenger side) and the distinct balancer with counterweight are the only visible clues to what lies within.

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While it's true that most 428 CJ carburetors used an automatic choke, the 1970 carburetors used a manual, cable-activated choke. These carbs can be identified by casting numbers D0ZF-9510-AA (4-speed without air conditioning), D0ZF-9510-AB (automatic without air conditioning), D0ZF-9510-AC (4-speed with air conditioning), and D0ZF-9510-AD (automatic with air conditioning).

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While it's true that most 428 CJ distributors used a single set of points, the distributor used for 1970 4-speed applications was a dual point, dual vacuum advance distributor. This distributor can be identified by casting number D0ZF-12127-C.

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Despite rumors to the contrary, probably not. We have confirmed that the earliest known 1969 R-code Mustangs were indeed equipped with "Shaker" air cleaners.

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Check out the links page and the classifieds section of the registry forum for pointers to trustworthy vendors and other online parts sources. You can also look at Hemmings Motor News.