Intake Manifold

The most common intake manifold used for both 428 Cobra Jet and Super Cobra Jet engines from 1968 through 1970 is easily identified. It's a cast iron, 4v dual plane design that carries engineering number C8OE-9425-C. According to Chris Teeling, some early 1968 CJs came equipped with an intake carrying engineering number C80E-9425-A. Chris says "The -A more resembles a 428 PI intake casting. The size of the engineering numbers are much larger and there is "XE" number on the #1 runner which is partially ground off" (more on the -A intake below).

The engineering number can be found towards the back of the manifold, just behind the carburetor mounting area as shown in the picture on the left below. The casting date can be found just a little further towards the back of the manifold as shown in the picture on the right below. Those holes just to the above left of the casting date are used to mount the accelerator cable bracket.

C8OE-9425-C engineering number detail.Casting date detail, 9K2 (October 2, 1969) shown.

This intake manifold, like all FE intake manifolds, is a "wet" (coolant flows through it) intake that extends under the valve covers when installed. In the picture below you'll notice holes above the intake ports for the push rods, intake ports, and passages for engine coolant.

Aluminum 428 Police Interceptor (PI) intakes are a popular replacement since they interchange readily and weigh a whole lot less (about 25 pounds) than this 75 pound cast iron monster! However, they are not original to regular production 428 Cobra Jets.

1969 and 1970 owners take note: your intake manifold was bolted down with bolts that included studs for mounting accessories. All 1969 and 1970 CJs have a studded bolt in the third mounting hole on the driver's side of the intake that was used to mount a bracket for the shaker hood scoop. Even Q-code cars should have this studded bolt because the engine assemblers didn't know if the engine would be going into a Q-code car or an R-code car when the engine was assembled. 1970 cars used a second studded bolt in the second bolt hole from the front on the driver's side that was used to mount the rev limiter ground wire.

Intake Manifold Variations

by Chris Teeling

There were three different intake manifold castings installed on 428 Cobra Jet engines during their 2 ½ year production run. These were the aluminum 428 Police Interceptor (PI) intake C7AE-9424-F (casting number C7AE-9425-F), the first production 428 CJ intake C8OE-9424-A (casting number C8OE-9425-A), and the final 428 production intake C8OE-9424-C (casting number C8OE-9425-C). There is no evidence that a C8OE-9424-B intake was ever produced.

The PI intake was only installed on the 50 "135" Mustangs. This occurred because they were part of the 428 PI engine bill of materials which was used as the basis for the batch of engines built for these cars. Ford planning documents show that their intent was to use the initial 428 CJ intake but changed plans due to a design delay so they reverted to the PI intake. Evidence of this is a Ford Engine and Foundry add and delete list written on December 1, 1967. This list contains materials planning instructions for the "135" engines. The "Add" column of this document states "To follow" with "C7AE-9424-F" under "Delete". A note under "Part availability" states "PEO (Production Engineering Office?) to release add part". This shows that the 428 CJ intake manifold had not yet been released for production. Whatever held up release of the C8OE-9424-A manifold took some time to resolve as the earliest casting date we have seen is February 22, 1968.

The -A 428 CJ intakes were cast at the Cleveland foundry and, after machining, installed on early vehicles produced in March and early April 1968. They appear to have been cast using temporary tooling as evidenced by their rougher surface finish, the left over development change letter -AN tag dated 7-24-67, as well as the casting number tag being nailed to the mold.  Production of this manifold continued through early April when it was superseded by the -C manifold.

Top view of C8OE-9424-A Intake Manifold

Nailed-on Change Letter TagsNailed-on Casting Number Tag

The form of the top of the -A intake do not appear to be different than the later -C manifold however the exhaust crossover of the -A intake is considerably different and more closely resembles the PI intake.

Bottom View of C7AE-F IntakeBottom View of -A Intake    Bottom View of -C Intake

The second production 428 CJ intake manifold was the C8OE-9424-C. This manifold was cast at the Cleveland Foundry beginning in late March 1968. This manifold was cast using new production level molds which resulted in a better surface finish and production style screw on tag attachments. Ford documents show that there was a change to the iron composition, a change to the exhaust crossover, and a 0.10 inch diameter reduction in the throttle bores made at about the same as the -C manifold was introduced. Although the casting number was not revised, a boss was added to the top of the manifold at the intersection of the number 1 and number 6 ports in the fall of 1968. The first picture is of an early 1969 –C manifold that has an 8H7 casting date. Compare the top of the #1 runner to that of the later –C manifold shown below. This manifold has a casting date of 9A22.  It is a minor detail, but you can see the additional boss at the intersection of the #1 and #5 runners (circled in red).

Early -C ManifoldLater -C Manifold