Mustang MonthlyHow To Engine
428 Cobra Jet Engine Detailing, Part 2
The most comprehensive guide to detailing a 428 Cobra Jet ever published
Last month, we brought you Part 1 of 3 on how to detail a 428 Cobra Jet engine to concourse level, with Marcus Anghel of Anghel Restorations in Scottsdale, Arizona. Here we present Part 2, and next month we’ll bring you Part 3. So if you missed Part 1, go back and now and check it out (Hard Core Resto Tech: Detailing a 428 Cobra Jet Engine Part 1) as a refresher/introduction.
This story was originally done in the March 1994 issue of Mustang Monthly, by Bob Perkins, and was one of the most thorough detailing articles written on the subject. That article, like so many others of that time, was mostly with black-and-white photos, so here we will update that—plus add some more in-depth detailing items. Although not every single option and feature can be shown in this story, this guide should serve as a good basis for some of the common detailing tips and tricks.
1. All Cobra Jet engines used a 735-cfm Holley carburetor originally from the factory. Refer to the chart for exact numbers and applications. This information would be stamped in the air horn in front of the choke plate. Date codes would also be stamped in the same area and are decoded in a year/month/week format. Example of 074 would decode as 1970/7th month/4th week. Note that for the months 0=October, A=November and B = December. There also would be an aluminum ID tag that is typically mounted on the passenger side of the carb on the choke assembly. Front metering block would be stamped and identified with a 5673, and the rear metering block would be identified with a 5671.
|Model Year||Engineering Number||Holley List #||Transmission AC|
|1970||DOZF-9510-AA||4513-1||Manual without AC|
|1970||DZOF-9510-AB||4514-1||Automatic without AC|
|1970||DOZF-9510-AC||4515-1||Manual with AC|
|1970||DOZF-9510-AD||4516-1||Automatic with AC|
1a. The early 1968 1/2 carburetors had a unique feature in that they had three locating pins around the air cleaner boss and mounting surface. You can see in the photos below what these look like on these rare carbs.
2. The motor mounts that attach to the engine block are a bare metal finish. The rubber insulators would be painted black and could have a yellow ID stripe on them—especially the service replacement DIZA versions we see today. Original C8 mounts would have a red stripe on them. The ’69 and ’70 convertibles used a different rubber insulator as specified in the parts books.
3. The oil pans used on the Cobra Jets have beveled edges at the rear of the oil pan, as shown here. This gives extra clearance that is needed for the center link and tie rods and power steering ram. Date codes are typically on the bottom with a FoMoCo stamping as well.
4. Original oil dipstick tubes are unique with the spot welds that they have for the attaching bracket and also with the FoMoCo that is stamped on that bracket as well. These would be painted blue with the engine.
5. BF32 Autolite spark plugs are what Ford used on these engines originally. Spark plugs with a star on them were typically only seen until 1968. Later versions did not have this star.
6. The ported vacuum switch that is mounted in the thermostat housing was a C8AE-A version for 1968 and 1969 and a D0AE-A for 1970. The change over date was approximately Aug./Sept. 1969. Date codes are a month/year format with the middle character representing the manufacturing plant—H for Hanover, Illinois, and K for Kalamazoo, Michigan. Note that the switch was installed on the engine when it was painted so it could have some overspray on the lower section.
7. There were several different alternators that were used on the Cobra Jet engine as identified by the chart above. Most variations are with a 55-amp output. Main features to look for and identify in the housing is the AUTOLITE cast into the back as shown, although some of the early 1968 cars would have this case without the AUTOLITE. The alternator cases themselves were ink-stamped with the engineering number until about February 1969. When they were ink-stamped you would typically see two of the same ink stampings on the case in different positions. The color of the ink stamp helped to identify them as well with orange for 42-amp and red for 55-amp. After February 1969 the engineering number was die-stamped into the housing after the matched color was put there, resulting in the letters and numbers not being painted over, as shown. This was done to make it easier to read. Fan blades for the alternators changed as well, with the 13-blade being used until about November 17, 1969, and then the 10-blade being used after this. This was done because the 10-blade design was less noisy than the 13-blade design.
|Year||Application||Amperage||Engineering Number||Pulley Single or Double Groove|
|1968||GT500 and GT500KR||42||C6AF-10300-C||Double|
|1968||AC no PS||55||C6TF-10300-E||Double|
|1968||AC and PS||55||C6TF-10300-F||Single|
|1969||w/o AC and w or w/o PS||55||C9ZF-10300-B||Double|
|1969||w PS and with AC||55||C9ZF-10300-C||Single|
Die-stamped (left) versus ink-stamped housing (right).
7a. The double sheave pulleys changed from the 1968 to 1969 model year. The pulley used in 1968 was the C5AF-10A352-J2 and can be stamped on the front or back of the pulley. In 1969 this changed to the C9AF-10A352-C, which is always stamped on the front face.
8. Note the thermostat bypass hose and clamps are painted with the engine, while the water pump inlet is not. This is a commonly overlooked detail on many restorations.
9. There are a few different distributor vacuum advances that were originally used on the Cobra Jets as shown above. Version 1 was used for four-speed cars in 1968 and 1969, with its most distinguishable features being the silver band and the HP 6 stamped in the top. Version 2 was used on four-speed cars in 1970 and had a gold band and the stamping X6 stamped in the top. Version 3 was used for all automatic cars from 1968 to 1970 and is cast on the backside with the numbers 12378 and AUTOLITE. There was also a design change that happened with Version 2 around Oct./Nov. 1969 in which the vacuum hose connector on the front changed from a screw-in style to a pressed-in style, as shown.
10. Carb spacers used for 1968 and 1969 are a C8AZ-9A589-G and have no identifying marks except the word FRONT that is stamped into the tab on the front. In 1970, the design change added a rear port for the PCV system to attach the hose and changed the part to a D0OZ-9A589-A. There are no markings on the 1970 version.
11. The original thermostat housings are easily identified by the engineering number cast on the front side, which is a C8AE-8594-E. There is also a date code that would be stamped in the circle area to identify the year and month of manufacture. Another way to identify them is the dimple cast in the elbow area, as shown.
12. Oil sender units were different for cars with and without an oil pressure gauge. For those cars with an oil pressure gauge they had a zinc dichromate bulb type sender, while cars without a gauge had a green top oil sender, as shown here.
13. All Cobra Jets used the same aluminum timing cover that would be identified with the engineering number C8AE-6059-B. In addition, these are also all date-coded with a year/month format, as shown here (June 1969).
14. All Cobra Jet engines shipped in the United States had a Thermactor system (commonly called a smog system) to help reduce emissions. The heart of the Thermactor system is the air pump (or smog pump). These are all date-coded and can be easily seen on a Cobra Jet engine once installed. Date codes are read in a year/month/day/shift format. Originals here had a pressure relief valve on the side of the pump and later ones do not. The only other identification for these is the casting number stamped on the back housing, which is 7801149.
14a. Visually one of the easiest components to spot is the air bypass valve assembly (or diverter valve). Originals will say CARTER and ST LOUIS, MO on the front, and FoMoCo on the back. A date code and engineering number will be stamped in the housing as well, although this can be underneath.
14b. The smog tubes shown here are the left and right side and thread directly into the heads. Note these originals and how uneven the paint coverage was, with runs from when originally installed when the engine was painted Ford Corporate Blue.
14c. The mounting brackets used for the smog pump are shown here and consist of two brackets that would have been painted black. The larger bracket is also used as part of the alternator mounting and has an engineering number of C8AE-10156-A. The adjusting bracket was stamped C8AE-B. This is the same for all years.
14d. Smog pump clamps that were used are identified as three No. 7 Wittek clamps, one No. 9 Wittek clamp, plus typically two tower clamps on the S hose. The photo here shows the exact position of the clamps, as per the assembly manual. This was what was shown, but could have varied on cars. Clamps would be a zinc dichromate finish. The No. 9 clamp was used on the canister bracket connection.
14e. Note the small washer that is placed behind the smog pump adjusting bracket as a spacer. This was used on all cars except those with A/C, since they had an additional bracket that takes up that extra space. If the spacer is missing the smog pump will not line up properly.
14f. The short smog hose (left check valve inlet hose) was marked differently for 1968 as a C8OE-9B466-C engineering number. This changed in 1969 and 1970 as the hose was marked as a C9OE-9B466-A, as shown. These hoses were date-coded and can be seen in the lower picture, as the 09288 would be decoded as September 28, 1968. The hoses had a smooth texture and were not actually serviced as such. Parts books indicate to simply cut a length of hose from C8OZ-9B466-C, as this was similar enough.
14g. The long smog hose (right check valve inlet hose) would be marked with a C8OE-9B466-F engineering number and is also date-coded.
14h. The S hose (air bypass valve inlet) was marked with engineering number C8AE-9F287-A and was typically installed with two tower clamps, but also could have one Wittek band clamp, as shown.
14i. Shown here is the most common smog pump pulley used for all cars from 1968 to 1970, marked as a C8AE-9C480-A. The only exception to this is cars with A/C. In 1968 they used a pulley marked as C8AE-9C480-B and in 1969 and 1970 they used a pulley marked as C9OE-9C480-A. These pulleys had a wider groove in them to accommodate the wider belt needed to run with the A/C compressor (JC belt).
14j. Shown here are original service pieces for the nut and ferrule assemblies and the tubes that were used in the ports of the heads for the smog pump system.
14k. The system used two check valves with one mounted on each side with each smog tube assembly. Original check valves have the FoMoCo stamping on them, as shown.
15. The oil dipstick came in two different versions. The C7OE-6750-A version was used until May of 1970. After that, when a TSB was released, new oil levels were recommended and the DOOE-6750-C version was used. Note the dipstick handles—the replacement style has a
16. The original fuel filter used on all Cobra Jets was a C70E-9155-A. Notice the original paper sticker that is still in place to help identify this part. Reproductions of the sticker can be purchased today, and it is a nice detailing touch.
17. There were two different starters used. 1968 and 1969 engines used a C8AF-11001-A and 1970 engines used a DOTF-11001-A. These are date-coded as well with the example here being January 6, 1969. The starters would be painted black except around the drive end and the bolt and hardware to attach the starter cable.
18. The starter wire is routed down under the engine at the engine mount with a single loop to hold it in place and away from the exhaust manifold. Note the protective sheathing as well.
19. The engine ground wire for 1968 and 1969 was on the back of the engine and connected to the firewall, as shown. In 1970 this changed and was part of the negative battery cable. The tab connects to the voltage regulator, as shown.
20. The negative battery cable is typically secured with a plain, unmarked bolt, as shown.
21. The original upper and lower radiator hoses had a unique “snakeskin” texture. The upper radiator hose could be marked with either a Mustang or Cougar engineering number as C8ZE or C8WE, and the lower radiator hoses are a C9OE. The AY was the manufacturer ID for Firestone. Notice the spring clamps are held in place with staples to keep them in place during installation. In 1968 tower clamps were used.
22. The heat shield and snorkel were painted blue but could be a different shade than the engine. Attaching hardware is shown at the exhaust manifold and the front.
23. Two different breather cap elbows were used. In 1968, a metal elbow was used and then changed to a black plastic elbow, as shown here. The original chrome breather caps had the word AUTOLITE stamped in them; that is visible on the top surface when installed on the valve cover.
24. Original breather hose from the breather cap to the air cleaner assembly were date-stamped. This one shown here is stamped 10289, which is October 28, 1969.
Come back next month for Part 3 of How to Detail a 428 Cobra Jet!
A special thanks to those fellow enthusiasts who have helped here with their knowledge and photos and ideas…including of course Bob Perkins for his years of experience, patience, and guidance; Jim Woods for his great collection of photos; Jack Brooks for all things concerning alternators; Scott Fuller for his collection and photos of 1968 cars; Dave Lochhead for his collection of N.O.S. parts; Kerry Wortman for his years of research on engine block decoding; Bob Gaines for photo contribution; Chris Teeling and Scott Hollenbeck for their work with the 428 Cobra Jet site; and many others in the Cobra Jet community.