Few things determine an engine’s personality more than cylinder heads, camshafts, and rocker arms. Ford V-8s have always struggled to make power because they’ve always been limited by factory cylinder head design. Port size on small-block Fords has always been a shortcoming, even with the 351C and Boss 302 with huge ports. Huge ports can hurt power as much as ports that are too small. When ports are too large, they limit low- to mid-range torque. This doesn’t help much on the street, where these engines spend most of their time.
If you must use stock cylinder heads, selection is modest for Fords, but you do have some options. It is wise to go for the best heads for your application. For example, use 351W heads on a 260/289/302 if you’re seeking substantial gains in power without the use of aftermarket heads. And, if you want to improve your odds, go with CNC-ported 351W cylinder heads from PowerHeads of Southern California. These cylinder heads are affordable and you can make the most of stock iron castings without having to sell the farm.
Small-block Ford cylinder-head identification is straightforward if you know what to look for. In time, it becomes second nature. The most important clues are Ford casting numbers and date codes, and understanding the difference between a casting number and part number. Rarely are the two ever the same.
This Tech Tip is From the Full Book, HIGH-PERFORMANCE FORD ENGINE PARTS INTERCHANGE. For a comprehensive guide on this entire subject you can visit this link:
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The 221 cylinder head is identifiable at a glance by observing its small kidneyshaped 45- to 51-cc combustion chambers along with 1.59/1.39-inch intake/exhaust valves. These heads are casting numbered C2OE or C3OE and are identical in appearance. The 260 heads have larger 52- to 55-cc kidney-shaped chambers with the same valve size. Expect to see C2OE-F, C3OE-B prior to February of 1964. In February of 1964, Ford came out with an improved 260 head with larger 1.67/1.45- inch valves along with the same 52- to 55-cc chambers. The revised head is numbered C4OE-B.
The 289 head was produced in several casting types beginning in 1963. Like the 260 head, the 289 has compact 52- to 55-cc chambers with a more recessed spark plug. Valve size remains the same as the 260. The 289 head casting numbers were typically C3AE-F, C3OE-E, C3OE-F, and C4AE-C in 1963–1964. Casting numbers evolved to C5DE-B, C6DE-G, C6OE-M, C6DE-C, and C6DE-E. The C6DE-C and C6DE-E heads are Thermactor smog system castings and not of much use unless you are performing a restoration on a 1966 Ford or Mercury originally fitted with this emission-control system. These Thermactor smog head exhaust ports, which are very restrictive, can be hogged out for performance use, but there’s a lot of port work involved and it costs more than it’s worth.
Beginning May 2, 1966, Ford changed both cylinder heads and valvetrains on 289 engines. Prior to this date in production, Ford had pushrod guide holes machined into the castings. However, from May 2, 1966 on, Ford found a cheaper way to make 289 engines. It eliminated a cylinder-head machining step (pushrod guide holes) and used railstyle rocker arms. Rocker arm rails keep rockers centered on longer valvestems. Although this saved Ford a bunch of money, it was a lousy idea because railstyle rocker arms aren’t acceptable for performance applications. In fact, railstyle rocker arms are a bad idea in general because, as the rocker wears, rails become closer to the retainer. This puts your engine at risk for valvespring retainer failure. Cylinder heads designed for railstyle rocker arms are casting numbered C7OE-A, C7OE-B, C7OE-C, C7OZ-B, and C7ZE-B from mid 1966 through 1967.
For 1968, casting numbers to look for are C8OE-D, C8OE-L, and C8OE-M for the 289, which employ larger combustion chambers for reduced compression. Despite changes in chamber size, these heads are virtually the same as previous castings except for the machinedin provisions for the Thermactor smog system. The main thing you want to watch for is valve and combustion chamber sizing. Another difference for 1968 is positive-stop rocker-arm studs, which are not adjustable. Just slowly run them down to the stop, and that’s it.
The 289 High Performance cylinder head is a unique casting with cast-in valvespring pockets and screw-in rockerarm studs. These features help maintain valvetrain stability at high RPM, which make them appealing for highperformance applications. But, you don’t need 289 High Performance cylinder heads to get the same result. Your machine shop can install screw-in rocker arm studs, pushrod guide plates, and valvespring cups for the same end result. Valve and port size is identical to 289-2V/4V heads. The 1967 289 High Performance head has slightly larger ports with the same valve size.
The 289 High Performance head to look for is the C3OE, which is the 1963 head casting with smaller 49.2-cc chambers for higher compression. The downside is this head also has smaller valves (1.67/1.39 inches), which can be increased to 1.94/1.60 inches to improve performance. Beginning in 1964, Ford increased valve size to 1.78/1.45 inches. Combustion chamber size increased to 54.5 cc for 1964 along with the larger valves just mentioned. The numbers to look for here are C4OE-B, C5OE-A, and C5AE-E. Despite the 289 High Performance head’s reputation for rarity and value, there are better aftermarket heads out there if you want real performance. When originality is important, there’s no substitute for the Hi-Po head, which tends to be quite expensive because there aren’t that many for sale out there. However, if performance is your goal, don’t waste your money on a Hi-Po head. There are better heads out there that offer so much more.
Despite the 302’s close relationship with the 289, there is some difference in cylinder-head castings. The elusive 1968 302-4V head is unique for its smaller 53.5-cc chambers, which increase compression.
Compression is this cylinder head’s only advantage. This makes it a good cylinder head for any 289/302 Ford if you want to pump up the power a bit. Otherwise, the 4V head has the same size valves and ports as the 289. The 302-2V head for 1968 has larger 63-cc chambers to lower compression and reduce emissions. Look for C7OE-C, C7OE-G, C8AE-J, C8DE-F, C8OE-J, C8OE-M, C8OE-K, and C8OE-L. Like the 289 heads mentioned earlier, all 302 heads are the same except for Thermactor provisions. There’s also a truck head (C9TE-C), which employs a 58.2-cc chamber for slightly higher compression. Ultimately all 302 heads were carryovers of the 289 head, making them all interchangeable.
When it comes to interchanging cylinder heads, the most important issue is chamber size and its effect on compression. As time passed with these engines, chamber size got larger, further reducing compression ratio for use with lower-octane, low-, or no-lead fuels. Be mindful of this fact when you’re scouting for cylinder heads. Most 302 heads in the 1970s had 58-cc chambers along with the same port size and 1.78/1.45- inch valve sizes. Numbers to watch for are D1TZ A, D5OE-GA, D5OE-A3A, and D5OE-A3B. Beginning with the D5OE head, Ford did away with those Thermactor manifold bungs and went to a common internal air-injection manifold that ran the length of the head and didn’t cause exhaust-port restriction.
Beginning in 1977, chamber size increased to 69 cc to further reduce the 302’s compression ratio. These heads are numbered D7OE-DA and D8OE-AB, which are not desirable castings no matter what you do with them. In 1979, Ford came out with a D9AE 302/351W cylinderhead casting, which was very similar to the D7OE and D8OE castings just mentioned with 67- to 70-cc chambers. The D9AE-6049-AA casting was in production until 1985. When Ford went to roller tappets and a new 5.0L roller block in 1985, it also came out with a new E5AE-6049-CA head casting designed to clear roller tappets, making it possible to replace these lifters without removing cylinder heads.
For 1986, Ford went with the E6AE-6049-AA casting with “high-swirl” chambers. This is the head Ford used on the 1986 5.0L High Output V-8 with Sequential Electronic Fuel Injection (SEFI). For 1987, cylinder-head selection changed again with two types involved: the E7TE-6049-PA head (with fast-burn chambers), and existing stock of the E5TE-6049-PA (truck head). The E7TE- 6049-PA head was the most common casting used through 1995.
The 1993–1996 GT-40 cylinder head, F3ZE-6049-AA, used in the Mustang SVT Cobra and Lightning F150 pickup, was a modest improvement over the E7TE-PA casting thanks to smaller 60–63-cc chambers and larger 1.84/1.54-inch valves. It can be identified by the three vertical ribs cast into each end of the cylinder head. Sometimes, there’s “GT” cast into the same area. The F3ZE-AA head evolved into the F4ZE-AA service head for 1994—virtually identical in appearance. The GT-40 head is a good budget casting because Ford cast this head for the Mustang and for Ford Motorsport SVO, Ford’s aftermarket performance parts group, as M-6049-L302. These plentiful heads are all over the swap meets.
When the 5.0L High Output engine stubbornly hung on in the Ford Explorer and Mercury Mountaineer in the late 1990s and early 2000s, Ford produced a rather odd-duck cylinder head designed to reduce emissions while boosting power for this engine. This head is known as the GT-40P or “P” head (F7ZEAA) designed specifically for Explorer/ Mountaineer. The “P” head has a reduced spark-plug angle, where the firing tip has been moved closer to mid chamber. Intake valve size is the same as a GT-40 at 1.84 inches. However, exhaust valve size is smaller at 1.46 inches. The problem with this cylinder head is using it in anything but an Explorer/Mountaineer because the spark-plug angle presents header and exhaust manifold clearance issues.
If ever there was an odd engine in Ford history, it was the 255-ci smallblock in 1980–1982. Ford de-bored the 302 and kept the same 3.000-inch stroke to achieve 255-ci and improve corporate average fuel economy (CAFE). The 255 head (E0SE-AB) with its 53- to 56-cc chambers and 1.68/1.46-inch valves is a unique piece with small, restrictive port sizing to improve emissions. It is not a suggested cylinder head for performance use.
Because the 351W employs a larger displacement, it has larger ports and valves than its 289/302 counterparts. This makes the 351W head a great performance modification for the 289/302. And if you’re building a 351W, it’s important to know which head castings are best for your application. The best 351W head castings are C9OE-B, C9OE-D, D0OE-C, D0OE-G, D0OE-C, or the D5TE-EB truck head. All of these castings employ the same 60.4-cc chamber along with 1.84- to 1.54-inch valves. Beginning in 1978, the 351W chamber grew to 69 cc, resulting in lower compression. The number to look for here is D8OE-AB— the head to avoid. The D8OE-AB casting is basically a 302 head with smaller 1.78/1.45-inch valves. Ford went to smaller valves for improved emissions and better low-end torque. As 351W production moved into the 1980s, cylinder heads didn’t change much, with castings following the 302’s path.
When Ford did those limited-production SVT Lightning F150 pickups in the early 1990s, their 351W/5.8L engines got the same GT-40 cylinder heads as the 1993–1995 Mustang SVT Cobra.
The 1969–1970 Boss 302 cylinder head is little more than a modified 351C head casting revised for use on a 302 block. The primary difference is cooling passages, because the 351C has a dryintake manifold and the Boss 302 has a wet one. There are three basic Boss 302 cylinder head castings: C9ZE-A with 63-cc chambers and huge 2.23/1.71-inch valves, D0ZE-A with smaller 58-cc chambers and 2.19/1.71-inch valves, and the D1ZE-A service head, also with 58-cc chambers and 2.19/1.71-inch valves. Ford went to a smaller 2.19-inch intake valve with the D0ZE-A and D1ZE-A head castings to improve low-end torque. However, that didn’t help much. Ford’s Boss 302 was never intended to be a lowto mid-range-RPM street engine. It does its best work at high RPM. The Boss 302 head has pushrod guide plates and screw-in rocker-arm studs.
We group these engines together because they’re basically the same engine architecture with the same cylinder head. There are four basic variations of the Cleveland cylinder head. Which head you choose depends on how you use your engine. The 351C-4V head is the most desirable casting out there because it has huge ports and valves, along with high-compression wedge chambers. Look for D0AE-H, D0OE-R with huge 2.50 x 1.75-inch intake ports and compact 61- to 64-cc wedge chambers for 11.0:1 compression. This is a great cylinder head for high-RPM operation because it flows so well and offers extraordinarily high compression. The quickest way to power is raising compression; but keep available fuel octane in mind.
There are two types of 351C openchamber heads: the 2V, and the 4V. Neither is recommended for performance use. A fundamental shortcoming of the 351C open-chamber head is poor quench, which makes these heads prone to pinging or spark knock regardless of how you tune the engine. Under load and with light throttle, you get spark knock. In fact, you can goose the throttle in neutral and get spark knock. The 351C-2V open-chamber head was used from the start in 1970 (D1AE-AA and D1AE-CB) and continued with the 351M and 400M engines. The 351C-4V openchamber head (D1ZE-DA and D1ZE-GA) offers little in terms of advantages because its open-chamber design loses compression and aggravates spark knock. There’s no point in using this head unless you’re doing a concours numbersmatching restoration.
The best cylinder head available for a good street 351C, or even the 351/400M, is the Australian 302/351C head. It sports the smaller 64- to 67-cc wedge chamber with right-sized 2-barrel ports for excellent low- to mid-range torque. Power- Heads is an excellent source for CNC-ported Australian 351C heads. These cylinder heads aren’t always easy to come by, but they’re out there. Edelbrock is producing an Australian-style 351C aluminum cylinder head, which offers lightweight design, good temperature dissipation, and improved flow. This makes the Edelbrock head a nice alternative to the Ford iron head.
The 351C-4V closed-wedge-chamber head (61.3 to 64.3 cc) head makes 11.0:1 compression, depending upon piston selection and compression height. The open-chamber 2V and 4V heads (74.7- to 77.7-cc chambers) net 9.5:1 compression, depending upon piston selection. The 351C-2V head’s advantage is port size on the street. The down side is chamber design and spark knock.
Ford Racing Performance Parts Cylinder Heads
Today, as in 1998 when this book was first published, the broadest selection of aftermarket cylinder heads isn’t from the aftermarket at all, but rather from the factory. Ford Racing Performance Parts and its former name, Ford Motorsport SVO, offer the performance enthusiast a wealth of options. Selection isn’t what it was when this book was first published. Some of these heads are still available from Ford Racing. Others have been discontinued and are available either used or new old stock in their original packaging. The cool thing about Ford Racing aftermarket heads is the ease of selection along with simplicity. You don’t have to search for factory iron castings like 289 Hi-Po or 351W heads anymore. Ford Racing has a cylinder head for virtually every application.
The most common Ford aftermarket head is the GT-40 High Flow available in iron or aluminum. If you want a more stock appearance with factory-like head castings that offer an improvement in performance, this is a good cylinder head. These heads, with good port work, improve horsepower on the high end thanks to 1.84/1.54-inch valves, which can easily be increased to 1.94/1.54-inch (Chevrolet intake valve size). The GT-40’s 65.5-cc chambers are a nice compromise between older 54- to 55-cc and 70+ cc chambers. You can mill this cylinder head’s deck surface to reduce chamber size and raise compression.
Today, the GT-40 Turbo-Swirl cylinder head is now known as the M-6049- X306 and X307 for 289/302/351W engines. The X306 aluminum head has a 64-cc chamber. The X307 head has a 58-cc chamber. The intake ports flow 240 cfm at .550-inch lift. Exhaust flows 170 cfm at .500-inch lift. This head is machined for 1.94/1.54-inch valves. Your pistons must have valve reliefs to reduce the risk of valve-to-piston contact. You must also check intake manifold port compatibility by doing a gasket match. A nice thing about the GT-40 head is its compatibility with just about any intake manifold or header.
The “Z” aluminum cylinder head is a nice alternative to the “Turbo-Swirl” just mentioned, if you’re going to do weekend racing. Made of A356 T6 cast aluminum, the Z head offers improved flow numbers and more power if you give it your best attention. It mandates a competition valve job and bowl work, but you have a CNC-ported head you can buy from Ford
Racing Performance Parts. You get premium stainless-steel 2.02/1.80-inch valves for more horsepower and midrange torque. Beehive valvesprings eliminate valve float. Laser-cut guide plates yield perfect fit. Expect 319.7-cfm intake flow and 227.7-cfm exhaust at .550 inch.
The cast-iron Sportsman head (M-6049-N351) from Ford Racing is a nice compromise between the Z head, GT-40 Turbo-Swirl, and the Yates NASCAR head. It has 2.02/1.60-inch valves for improved flow along with 64-cc chambers. This head is suggested more for 351W engines, but can be used on the 289/302 using a head bolt adaptor kit. It accepts the M-6569-C351 stud girdle. Do some port work on this head and you can make more power.
The Robert Yates High-Port aluminum head is a NASCAR-level race head (M-6049-C3) sporting a tiny 40-cc chamber. It comes bare and you get to choose what goes inside. There’s also the M-6049-C3L Yates head with 67-cc chambers for reduced compression. Huge 2.10/1.60-inch valves occupy both heads. Because this is an all-out race head, it is not suggested for the street. And because it is a race head, expect to make all kinds of modifications.
Camshafts, Lifters, Pushrods and Rocker Arms
A camshaft, along with rocker-arm selection, has a more direct effect on an engine’s performance than any other element because you can control lift via rocker arm ratio and lobe lift. Of course, when you’re talking factory camshaft grinds, there were a lot of them. And unless you are seeking a spot-on factory feel and performance, there’s not much point in going with a factory grind because the aftermarket has a much better selection.
Ford’s original Motorsports program in the 1960s had a broad selection of camshafts that were easy to select from. The following table covers the basics of what was available from Ford in the late 1960s.
Which cam you choose, either Ford or aftermarket, depends on how you intend to use your engine most of the time. The spring pressure and cam profile must be compatible. Not enough spring pressure, you can float valves at high RPM. Too much spring pressure, you wear out cam lobes prematurely. In the good old days, Ford used to market a great concoction called Ford Oil Conditioner (C2AZ-19579-A) in 1-pint cans, which promoted compatibility. Today, you’d call it a zinc additive (such as ZDDP or Cam Guard), which reduces engine wear, especially during break-in.
Today’s camshaft aftermarket offers the greatest selection in performance history, with much better performance than what was available long ago. Although roller cams and rocker arms are expensive, they’re worth every dime for what you gain in performance, efficiency, and wear. Reduced internal friction is everything to power gains. You can run a more aggressive lobe without the struggles of a hot cam. One nice thing about rollercam technology is its invisible status. It’s in there, but no one knows it is. If you’re running a 289 High Performance or Boss 302, you can actually run a hydraulic roller cam and get the same sound performance without having to perform periodic valve adjustment. Much depends on how high you intend to spin the engine. When it comes to high-end performance, there’s no substitute for a hot mechanical roller camshaft.
There were a number of changes in small-block Ford timing set configurations during this engine family’s production life. You must pay very close attention to change levels and make sure everything works well together. There are three basic camshaft thrust plates. The C3OZ-B thrust plate has lubrication slots 180 degrees apart with a 47/64-inch center hole and two 19/64-inch bolt holes. The use of this thrust plate calls for the use of a C2OZ-A timing sprocket. This applies to the 260-2V, 289-2V/4V engines. It does not, however, apply to the 289
High Performance V-8, which accepts a C3OZ-A thrust plate (3/8-inch thick) and a compatible timing sprocket. Smallblock Fords manufactured, after change L7 in 1965, mandates the use of three potential cam thrust plates. They are: C9OZ-A, which is the standard 1/4-inchthick thrust plate; C9OZ-Bat .002-inch oversize; or C9OZ-C, which is .004-inch thicker. These thrust plates are of different thicknesses to take up end play. Three cam sprocket types were available from Ford: C3OZ-C, an iron sprocket for 221, 260, and 289-2V/4V engines; C3OZ-A iron sprocket for the 289 High Performance V-8; and the C5OZ-B, a nylon-coated aluminum sprocket for the 289-2V/4V after change L7 in 1965. The nylon-coated sprocket is strongly discouraged because, although quieter, it is not as durable and fails sooner. Nyloncoated gears were conceived for quieter operation. However, they don’t last and darned if I’ve ever heard a noisy timing set in the small-block Ford’s history, even with iron gears.
Check camshaft end play with the timing gear installed to determine which thrust plate/sprocket combination is right for your engine. If endplay is substantial, the thrust plate and sprocket aren’t the right combination for your engine. A good rule in high-performance engine building is to opt for the dualroller timing set. Dual-roller chains are less prone to stretch. If you’re going with a dual-roller timing set, don’t forget to leave out the crankshaft oil slinger, which can get into the timing chain and do incredible damage. One solution may be to flatten the oil slinger, which keeps it out of your dual-roller chain to where you can still enjoy its benefits. The crankshaft oil slinger serves two purposes: to splash drainback oil onto the timing set, and keep excessive oil away from the crankshaft front seal.
Ford employed three basic types of timing covers on small-block Fords from 1962–2000 and they’re all interchangeable depending on where your engine is going. From 1962–1967, there were two types of cast-aluminum timing covers with cast-in timing pointers. The C4AZ-B (C2OE- 6059-D) cover has a provision for an oil filler tube like you see on some, but not all 1962–1964 221/260/289 small-blocks. It was more common from 1962–1963, though not as common in 1964. If you read the Ford Master Parts Catalog, you find change L8 in association with the C4AZ-6019-B timing cover. With change L8 came the timing cover we’re most familiar with, devoid of the oil filler tube provision. The earliest versions of this timing cover with cast-in pointer were numbered C4AE-6059-B. If you cruise the Ford Master Parts Catalog, suggested part number is D3OZ-6019-A, which is a universal timing cover with a bolt-on pointer used from 1968+ and also used on the 351W. Beginning in 1970, when the water pump inlet was moved to the left-hand side for improved radiator crossflow, the timing pointer was moved to the right-hand side. This change came with a revised four-bolt harmonic balancer.
When 5.0L and 5.8L engines first became equipped with Central Fuel Injection in 1980, Ford employed a timing cover with a timing-light magnetic pickup point on the right-hand side.
Beginning in 1994, Ford went to a reverse-flow cooling system, with a different timing cover and water pump. This combination is easy to identify because the water pump is smaller and the timing cover is designed only for this reverse-flow water pump.
Valves, Springs, Retainers and Locks
The 221 and 260 engines stand alone, when it comes to valvetrain components, for several reasons. Valve size is the smallest of any small-block Ford, with a .310-inch stem, which is smaller than the 289/302’s .342-inch stems. The 351W has the same size valvestem (.342 inch) as the 289/302.
Boss 302 and 351C/351M/400M engines are grouped together because they share the same basic cylinder-head design. Like the 289/302/351W, the Boss 302 and Cleveland engines share the same valvestem size (.342 inch) with larger valve faces. Valvespring keepers and retainers mandate close attention. The same can be said for valvesprings, which should be replaced anytime you build an engine. Valvespring pressures should always be compatible with cam lobe specifications. When you’re shopping for camshafts and valvetrain components, it is suggested you go with the same brand from cam to valvespring in the interest of consistency.
Small-block Ford valve covers have evolved through the years, but overall haven’t changed much since this engine’s debut in 1962. The first changes came on May 2, 1966, when Ford went to the rail-style rocker arm, which called for additional clearance between rocker arm and valve cover. This called for a pentroof- style valve cover that remained to the end in 2000. From 1962–1966, smallblock Fords came with a wraparoundstyle valve cover either with or without an oil filler tube and PCV valve passage. Engines equipped with a timing cover oil filler had closed valve covers.
The pent-roof-style valve cover continued for 1968 with the words “Power By Ford” stamped into the cover. This style remained until 1975, when Ford went to the corporate Ford oval, which continued through the early 1980s when Ford Blue gave way to a new corporate version of battleship gray. With these changes came relocation of the PCV valve to the oil filler cap. With the advent of fuel injection came the rightside valve cover oil filler and closed crankcase ventilation tube. When Ford introduced the 5.0L-2V High Output V-8 in 1982, finned cast-aluminum “Powered By Ford” valve covers came with it, and were used through 1985. When Ford introduced the 5.0L SEFI High Output V-8, with that came ribbed cast-aluminum valve covers with a tall oil filler tube on the right-hand side. When the 1993 Mustang Cobra was introduced with the 5.0L GT-40 V-8, it had black stamped-steel valve covers with a long oil filler tube and a crankcase ventilation tube tied to the throttle body.
The greatest challenge you face selecting valve covers is valvetrain clearance issues. Aftermarket poly locks and rocker arms don’t always clear valve covers. Rocker arm cover spacers are available, as are double-thickness valve cover gaskets from Fel-Pro, which enable you to clear valvetrain components. Scott Drake valve covers have unique oil splash baffles designed to clear all valvetrain components.
Written by George Reid and Republished with Permission of CarTech Inc