- 100% Designed, Tooled, Cast and Machined in the USA.
- A357 T6 Aluminum Castings – T6 heat treated, low silica alloy. Similar in strength, machine-ability and weld-ability to 6061-T6 billet. Superior strength compared to all commercially vailable castings. 20% stronger than similar high-end castings made from A356. A357 is the same material used in most aftermarket engine blocks along with many cast aerospace components.
- 0.750” deck structure, thicker than all stock and most aftermarket castings
- High efficiency water jacket – by increasing efficiency the overall water jacket has been reduced for overall strength without sacrificing cooling ability for all applications including endurance racing.
- Raised runner design on both intake and exhaust – Raised runner design allows for more efficient cylinder filling, better high-rpm operation without sacrificing low and mid-range performance. Greater flow characteristics, especially when combined with our shallow valve angles. Intake flange is extended to allow all standard manifolds to fit without modification.
- Exhaust port exit is on center with valve – Substantially better flow characteristics. LS7 bolt pattern moved to accommodate all standard header designs using 2” or larger headers.
- Proprietary valve cover design – Enlarged valve cover based loosely on a SB2 pattern allows for more rocker clearance when using solid rollers, more spring clearance for larger diameter/higher lift packages. Valve covers included with purchase of heads. See valve cover section below for additional information. Valve covers are doweled and o-ringed for superior sealing and serviceability.
- -6 ORB water crossover ports – better cooling capacity and more flexible installation/plumbing options.
- 10° inline valve angle configuration ideal for everything from naturally aspirated to supercharger, turbo, and nitrous applications.
- Port & Chamber volumes / flow numbers TBD.
- Standard versions designed to work with GM LS7 rockers and equivalent. Doweled rocker stands included with head purchase.
- Solid, stainless 2.180” Intake / 1.615” Exhaust valves standard – interlocking valve seats (like those found in racing heads) standard.
- Accommodates up to 3/8” straight pushrods. See Rocker section for information on solid roller applications.
- 4.065” minimum bore size (can be run on slightly smaller bores with proper head gasket).
- Includes FED Titanium 0.660” lift Spring Kit.
- 285cc equivalent.
- 319 aluminum alloy cast valve covers – same alloy used in most aftermarket and stock cylinder head castings.
- Baffled vent section – Compatible with stock PCV/emissions components.
- -16AN ORB Oil Fill cap included.
- Available with built in coil mounts or without coil mounts.
- Available in two powder coated finishes. As-Cast (no finish) versions available upon request.
Solid Roller Options:
- All F-Series Solid Roller cylinder heads available with shaft-mount, roller tip rockers.
- Available for on-center lifters.
- Solid roller heads will accommodate up to a ½” pushrod.
- F-Series shaft-mount rockers will be available as standard catalog item.
General Recommendations for Frankenstein Cylinder Heads:
- High Volume/Pressure Oil Pumps– We recommend restricting the oil to the top end of the engine when using high volume/high pressure oil pumps. This will help prevent the valve seal from being submerged in oil and will help prevent smoking.
- Pushrods – Please make sure to properly check pushrod length and wall clearance. We recommend a clearance of at least .030” between the pushrod and the wall. Please do not clearance the pushrod holes any further. We have a minimum port thickness required to pass QC and that is set at our facility. Every lifter brand and style use a different pushrod length, so make sure to understand how to properly check the length needed for your application. We also recommend a minimum pushrod diameter of 3/8” with a wall thickness of (.120”).
- Surfacing– Flat or angle milling will affect flow numbers and might require a thicker intake gasket.
- Boosted/Nitrous Applications– With any power adder applications comes increased stress and longevity issues for the valvetrain. We highly suggest the use of Inconel exhaust valves in any power adder combos. We also suggest our upgraded valve spring kits to help properly control the valve train in these stressful conditions.
- All MARINE Applications– We strongly recommend Inconel exhaust valves & also offer a hard-anodized coating to slow the effects of corrosion. Please see note on guide clearance below.
- Valve Guide Clearance – Your FED Heads come with proper guide clearance (.0014″-.0016″) for most applications. Boosted/Nitrous or marine applications might require additional clearance and it is the customer’s responsibility to verify proper clearance in these applications.
- Valve Springs– Forced induction, nitrous oxide and cams with aggressive ramp rates may require additional spring pressure. We offer upgraded valve springs for these types of applications. FED also recommends the use of billet 8620 cam cores and short travel Johnson Hydraulic Roller lifters which tolerate higher spring loads. VALVE SPRINGS MAY NOT BE COMPATIBLE WITH YOUR CAMSHAFT COMBINATION. PLEASE CHECK BEFORE ENGINE ASSEMBLY. IMPROPER SPRING AND CAMSHAFT COMBO CAN CAUSE SEVERE DAMAGE.
- Titanium Valves– “Our Titanium Valves” are coated with CRN and cannot be reground. This coating helps with rigidity and heat protection. If the valves are reground it will remove this protective coating and possibly hurt the integrity of the valve thus increasing the chance for a valve failure. These valves also require a hardened lash cap to be installed on the tip of the valve. These valves are made from Ti-17 and are the best quality available in the industry.
- Stainless/Inconel Valves – The F-Series steel valves are all coated with Black Nitride coating. The Nitride coating vastly increases the hardness of the metal that is treated without changing the material dimensionally like the buildup of a hard coat. This coating not only increases the strength of the valve but increases the longevity of the valve. This is not a spray on coating. This is a surface hardening process and is used a lot in aerospace and military components. We strive to only use the best!
- Piston to Valve– FED assumes no responsibility for damage if the end user builds an engine without properly verifying, he has enough piston to valve clearance (depth and radial clearance both checked). We recommend a minimum depth of .080″ on the intake valve and .100″ on the exhaust with a radial clearance of .030″ minimum around the perimeter of each valve. Just checking depth is not enough, the position of the valve pocket must also be addressed. It is the customers responsibility to verify proper piston to valve clearance.
- CNC Porting– Occasionally a 100% CNC ported head might have a very small area left “as cast”, this in no way affects performance.
- Valve Spring Installed Heights– FED valve spring installed height spec is +/- .015” which is the smallest shim available for adjustment. This small of a difference will have no issues and should be of no concern.
- Stock GM Rocker Arms– GM Rocker Arms are not designed/engineered to endure aggressive aftermarket cams or higher spring pressures/rates. At a minimum FED recommends using CHE Bushing Trunnion Kits. We offer Other available options such as Jesel aluminum and steel shaft mount rockers, along with Crower steel shaft mount rockers. Without the proper parts you will experience accelerated guide wear over an extended period. If you are using GM stock rockers you must use ARP# 234-7207 or GM# 12560961 rocker bolts.
- Jesel/Crower/T&D Shaft Mount Rockers– these rockers must be used for any solid roller application or a high rpm, high cylinder pressure application.
- O-Rings –These O-rings will wear out over time. Removal of the valve covers, headers, and intake manifold, for example, may cause these O-rings to wear faster. We highly recommend a thorough inspection of any O-rings during removal and prior to installation. Worn or damaged O-rings should be replaced.
- Cylinder Head and Valve Cover Heights- Be aware that the F-series heads are ½” taller from the Deck surface to the top of the valve cover rail compared to Stock castings. This may or may not cause clearance issues in some engine bays. The valve covers that must be used on these castings are also taller than stock by ½”, so once again this may or may not create small clearance issues in certain engine bays. When using Corvette (Y-Body) front accessories, additional clearance may be required for the alternator. Please make sure to verify clearance before purchase. It is your responsibility to verify the fitment of our product to your specific vehicle, build, and application, including any modifications. Fitment issues discovered after purchase are not valid for return or refund of the product.
- Head Stud Sizes- The F-series heads come standard with clearance for 7/16” studs or smaller for the center 10 bolts and the outer tabs and the deck studs are machined for 8mm standard. ½” and 3/8” stud machining is available upon special order with a lead time of 2 weeks extra. Standard ARP head stud number is 234-4317 for non-oversized studs. Studs also may vary depending on the engine block used.
- Headers – All F-series heads will require LS7 header flanges. These flanges can be used for any vehicle make and model if you specify LS7 flange. These headers also need to have a ROUND flange shape and ROUND header tubing coming off the exhaust ports. It may be possible to modify your non-LS7 header flange to fit. If you use a non LS7 header flange without modification, the exhaust port will be covered partially and could cause power loss. To help clarify and provide an example, if you were purchasing a set of Kooks headers for a 2001 Trans AM, you would need to request an LS7 flange.
- Head Gaskets – All F-series heads use a minimum bore gasket of 4.125”. We recommend Cometic as the choice in head gaskets unless your power levels exceed 1300hp. At power levels of 1300-1800hp we recommend Athena 6-bolt gaskets with stainless wire. For any power levels over 1800hp we recommend having stainless hoops installed into the cylinder head castings and then having the engine block cut for receiver grooves to match the heads. This process requires the use of a Cometic or other copper gasket.
- Oil Dipstick Mounting – The F-Series does not have the factory oil dipstick mounting holes machined in the casting. We decided that we needed to provide better cooling throughout the head, and we added additional water passages along the upper exhaust flange of the casting. We recommend using one of the header bolts to properly secure the oil dip stick.
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