14. Fresh set of 5⁄16-inch stem diameter black nitride valves in front of a different set of stock valves.
John squeezed in a 1.94-inch intake into the combustion chamber, compared to the 1.85-inch stock valve. They were able to design in a larger valve with more functioning space around it. The crest in each port allows for more valve guide support but still enhances the port flow.
15. The smaller and lighter titanium collar (left) reduces weight for better valve contro
John replaced the stock cast iron valve guides with bronze magnesium components. “I like these work-hardened valves and guides, because I can run a much tighter valve stem-to-guide tolerance,” John said. The tighter tolerance affords heat dissipation from the valve through the guide. The enhanced grain structure in the guides acts as a heat sync pulling blistering temps off the valves. All these elements make for a longer-lasting valve train. These amazing aerodynamic guides come with Viton seals built into the structure of the guides. They also run a thicker, more robust exhaust guide for additional heat dissipation.
For Evo heads, the Branch team installs one-piece stainless valves with chromed stems and stellite tops where the valve meets the rocker for additional hardened strength. For Twin Cams and baggers, John recommends black nitride valves with a Teflon coating.
“I use the stainless valves in Evos because the guys don’t lug them,” John said. Branch-O’Keefe valve seats are nickel chromium and capable of running valves up to 2 inches in diameter. The biggest valve you can put on a stock seat is 1.90. The Branch-O’Keefe seats are machined with an interference fit of 0.007-inch so they will never rattle in the heads or ever fall out. Factory seats are only 0.0025-0.003 larger than the hole in the head. He heats the heads to 300 degrees and freezes the seats before assembly. The nickel chromium seat material will take any unleaded fuel and won’t pit.
16. On top of the keeper and spring is a precision-machined titanium keeper on double wou
Each valve seat is cut at 45-60-30 degrees, three angles. With porting, it is the equivalent to a 5-6-angle valve job. Each valve is ground to 45 degrees, and John uses a special carbide-honing bit to ream the guides. It is designed with a reverse spiral so it runs clockwise and it is set to slip fully into the guide before it begins cutting, for an absolute straight ream. Each bit costs more than $200.
John and the Branch team hand-lap each head. “We can modify heads for any performance application,” John said. “It is no longer a one-size-fits-all world.”
The master in the clean room is Paul, a former Honda race tuner. “He’s great at tech support,” John said, and I could tell Paul wanted to talk to the milling machine more than me. “We like to find out what a guy rides, and how he rides,” Paul said. “It helps to find out what they have in their engine, what kind of intake, and carb.” Sometimes, the intakes are polished and Paul can make carb configuration and tuning recommendations. Even Branch-O’Keefe valve springs are top of the line. “We have a five-year track record of no failures or pressure drop,” John said. “Some springs drop 20-30 pounds of pressure in a race bike after just 50 dyno pulls.” The springs are shotpeened, stress-relieved, and then tested at 180 pounds on the seat. The springs are capable of 0.675 cam lift. John uses only chromoly collars and retainers.
17. Accounting for tolerances the new valve setup will safely allow up to 0.685 lift cams
If the esteemed editor will afford us the opportunity, we may bring you another tech on the completion on this motor with Crane roller rockers, manufactured by S&S, Feuling cams, lifters, easy-to-adjust pushrods, and a brand-new Yankee Engineuity EFI throttle body that is sure to rock the fuel injected world. Of course I want to share that big news with the Baggers’ audience. Besides, I still owe you one after you bailed me out following that, um, “misunderstanding” with the South American Federales. –Ed. B
18. This is the beautiful end product of the Branch-O’Keefe head work. But, that’s just the beginning. Come back and see just how well the rebuilt Twin Cam engine performs.
Popular Branch- O’Keefe Head Configurations:
#4 Heads for Twin Cams and Evos
This performance head is designed to fit a variety of engine configurations and riding styles. #4 heads work applications of varying displacements with compression ratios of 9.6:1 for the Twin Cam and 8.9:1 for the Evo. This results in a head that performs much higher than its stock counterpart.
PT Heads for Twin Cams
The PT cylinder head is specifically designed for touring riders with 88-95ci Twin Cam engines. This design provides low-end torque that is often required for heavily loaded, long-distance motorcycles. Compression ratio is approximately 9.5:1 when used with Branch-O’Keefe flat top pistons. The result is power where it’s most needed: in the 2,000-4,000-rpm range.