Power is an interesting thing. Whether it's achieved in the societal hierarchy of our capitalistic class structure or in the top end of a Twin Cam, once you've achieved it, you still search for more. It's confidence laced with accomplishment-or so we've been told. We definitely wanted more power. But we were looking for it in a Twin Cam B motor, so we started with the top-end and asked for a helping hand from V-Twin innovators Branch-O'Keefe. Jerry Branch started working on Harley-Davidsons in 1969 and hired his apprentice John O'Keefe-who owns the business today-in 1974. Branch-O'Keefe knows heads like the back of their hand. John could probably port/polish a head with a blindfold on. We took a trip over to Branch-O'Keefe's shop in Signal Hill, CA, for a step-by-step explanation on how to port/polish heads. It's fascinating.
When we finished we headed next door, literally, to Bennett's Performance. Bob and Eric Bennett are very knowledgeable when it comes to motor work: top-end and lower-end. They've been in business since 2000, and we can rely on them to do a thorough job. We gave Eric the Branch-O'Keefe #4 Heads to work his magic on a '07 H-D Street Glide. This bike already had a 2-into-1 Vance & Hines Pro Pipe and a Doherty AirCleaner, which raised the numbers quite a bit from stock. But what really interested us in doing a makeover of this caliber on this bike was the Zipper's Performance Thundermax Closed Loop EFI Autotune system. We wanted to see just how "automatically" the Zipper's EFI system tuned itself after installing the heads, along with the Andrews 54H Cams, and H-D Screamin' Eagle pushrods to compensate for the larger valves. Then it was sealed up nice and tight with a Cometic '02-Up Twin Cam Top End Gasket kit.
That feeling we were looking for was in our grasp. Follow along as we show you how we achieved it and take note on how the Zipper's unit actually tuned itself. HB
1. Here is the entire lineup of components that we installed on the '07 96-inch Twin Cam: Branch-O'Keefe #4 Heads (MSRP: $950.00), Andrews 54H Cams (P/N 216354, MSRP: $273.36), Cometic '02-Up Twin Cam Top End Gasket kit (P/N C9146-030, MSRP: $98.15), and H-D Screamin' Eagle Pushrods (P/N 17997-99A, MSRP: $149.95). The total cost for parts (excluding labor) was $1,471.46. | 
2. Notice the stock head on the left compared to the Branch-O'Keefe head on the right. The Branch head has been fitted with oversize valve seats made from nickel-chrome, and performance valve guides. Then they are ported to accept the larger hard chrome stainless steel valves with stellite tips and a polished face (new intake valve is 1.940 inches, new exhaust valve is 1.610 inches; stock intake valve is 1.840 inches, stock exhaust valve is 1.565 inches). The valves and combustion chamber have a polished surface to help enable more air/fuel flow and increase velocity. | 
3. Here, John removed the stock valve springs, collars, valves, seals, gaskets, and rings, and then wiped down the residual oil/debris from the stock heads. Then he glassbead-blasted the combustion chamber and ports to remove all the carbon build-up, and finally blasted out paint from the ports and combustion chamber (H-D paints their heads and machines afterward). When he finished bead blasting, he blew out the debris with an air hose. |
4. John airhammered out the stock valveguides. Then he placed a dummy valve into the empty valve guide cavity and welded the valve seat so that it shrinks in size and it's easily tapped out with a hammer. | 
5. Once the seats and guides were removed, John heliarc-welded the combustion chamber (pictured here is the welding process partially completed). Reshaping the stock combustion chamber to Branch's "Bathtub" chamber is a key component to the Branch process. Air/fuel flow improves and the smaller 80cc chamber causes higher compression and more power. | 
6. When he completed welding the combustion chamber, he placed the head on a milling machine. John started by cutting off 0.030-inch from the deck (at the end of the milling process the total surface cut from the deck is 0.050-inch). He does this so that if the deck is nicked or damaged in any way between the milling process to final assembly, he still has .020-inch to play with. |
7. Then John milled the valve seat pocket for a .007-inch interference fit. The new, larger valve seats are kept in a freezer in order to shrink to their minimal size. When the heads are ready to be seated, they are placed in the oven so that they can expand to their maximum size, which results in the seat perfectly mating to the valve seat pocket. John's never had a seat fall out. | 
8. The new oversized valve seats and AV&V valve guides were installed and it was off to the porting room to port and polish the heads. Branch-O'Keefe's porting/polishing techniques are based on their extensive research on the flowbench and dyno. | 
9. Here's a look at what goes on in the porting/polishing room. Porting is the shaping of the combustion chamber and ports to increase the amount of air passing through the ports. This doesn't make the port bigger, but it improves the shape for optimal airflow dynamics. Branch's "bathtub" design makes the air flow more completely and thoroughly. John ported with a solid-carbide burr bit on an air gun, and then changed to 80-grit cartridge roll, then to a 120-grit, 180-grit, and finally a 240-grit (John emphasized the importance of the porting prep work for polishing. Polishing could take roughly 30 seconds if the heads have been thoroughly ported). After porting, it was time for polishing. Polishing is important because a stock head's chamber builds up with carbon due to its rough, cast material. With a lot of carbon buildup, detonation is affected and causes a spike in performance. John removed all of the carbon and polished the chamber with a Canton flannel wheel and a jeweler's rouge compound so that no carbon builds up on the ports, therefore increasing airflow. After the port/polish process had been completed, it was time to move onto lapping the valve. |