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Head Modifications for the Discriminating Harley® Enthusiast

Ported Edelbrocks®    I offer a myriad of custom Harley Davidson® cylinder head preparation levels, each with numerous options to meet with your individual requirements. I prepare cylinder heads for Pan Heads®, Shovelheads®, Iron and Evolution Sportsters®, Evolution Big Twins® and, of course, the newest Twin Cam® motor. Packages are available as assembled, ready to "bolt on" items or raw, ported heads ready for the individual builder to set up.

   For most Evolution®/Twin Cam® applications, I prefer Ferrea® valves and manganese bronze or cast iron guides from Head Quarters®. I also recommend highly Head Quarters'® valve spring packages and strongly endorse their cams for many street going Harleys®. Leineweber® and other cams frequently get the nod when the bike is to be used for the dragstrip or similar applications. I will utilize your preferred manufacturer's parts if you so choose.

Ported Shovelheads   Modified cylinder heads are accompanied by flow figures from the flow bench. Special flow set-ups including or excluding the normal intake and exhaust plumbing are available on request, as well as referencing to your choice of test pressure. I utilize FlowPRO® computer software created by Audie Technology® to correct and analyze all flow bench data. It is exceptionally useful for scrutinizing critical flow information in a reduced amount of time and to a very relevant degree. It enables a real world look at the entire lift and flow curve...... not just the peak flow figures that so many companies rely upon for much of their advertising. For example, if you have employed a cam that delivers .520" lift at the intake valve, greatly enhanced flow at .600" lift does you no good at all! Furthermore, frequently the modifications done to achieve good flow at upper valve lifts correspondingly hurt flow at low and mid lifts. This results in a head that looks great on paper at lifts your cam never delivers, but a head that delivers poor velocity, throttle response, fuel economy and airflow at the real conditions your motor is set up for. Most street going applications require moderate increases in flow while retaining as much intake velocity as possible for crisp throttle response and good fuel economy at street typical engine speeds. For high rpm and/or large motors, I also offer an optional intake port modification for all Evolution Big Twins® and Sportsters® utilizing intake valve lifts of .550" or greater that dramatically improves high valve lift flow and velocity without hurting low and mid lift flow figures hardly at all.

Ported Evo FL's    I have a lot of experience with many of the major aftermarket cylinder heads including S&S®, STD®, Edelbrock®, etc.. These heads offer many advantages in rigidity, cooling and excellent airflow potential due to design improvements and port wall thickness. I am currently experimenting with the newest Shovelhead® offerings from S&S® which appear initially to be the best aftermarket alternatives for this model to date! For lots of street going packages, many of these aftermarket heads will deliver the required airflow out of the box and further modification is frequently unnecessary. "Enough" airflow to feed your "beast's" engine size at the intended peak RPM's is all you need! And, on that note, there are many times I do not recommend an inquiring individual to have his heads ported. For example, a good exhaust system coupled with a free flowing air filter, a decent "bolt-in" cam, a higher rev limiting ignition module, perhaps a mild increase in compression and a carefully rejetted carburetor on an 80" Evolution Big Twin® is capable of delivering 70 horsepower or more very handily. That's a very healthy increase over stock output (typically 50 to 53 HP)!! If that's all you desire, that's all you need!! I am always honest about when an individual should consider porting and when not to.

Edelbrock® Chamber   All ported cylinder head packages ready to bolt on receive precision, proven port modifications held to exacting measured dimensions. You will never receive a "shined up" set of stock ports from my company. In fact, intake port finish is 80 grit to decrease fuel "puddling" tendencies while combustion chamber and exhaust port receive a 320 grit finish to decrease surface area (and thus heat absorption) and to minimize carbon accumulation. I am not a fan of mirror polishing and have never seen any significant advantages on the dynamometer or flow bench. I prefer to spend my time and effort insuring dimensional integrity and consistency. Valve guides are modified for valve lift, individually fitted to each head to insure proper interference fit, reamed and finish honed to clearance and are application modified as appropriate to further enhance and streamline airflow. Valve to valve clearancing is performed to guarantee compatibility with your camshaft choice. Seats are cut using insert type equipment with a minimum of five angles/radii as application requires and are hand matched to each port and combustion chamber. Combustion chambers are unshrouded for further airflow improvement and good combustion efficiency. Each chamber is cc'd, equalized and then heads are milled for appropriate compression target. Intake manifold porting and matching to each head is part of the package. Flow testing and probing is performed to insure finished product. I also offer solid copper exhaust gaskets as an option to the OEM mesh units that always "mushroom" out into the port when you bolt up your exhaust system.

Workload    I offer recommendations for valve sizes, seat configuration, compression ratio, cam selection, springs, carburetor, intake manifold, air filtration, exhaust system and head flow requirements based on engine displacement, bike weight, rider usage and riding style. I also offer milling, welding and fabrication and custom exhaust system designing. I do not offer service work, engine assembly or routine overhauls. I invite you to please contact me at your convenience for any inquiries you might have. Colonial Cycle Dragbike

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