TC120 Kits

After reading about each kit, click the appropriate button at left to see all possible options you may want.

For both EFI or Carb Models

The above photo is for visual representation only. Parts may vary slightly for different jobs.

Our 120 motor package uses a set of 4.065" bigger  bore cylinders and will require a 4-5/8” stroke crank using standard length rods along with a set of Head Quarters HVP cylinder heads and cams.
You will need to purchase a crankshaft assembly from a specialist like Dark Horse or your HD dealer.
All years of the Twin Cam motors will require case boring to accept the larger bore cylinders. Instructions are supplied with the cylinders and it is very basic machining for anyone with a milling machine, angle plate. draw bar and boring head.
The forged CP Pistons used in our kits are a Head Quarters exclusive featuring a dish in the tops to accommodate the use of stock heads and permit us to create compression ratios varying from 10.5 to 11:1 depending on needs.
Doug (HQ owner)  uses one of these motors in his own Dyna Superglide. Many of our customers are using this motor in their FLH bagger type touring bikes.
The increased stroke provides a better mechanical advantage through rod leverage and the results are higher torque figures at a lower RPM. Mellow 2,000 RPM cruising is possible with plenty of power on tap for explosive throttle response through the whole mid-range and upper end. 

Power and fuel mileage expectations.    Torque       Horsepower         Mileage
Sport Touring                                           140-150         115-125            45 MPG
Sport                                                         145-155         120-130            45 MPG

HQ-TC-120-ST       Twin Cam 120 Sport Touring 10.5:1 compression ratio

The following is a complete list of parts and labor required to build the Head Quarters Twin Cam 120 Sport Touring performance package.

    Qty  Part #                         Description

                                                 HEAD WORK
    1)  HVP-TC                          Your heads completely reworked, ready to bolt back on.
         HVP-TC-MCR                  (as above with mechanical compression releases installed)
         HVP-TC-ECR                   (machined for HD electronic compression releases. not supplied)
    1)  HQ-HEAD-BOARD    Fin Protector (heads bolted to this for shipping)

                                                CYLINDER WORK
    1) HQ-7100-C                   Bore  (4.060") TC cylinders to 4.065")
    1) HQ-8-76868                  Pistons, forged dished top to match stock chamber
    Unfortunately we can no longer buy cylinders from Harley-Davidson and supply them so we have provided the part numbers so you can purchase them from a dealer yourself. The cylinders come with head and base gaskets.
                    Cylinder set, Black & hilite fins as per stock heads
                   Cylinder set, Silver & hilite fins as per stock heads

                                                RECOMMENDED PARTS
    1) HQ-4055                       Pushrods, adjustable EZ install type
    4) HQ-4225                      Hydraulic lifters, Black Ops type
    1)  17033-99                       James rocker cover gasket and seal set

                                       Cam Choices as per drive type and appropriate year

    1)  HQ-TC-575                      Cam, chain drive 1999-06 models (except 2006 Dyna)
    1)  HQ-TC-575-G             Cam, gear drive 1999-06 models (except 2006 Dyna)
    1)  AP-288901                 Kit, gear drive install
    1)  AP-288908                  Kit, gear drive, 1999-06 (except ‘06 Dyna)
    1) HQ-TC-575-HC          Cam, for all 2007-’09 models including ‘06 Dyna

                                        Additional parts for carburetor equipped models

    1) HQ-7025-A                  Port, intake manifold (sens us your manifold)
    1)  HQ-6100                      Ignition, preprogrammed for 1999-03 models
    1) HQ-6104                        Ignition, preprogrammed for 2004 & later

                                                           Optional Parts (not required)
    1) HQ-32679                      Show off your build with a Head Quarters timing cover
    1)  HQ-4600                       Roller Rockers

If you want this job done you will need to print a work order to send along so we know exactly what you need.
Click the red link below to find a work order for this build and print it off.
HQ-TC-120-ST Work Order

You can price any part or the whole job by viewing or printing off a price sheet found on the red link below.