TIMING REQUIREMENTS (specific to Big Twin and XL models only)
Be sure to disconnect the battery before performing any electrical upgrades. Total timing from the factory is 35 degrees BTDC. "Hemi Performance Engineering" heads require less timing because of their efficiency, therefore, retard timing 3-5 degrees. Total base timing for "Hemi Performance Engineering" heads should be 30-32 degrees. General settings concerning aftermarket ignitions: if your box has a rear cylinder offset, set it to the maximum (negative) offset setting. Set dynamic timing (advance slope) to the minimum setting. Dynamic timing directly relates to the advance curve that is preset in the box. Usually there are 3-5 dynamic curves to choose from. If the ignition has a multi-spark option, keep it disabled. Do not disconnect the VOES. The VOES introduces dynamic timing via manifold vacuum. Manifold vacuum is based on barometric pressure and atmospheric changes. The VOES allows you to ride through different temperatures, humidity, and altitudes without having to adjust timing or fuel. If you disconnect the switch, you may experience difficulties in varying environments. Rev limiter should be set conservatively at least for break-in. We suggest a 5000rpm limit until the break-in criterion is met. We prefer Crane’s HI-4, HI-4E, or Daytona Twin Tec ignition boxes for their unparalleled versatility. We can give you baseline settings or preset the box when ordered.
VOES CALIBRATION (specific to Big Twin and XL models only)
The Vacuum Operated Electronic Switch is usually located on the horn mounting bracket and must be re-calibrated to work with "Hemi Performance Engineering" heads. You may need to remove the bracket to locate it. The VOES has a vacuum line that connects it to the carburetor. Remove the switch from the bracket and the vacuum line from the carb. Connect a vacuum pump to the fitting on the switch. Hold the switch close to your ear and squeeze the vacuum pump slowly. When you hear the switch “click”, stop squeezing and look at the gauge to see how many inches of vacuum it took to open the switch. It should be between 3.5 and 4.5 inches of vacuum. On the back of the switch you will see a rubberized coating over the calibration screw. You need to remove all of the coating to access the calibration screw. Use a toothpick, small blunt punch, or a jeweler's screwdriver to remove the coating. Be careful not to gouge the threads of the switch as it is made of plastic and can be damaged easily. Calibration is a means of turning the screw until the desired reading is accomplished. We want the switch to open at 6 to 8 inches of vacuum. If for some reason you cannot hear the switch click, connect a DVOM to the leads of the switch specified in the owner's manual and follow the instructions. During calibration, it is imperative that you hold your thumb over the portion of the switch that houses the screw. After calibration is complete, fill the cavity with 3M-weatherstripping or RTV silicone. Let the switch cure then reinstall.
ELECTRONIC FUEL INJECTION
You must correct and clear all diagnostic trouble codes from the ECM and the TSSM prior to starting the motor for the first time. Additionally, the map provided with your kit must be loaded before starting the motor.
CARBURETOR SETUP
Dyno tuning is a viable tool in extracting the most power from your "Hemi Performance Engineering Kit's ". This should only be done after the break-in period. Severe engine damage may result if this is done before the break-in period. Most late model CV carbs will sustain almost 100hp. If a CV carb is used, it will need a Dynojet kit (or a suitable replacement) to re-calibrate the fuel and air delivery. For break-in procedures, we want the carb to run fat (more fuel). Fat is good for break-in because the worst that will happen is a poor running motor. If the carb is too lean, there is the potential of melting a piston. I won’t bore you with the damage that occurs after the piston lets go, but I will tell you that it’s neither pretty nor cheap. The main jet should be 190 and the pilot jet should be 45. The manufacturer may suggest different jets, but we’ve found that this is a good safe starting point. Your mixture screw should be 2.5 turns out. Your idle circuit (along with the needle and needle position) plays a major role during idle and off-idle throttle response.
If you plan to use a Mikuni flat slide carb, you do not need a jet kit. General jetting as follows:
CARB PILOT MAIN AIR SCREW
HSR42 22.5-25 160-175 1.75 out
HSR45 17.5-22.5 170-185 1.75 out
HSR48 17.5-22.5 180-205 1.75 out
If you find that dialing in the carb is frustrating you, stop and call. Pay particular attention to the bike at different speeds and different gears. Have this info ready when you call.
PUSHROD SETUP
When installing aftermarket pushrods, please read the instructions thoroughly before attempting to adjust them. Different manufacturers have different installations so a few basic rules pertain to all. Rotate engine until #1 cylinder is at TDC and the lifters are at their lowest position (heel of cam). Install pushrods and turn adjustor until there is no vertical (up and down) movement (zero lash). Turn adjustors to manufacturer's specifications. After both pushrods are adjusted on cylinder #1, wait a minimum of 10 minutes before moving to cylinder #2. You need to wait for the lifters to bleed before rotating the engine. To verify that the lifters have bled, shine a powerful light into the spark plug hole and look into the intake and exhaust ports. If you do not see any light whatsoever, the lifters have bled correctly. Use the same procedure for the other cylinder. When all lifters are bled correctly and verified, rotate engine 8-10 more times slowly. Bring #1 to TDC and rotate pushrod. If you can rotate it with a slight drag, that’s perfect. If there is any vertical movement, or the pushrods do not rotate, they will have to be readjusted.
VALVE TO VALVE AND VALVE TO PISTON CLEARANCES
Generally speaking, all brand name cams are compliant with our heads. Including, but not limited to: Andrews, Redshift, S&S, Crane, and Screaming Eagle’s Performance Street cams. "Hemi Performance Engineering" Twin Cam, Big Twin, and XL kits will accept cam lifts up to .630”. Our heads can be made to accept higher lifts but must be specified prior to ordering. Additional machining is required which is not protocol with our street kits. If you would like to use a cam that has a TDC over .200”, and/or lift above .630”, please call so we may verify if said cam can be used. It is the final responsibility of the installer to verify if a particular cam can be used.
GENERAL CLEARANCES
Cam chest:
Check clearance between lobe and case. Sweep cam through it’s rotation, must have .060” minimum gap.
Check clearance between lobe and tappet block (evo) or tappet housing (twin cam). .060” minimum gap
Big Twin only- torque tappet block with used gasket in position. Bring cam lobe to highest position in-line with lifter. Lift up on the lifter itself to verify a minimum .060” gap. If less than minimum, you must clearance tappet block guide so that the roller of the lifter will lift higher in its bore.
Rocker cover:
Position gasket and lower tray onto cylinder head. You should now see the springs touching the lower tray. Mark the areas that need clearance with a marker or a paint pen. Remove cover and affix to a vice. Be sure to cover the vice jaws as not to scratch or mar the cover. Using a small diameter cutoff wheel and a die-grinder, remove only enough material to maintain a .060” clearance through the spring travel. Caution- make sure that you do not break through the cover, grind a little, then stop and check. If done correctly, you should not even be close to breaking through.
When you feel that you have removed enough material, attach the lower tray with a gasket and four screws finger tight. Gently tap cover with a soft mallet to the left of the motor (looking at it from the carb side). Check clearances. Tap cover to the right and check clearances. Remove and grind more if needed.
If using roller rockers, the underside of the top cover may need additional clearance. Twin Cam covers have a support rib that needs to be removed. Big Twin covers may need a spot face.
Roller rockers:
Big Twin and XL- assemble rocker arms in lower tray with shafts, attach to head with a gasket, and torque to spec. Twin Cam- assemble lower tray with gasket to head and torque to spec. Attach rocker support with arms installed and torque to spec. Hold roller on the tip of the valve and look at the underside of the rocker arm where it meets the upper spring retainer. There must be a minimum .060” clearance between the two. If not, mark the position of the retainer on the side of the rocker arm. Remove the rocker arm and hold in a vice. Gently grind the underside of the arm with the cutoff wheel. You will not have much to remove here so be careful. Reinstall and check clearance.
BEFORE STARTING
The following procedures can be done with the intake (complete) and the exhaust in place, however, some of these checks may be easier prior to these components being installed. If the intake components have been installed, make sure the carb float bowl is empty and the petcock is in the “off” position. Fuel injection- remove the quick disconnect fuel line(s). Plugs should be removed and the wires grounded.
Pour 1/4 quart fresh oil (no synthetic) into tappet blocks. This will assure the oil pump does not cavitate. Pour 2 quarts fresh oil into oil reservoir, we will add the rest later. Turn the ignition on, run/stop switch to run, hit the starter button and hold for no more than 5-8 seconds. Wait 20 seconds then repeat. We want to do this 5 times then stop for 1/2 hour. 3 things happen here:
1. The oil pump primes the motor
2. The lifters pump up
3. The rings begin to seat
This entire procedure needs to be repeated 3 times. It is important that you adhere to the wait time, failure to do so will result in a destroyed starter motor. When this procedure is completed, fill the remainder of the oil reservoir according to the factory service manual for your specific model bike.
Perform a compression test. Install compression tester (available at most auto parts stores) on front cylinder. Make sure to use the correct spark plug adaptor and do not cross thread the plug hole. Activate the starter, watch the gauge, let go of the button when the needle stops climbing. Relieve the pressure within the gauge and repeat to verify the final pressure. Stop and record this number. Perform this same test on the rear cylinder. Compare the two cylinders; there should be no more than a 10% variance between the two. If not, the pushrods need to be readjusted.
This test is beneficial in many ways. It tells us if the cylinders are balanced. When the cylinders are unequal, they work against one another. It is also very hard to tune a motor with unbalanced cylinders. On a fresh motor, this allows us to see if the rings are seating correctly by the needle jumping aggressively on the first stroke of the motor. Slow or sluggish pressure may indicate incorrect positioning or an overlapped oil slinger. Either case should be corrected prior to starting. Same holds true for a used motor. If pressure builds slowly, the ring seal may be failing. This test is most often overlooked but is crucial to the performance of your motor.
Set base timing. Twin Cam owners get a break here. The only concern here is that the ignition box initial timing setting is at it’s lowest (negative) position. EFI- timing is already incorporated into map.
BT and XL as follows:
Front cylinder top dead center on the compression stroke. Verify TDC mark on flywheel is absolute center of the timing window. Verify compression stroke, lifters will be at their lowest position (on heel of cam). Most aftermarket ignitions have a static timing l.e.d. There are different locations for ignitions, within the cam cover or under the seat (some models are located under a side cover, usually the left side of the vehicle). Find the ignition module and locate the timing l.e.d. Turn ignition on and run/stop switch to run. The timing light needs to be triggered first (lights up). This is done by either wiggling the Hall’s sensor (ignition is under seat or side cover) or the ignition itself, both of which are located within the cam cover. Once the timing l.e.d. is lit, gently snug the standoff screws only enough to allow it to be rotated. Rotate the ignition (or Hall’s sensor) clockwise slowly until the timing l.e.d. turns off. If you look at the instructions for the ignition, it will tell you to stop there. This means the ignition is set at 35 degrees of base timing. Because of the efficiency of the "Hemi Performance Engineering Head's ", this is too much base timing. Rotate counter-clockwise until the timing l.e.d. turns back on, this is now 3-5 degrees retarded, and secure the standoffs. HELPFUL TIP: rotate back and forth a few times to get a feel on how far it takes you to move the ignition (or Hall’s sensor) in order to turn the l.e.d. back on. The finer the adjustment you make here, the better your overall horsepower and torque numbers will be.
Once the cylinders are balanced, the base timing is set, check all fluid levels and add if necessary. Verify spark plug gap is correct per factory service manual and install with a dab of anti-seeze. Connect plug wires and verify positive engagement. Re-install quick disconnect fuel lines (EFI) or turn petcock on to carb. You are now ready to fire the motor.
BREAK-IN PROCEDURE
This is not limited to easy riding for awhile; break-in starts the moment the motor fires for the first time. HEAT CYCLE: allows the expansion and contraction of dissimilar metals to wear into tolerance under operating temperature. Aside from the other checks involved, this procedure will be the single-most important step before the motorcycle is driven. Start the motor and allow it to idle above 800rpm (oil pumps do not function well enough under 800rpm). There is absolutely no need to blip the throttle or rev the motor at this time. A fan or blower is a good idea, just needs to blow some air across the motor. Let the motor run until you can no longer place your hand on the rocker cover (pay attention, do not get burned). Turn the motor off and let it cool enough to put your hand back on the cover. It is ok to keep the fan(s) running during this procedure. Heats cycle the motor this way 3-5 times consecutively, then let completely cool to room temperature.
Check accelerator pump function: (carb models only) Start the motor and let it warm to operating temperature. Blip the throttle from idle. The motor should rpm quickly and throttle response should be crisp. If sluggish or slow to respond, turn accelerator pump adjustor screw in half turn increments clockwise. Note the change. Better, continue same direction. Worse, turn counterclockwise. There is a little trial and error on your part to find the best AP setting, every motor is different.
After you have set the accelerator pump, change the oil. The motor has moved around enough through it’s heating cycles to have plenty of metal particles within the oil. You don’t necessarily have to change the filter, but it definitely wouldn’t hurt. To prove that point, take the catch pan and swirl it gently in a circular motion. You’ll see the oil appears to be silver floating to the surface. That’s all the metal from break-in. Make a mental note as to how this looks because we’ll use it for future reference.
Finally, its time to ride. Let the motor warm to operating temperature. Take the bike out and vary your speed (city driving)as much as possible. Ride for no more than 10 minutes, turn the motor off, and let it cool enough to put a hand on the rocker cover. Repeat this procedure 3 more times exactly this way. Now you are cycling the motor with a load. It is imperative that you stay under 3000 rpm. Do not ride 2 up. Do not travel the highways; we do not want the motor at a steady speed until we have reached a minimum of 500mi. Do not lug the motor: meaning do not put in 4th gear and run 30mph. Vary engine speeds as often as possible. The motor will continue to settle over the next 500miles and you will eventually feel the motor loosen up. Oil changes are relatively inexpensive and is really the only way to remove the metal from the motor. Preferably, oil should be changed every 100mi and filter every 200mi for the first 500mi. Every time you drain the oil, swirl the catch pan to see how much metal is still there. You should see the consistency of the metal diminish. This is a perfect indicator as to how the motor is breaking in. *****VERY IMPORTANT***** NEVER use synthetic oil for break in. We suggest using Torco’s V-Series petroleum based motorcycle oil for a minimum of 1000mi. After 1000mi, we prefer the use of Torco’s 20-50 synthetic racing oil. Torco T-4R motorcycle racing oil is a superior blend of synthetic and hydrocracked petroleum based stocks designed for high performance motorcycle applications. This MPZ formula features excellent ring seal, anti-foam, wear protection and deposit control under the most extreme temperature conditions.
SUGGESTIONS
Once the ignition timing is set, there is no reason to change it. Carb and exhaust changes have little effect on timing. However, further cam changes may dictate changing timing requirements. Please note that exhaust system changes affect carb jetting. We have seen many examples where drag pipes, or pipes with baffles removed, necessitated a reduction in the main jet size when using our heads. An open pipe will make more peak power, but drastically reduces low and midrange power. Only serious racing engines with high compression ratios will benefit from an open exhaust. There are plenty of exhausts on the market to choose from that will be both esthetically pleasing and kind to your motor. A 2 into 1 pipe or a 2 into 2 with baffles will outperform straight pipes any day of the week. Screaming Eagle low restriction mufflers, Thunderheaders, and White Brothers E-Series work very well.
ADDITIONAL NOTES FOR HIGH PERFORMANCE ORIENTED DEALERS
With a stock bore, stock stroke 80” Big Twin, we have made 86hp on a mild mannered engine up to 101hp on the same engine just by changing the exhaust, carb, and raising compression to 10.5:1. We see, on average, 1.2 to 1.3 horsepower per cubic inch. "Hemi Performance Engineering" heads are so versatile; Evolution OEM castings will fit any bore up to 3.812” with any stroke. Twin Cam OEM castings can allow up to 4 1/8” bore with any stroke. Aftermarket heads will allow larger bore sizes for both EVO and Twin Cam and we can offer almost any compression ratio up to 17:1.
As of this writing, it is still the fastest gas powered, factory cylinder-headed (single plug) bike to ever go down the quarter mile in 8.77 seconds at 147.75mph. Please consider "Hemi Performance Engineering" when building any engine. It is our firm belief that we can provide you with whatever your needs may be with (what is our opinion) the best cylinder heads money can buy.
FOR THOSE WHO KNOW
We mentioned TDC lift earlier. It’s not just a question of TDC lift, but the difference between the TDC lift of the intake versus the TDC lift of the exhaust. Let’s compare a Redshift cam and an Andrews cam. The Redshift has a total lift of .653”. It’s intake TDC lift is .297” and the exhaust TDC lift is .197”. There is a .100” difference between the intake and exhaust. This means that the exhaust valve is already passed (closing) the TDC line of the intake (opening). Additionally, this particular cam requires less valve separation than the Andrews cam. The Andrews cam actually has less TDC lift than the Redshift, but requires more valve separation because there is only .022” difference between the intake and exhaust TDC lift. In any case, it is mandatory to check both clearances when installing high lift and/or high TDC lift cams. If there is any doubt, please call "Hemi Performance Engineering". We can either tell you what will fit, or give you detailed instructions to check it yourself.