Twin-cam fact sheet

Mon, 2 Jun 2008 20:51:28 -0700

This is an overview on the Harley Davidson Twin-Cam engine. This engine came out in 1999. The first engines were known as the ALPA or A engine. In 2000 the BETA or B engine was introduced. This engine is used in the Soft-Tail models and has a balancer to help eliminate vibration. The 1999 and some 2000 engines had defective cam bearing and there was limited factory recall.

CYLINDER HEADS

The casting of the cylinder heads stayed the same from 1999- 2004
The intake valve diameter is 1.840
The exhaust valve diameter is 1.570
Stem diameter is .312
EVO valve spring Pac
EVO guide seals
EVO valve guides

These castings had a small exhaust port

2005 cylinder heads castings

The major difference on these heads
7mm valve guide stems
7mm valve guides - note EVO guides fit these heads
Updated valve guide seal - note updated
Bee- Hive valve springs
The intake and exhaust valve same diameter

These casting will fit 1999-2004 engine and casting have small exhaust port.

2006 cylinder head casting

The major changes on these heads
These heads have symmetrical intake ports
The exhaust ports are large
The intake ports have a raised floor
Valve, guides and seals are the same as 05
These heads need different intake flanges to mount on earlier engines

CYLINDERS

The cylinders over the years have stayed the same. In 02 the casting numbers changed.

These cylinders can be bored out to a 95 kit. Note the only difference from a factory 95 big bore kit is the bore diameter. Everything else is the same.

PISTON KITS

The stock piston is a cast piston that is fitted at .0007 clearance. These pistons are Teflon coated.

Screaming-Eagle offer many piston combination on big bore kits from cast- forge and various compression ratios.

Note determine cam choice/ to match compression ratio. On our home page we a compression calculator to assist in piston and cam choice

CAM CHEST

All Harley Davidson Twin-Cam engines come from the factory chain driven. In 06 on the DYNA model only, they changed the cam chain set up. They went to different chain set up and a hydraulic cam chain tensioner. In 07 all of the Harley Davidson Twin-Cam engine converted to this set up. Note this new set up can be installed in 99-06 engines.

1999 Cam chest data:
Cam chain are the multi- plate HI-VO chain
Outside rear cam sprocket was keyed to rear camshaft
Rear camshaft had roller bearing
Inner cam bearing were junk
Spring load cam chain tensioners

The factory recall include changing the following:
New camshafts with spline drive on rear cam
New inner cam bearings
New cam plate with needle type rear bearing
New splined rear sprocket
New cam chains
Update lifters or the “B” lifter
Updated cam tensioners
Updated oil pump

2000-2006 Cam chest data
The cam chains kept getting more polished to eliminate tensioner wear
New material was used to eliminate tensioner wear on rubbing blocks
The Beta or “B” engine has oil screen in crankcase and a oil passage for balancer tensioners

2006 DYNA and 2007 Cam chest data:
Single roller cam chain inner and outer

New style cam chain sprockets

Hydraulic cam chain tensioner

New designed oil pump

New designed cam plate

Oil pump data:
1999 oil pumps had no wave washer to separate the supply and scavenge side of pump gear
2000 oil pumps were change and had wave washer
2001 the Beta or “B” pump were introduced and used on both the Alpha “A” and Beta “B” engines

Hydraulic lifters
1999 “A” lifters were used for short time
2000 The “B” lifter was introduced and still used.

Cam chest service tips:

The ten cam cover screws are longer in length, note do not use these screws on cam plate. You can damage lifter bores

On cam plate where dowel pin are, watch your torque pressure when you tighten these screws.

Replace cam chains when you change cam tensioners, we also recommend polishing cam chains, it helps eliminate tensioner wear

Inspect cam plate for wear on oil pump surface and crankshaft bushing wear

Check crankshaft run-out if over .004-.005 you have a twisted crankshaft. Crankshaft needs to be replaced or re-trued.

Always center oil pump to crankshaft, this can be done two ways:

1. Use EVO tappet block alignment pins
2. Rotate engine and torque oil pump to crankshaft as engine is rotated

ENGINE CRANKCASES
1999-2002 all Twin-Cam engine both Alpha “A” and the Beta “B” engines used Timken Bearing on the sprocket side to position crankshaft in crankcases
2003-present Twin-Cam engines use a centrical bearing on both sides to position crankshaft. The torque of sprocket bolt centers crankshaft in engine cases.
2006 DYNA has a redesigned set crankcases
2007 Twin-Cam crankcases both Alpha and Beta are redesigned. They have a non-Timken bearing.

CRANKSHAFTS

ALPHA “A” type

There are two type of Alpha crankshafts

99-02 Timken bearing crankshaft
03-06 non-Timken bearing crankshaft

NOTE: these crankshafts are currently non-rebuildable

You can use either crankshaft in all Alpha- models years

06 Dyna crankshaft
07 Stroker Crankshaft

BETA “B” type

There are two types of Beta crankshafts

00-02 Timken bearing crankshaft

03-06 non-Timken bearing crankshaft

Note: these crankshafts can be used in all 00-06 engine crankcases.

07 Stroker crankshaft

BETA BALANCER ASSEMBLY

00-02 balancer parts were all the same. This balancer set up used roller bearings in support plates

03-06 balancer parts were updated. The sprockets were changed and a centrically bearing were used in support plate.

NOTE: 03-06 balancer assembly can be used in 00-02 engines
copyright 2003 Motorcycle Machine

CNC Harley profile

Sun, 1 Jun 2008 12:41:34 -0700

CYLINDER HEAD BASELINE PROCEDURES

Fri, 30 May 2008 12:16:02 -0700

When we get ready to develop a new cylinder head porting program we use the following steps:

PORT AREA
Measure valve diameter
Measure stem diameter
Length of port
Port volume in cc

We take the above data and insert into a computer program. This will give the area of a port which will help in a mathematical determination of port velocity.

This is determined by air flow in CFM and port area at a given lift to estimate port velocity.

FLOW-BENCH TEST

The cylinder head is installed on a flow bench, and both intake and exhaust ports are flow tested. We check air-flow at .050 lifts and at 28 inches of water.

PORT VELOCITY PROBE TEST

While the cylinder head is on the flow bench we test port velocity at the .300 lift and the .550 lift. On the intake test we use a u-shaped probe and on the exhaust test we use a straight shape probe. We check the port at nine points. We start at the top of port measure top three areas of port, the middle three areas, and the bottom part of port. This information is inputted to the computer and a port velocity map is generated.

COMBUSTION CHAMBER

We measure the chamber volume in cc, this used to determine a correct compression ratio. Chamber volume is important to assisting in determining a cam shaft choice. Chamber volume and the intake closing number on camshaft assists us in this determination.

COMBUSTION CHAMBER SWIRL TEST

A swirl meter is a device that shows the direction of air-flow in the combustion chamber. This meter reads the air flow in rpm and in either a clockwise or counter-clockwise rotation. The idea here to make sure the air flow is directed to the spark plug. The higher rpm the more turbulent mixture in the combustion chamber.

CYLINDER HEAD PORT VOLUME SHEET

Fri, 30 May 2008 12:05:24 -0700

TYPE OF HEAD INTAKE EXHAUST

Stock heads

99-04 79cc 60cc
05
06-07 83cc 76cc

Harley Davidson Performance Heads

SE Head 87cc 70cc
HTTC Head
CNC Ported Head
SE 103 Head 95cc 73cc
SE 110 Head
SE 120 Head 107cc 78cc

SBC PORTED HEADS

SCOTTSMAN 99-05 82cc 70cc
SCOTTSMAN 06-07 84cc 82cc
VORTEC 99-05 82cc 73cc
VORTEC 06-07
SBC SE Head
SBC HTTC Head
SBC 103 Head
SBC 110 Head
SBC 120 Head
copyright 2003 Motorcycle Machine

Tech Info

Twin-cam fact sheet

CNC Harley profile

CYLINDER HEAD BASELINE PROCEDURES

CYLINDER HEAD PORT VOLUME SHEET