Camshafts

Lockwood Engineering LLC

Sifton Racing Cams for Street and Strip
EVO and late model Shovelhead
Including Black Widow Grinds
Our Sifton Racing Cams are of "orginal-orgin" and not to be confused with the Sifton Motorcycle Products Inc. company,
See Photo gallery.
Tom Sifton Checked all his mechanical lifter cams for over head valve engines @ .053 due too the long high ramp that he incorporated into his designs for the Aluminum cylinder head that when hot has growth. Thus allowing the valve to be slowly put on the seat with out shock or being noisy.
Due to varations in compression ratios and carbon build up, Ing timing Early Alum heads can grow as much or more
as .032"- .040" and will have more mechanical noise.
NOTE: Loss of low end power will result if you use Hyd lifter on a mechanical lifter cam do to the extra duration of the ramp zone!!
Early Flat Head cams were checked at .010"
This page is under construction-Please call or fill out form.
More on how to hop up Shovelheads coming soon From original factory race dept. notes.
Early Pan Head cam for using two front cyl heads or for F & R Swap
for Turbo and and two carbs. Turbos in the 70's I worked this engine configuration in 1974 - 1976 two years to get it right-never again?
well maybe.

       Even though we have lost some great innovators in the motorcycle industry like my early mentor's whom I new all of my child & adult years James Kibblewhite Passed away back in February 2005 Born June 1st of "1923" I will always remember Jim telling me not to let the first failure bring you down it is the learning curve that we all must go through to be able to be better as our achievements will speak for them self-Jim's oldest son Will runs the business on a daily basis carrying out his fathers success in our home town of Pacifica California- Man like we were living right next to the Pacific Ocean! "surfs up"

   Now Jerry Branch is 88 years young and to think he was developing what would be the 1984 Evo cylinder head for the Motor Company back as far of 1976!!My wife and my self will be visiting John and Jerry some time soon for their next U-tube Video on cylinder head porting-check out their first video.

More on some others we locate our earlier web site info.

How do you pick a cam?
How far should the intake valve be open at 75 degrees ATDC?
When does the intake valve close and stop the Intake flow process-and begin the squeeze well is isn't at .053" thats for sure. So when does it close ?
When the exh port is to big stuff a big tulip valve and add some real estate back into port. Tulip valves where used just for this whether or not it is the intake that is over ported or exh. But play a part in getting Torque.
Can the Int valve cause or be a restriction in the system?
How far should the Exhaust valve be open at bottom dead in relation to intake port flow ? Blow Down!
If you use wilder exh lobe on a exh port that is flowing very well what happens to your BS HP- goes out of control.look at Tq curve.
Exhaust gases will not expand more than 7 degrees
10 degrees ABDC the valve seat does recolonize piston movement So again how far should the exh valve be open at BDC
Does a lazy intake port need more over lap to initiate flow because of low velocity due to larger valve for high lift flow? The more you can see of the back of the Int valve the more power you will see.
If you can't fill the cylinder stuff it with a piston-higher compression.
So your cylinder head flow numbers make a difference It is the relation between intake air flow vs exhaust air flow @ BDC & exhaust valve lift

For more info on Sifton Grinds Please Call 303-814-1709
SRC-7112 Old style Cobra Hydraulic
Camshaft timing information measured @ .053
                 OPEN                CLOSE       TDC          DURATION                VALVE LIFT

Intake 28                        45                         253                              .440"
98.5
Exhaust     53                        25                          258                            .440"
104
Overlap    53           LSA

SRC-7112B - "NEW Supper Cobra" Hydraulic
Much more Torque and throttle response good to 96"
Stock Cylinder heads must be set up for this cam.
Cam drops into S&S Cylinder heads.
Camshaft timing information measured @ .053
                 OPEN                CLOSE        TDC         DURATION                VALVE LIFT

Intake         28                        45                         253                              .508"
98.5
Exhaust     50.5                     22.5                          253                              .508"
104
Overlap      50.5         LSA

SRC-412
Camshaft timing information measured @ .053
                 OPEN                CLOSE      TDC         DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA

SRC-468S
Cam made from orginal Tom Sifton design data.
High ramped
Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake      33                            53                        266                            .466" cold .446" hot

Exhaust   53                           33                         266                            .466' cold .446" hot

Overlap                LSA

SRC-468+ for alt style engines only
Cam made off orginal Tom Sifton design data.
High ramped
Must use Mech. tappet do not use HYD
Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake       30                           60                         270                         .466" cold .446" hot

Exhaust    60                          30                          270                         .466" cold .446" hot

Overlap                 LSA

SRC-105 Alt style engine only
Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake      25                          60                            265                       .470" cold.448"hot

Exhaust 63                           22                            265                      .470" cold .448"hot

Overlap                LSA

SRC-109 Alt. style engine only
Can use Hyd lifter
engine size to 88"
Camshaft timing information measured @ .053
                 OPEN                CLOSE     TDC            DURATION                VALVE LIFT

Intake      32.5                        50           .211                262.5                          .440"w/ hyd
99.25
Exhaust 58.5    30 .200 268.5    .440" w/ hyd other wise with solids .418"
104.25
Overlap   62.5              LSA 101.75

SRC-111-118 Alt style engine only
All out performance only
Camshaft timing information measured @ .053
Cam shaft and cylinder head is design toward more drag strip application
Semi-Bathtub Branch style Chamber 1.650"exh valve with 2.050" int valve both 5/16 stems
Re-Located spark plug hole
Trock 3.8125 bore only    long rods   higher than stock rocker arm ratio 1.6
Super "B" carb bored out 1/16"
intermediate adjustable air bleed as well as adjustable main air bleed w/ a 3rd fuel delivery system

This Cam also works well in Harmon big 130+inch engine with Twin carburetor full Hemi cylinder heads
along with Baisley hi-ratio 1.6 rocker arms for .642" valve lift cold .620" hot
Harmon valve sizes are 2.250 int. 1.940 Exh Thin stem .3125

To figure new valve length or new stem protrusion= as a example
( IF .106" is height for stock cylinder head using FL gauge above 90 degrees @ rocker arm to make a .420 lift geometry + 1/2 of new valve lift increase lets say from .420" to .625"=.205"/2=.102----.102 added to.106"=.208" using FL gauge-most of us made our own protrusion gauges for high lift cams. Use for all cylinder heads with higher than stock valve lift to correct geometry at mid lift.

compression ratio of 11.25:1 to 12:1 stroker
early modified Branch cyl heads special anti reversion.use with stepped exh. pipe
Mech lifter design not for use with Hyd lifter

                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake       37                           52      269                               .574"cold .552" hot
102.5

Exhaust    67       37                           284                              .570"cold .552"hot
106
Overlap 74              LSA     104.25

SRC-117 New design more lift. Use with hyd lifters Shorter ramps
More usable power band for the street than strip to be used with Hyd lifter only !
Camshaft timing information measured @ .053
Full hemi cylinder head with stock valve sizes
9.5:1 to 10:1 compression
86" to 96" engines with compression.

                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake      32                          58                          270                              .505"
103
Exhaust 56                          30                          266                               .505"
103
Overlap 62              LSA    103

SRC-625X ALCOHOL Cam
All out Drag cam for highly modified Shovel head like Dan Baisley cylinder heads.
Big "D" Carb 13:1 compression and higher
Large cubic inch engines
Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake           41    63                                                         .644"cold .630"hot

Exhaust        64    21                                                         .644"cold .630"hot

Overlap                LSA

SRC-660X

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA

SUPER V twin Cam regrinding service for the super V which incorporated
a cam similar to small block Chevy more TQ & HP HYD Lifter design
Engine rebuilding service for this rare engine. Originally did a few engines in1987 using
Bill Miller Aluminum connecting rods, forged TRW piston with compression, rebalanced crank, Hard nickel valve seat and tried reground performance cams
From Chet Herbert & Erson

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake      n/a

Exhaust n/a

Overlap                LSA

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA

Camshaft timing information measured @ .053
                 OPEN                CLOSE                 DURATION                VALVE LIFT

Intake

Exhaust

Overlap                LSA