Lockwood Engineering LLC
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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 variations in compression ratios and carbon build up, Ing. timing Early Alum heads can grow as much or more as .025" and will have more mechanical noise when using a Hydraulic Grind cams instead of cams designed for a Solid lifter.
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" some @.004"
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
well maybe.
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
Intake
Exhaust
Overlap LSA
SRC-468S
Cam made from orginal Tom Sifton design data.
High ramped
Camshaft timing information measured @ .053
OPEN CLOSE DURATION
Intake 33 53 266
Exhaust 53 33 266
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
Intake 30 60 270
Exhaust 60 30 270
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
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