Secrets Magazine INDEX

Roof 101 Specifications

Updated 8/10/2021
Need more info? Have a Question? Please call  or email me:  
Charlie Yapp,  513-724-0700, [email protected]
Reproduction of Robert Roof’s 1929 R&R Cyclone OHV.
Co-Designed by “Chief Engineer” Jim Roof and produced by Charlie Yapp
Four Port “F” (type) OHV Performance Cylinder Head Fits Ford 1928-1934 Four Cylinder Engines.

Cylinder Head:   Nickeled cast iron, heat treated for stress relief. 

Color:    Iron is baked black enamel. Can be recoated.

Combustion Chamber:   140 cc (+-) approximately 7:1 CR @ stock bore, with gasket and no pop-up.

Rocker Boxes:   356-T6 cast aluminum, fine grain surface. Not polished or coated.

Rocker Box Cover:    Manganese bronze fine plaster mold castings. Not polished.

Gaskets:    1 cylinder head, 1 water pump, 4 npt plugs, 1 fire wires, 10 Rocker Box to Head sealing O-rings.

Machine work:    CNC machined to four decimal points, including combustion chamber.

Oiling:    Pressurize to rockers. Idle 4 psi hot minimum. Model A’s meet this spec..

Valve Train 
Rockers:    Roller rockers, ratio 1.5:1,  7/16” stud. Valves seat to cast iron portion.

Rocker Ball:   SBC with Polylock and jam nut, 7/16 stud.

Rocker Stud:  7/16-20 thread, extra long, drilled for oil, hardened & custom made.

Valves:   4 Intake S.S. Valves-In-Head, “F” type 1.73” diameter, stem 11/32” X 5-1/2” L.

Guides:    Cast iron one pc, .595” OD  X 2.610” L, with umbrella seal.

Spring:    SBC, 1.220 OD  X 2.085” free height.  Spring psi at 0.500” lift = 84#.

Spring Seat:   Washer, hardened, 1/8” steel.

Retainers:  SBC, 1.97” OD X .386 ID

Lockers:   SBC, 7 degree, 2 pc.

Push Rod:   Steel, solid, hardened, 11-3/8” L, Custom made.

PR Guide:   Steel hardened custom 

PR Seat Bolt:  3/8-24 hardened allen head cap screw, 1-1/4” L , screws into your tappets.

Distributor Drive-shaft:   Sized to fit head with ignition in low position. High position is optional.

Distributor:    Not Supplied - Use 1928-1934 stock or aftermarket ignitions (CCW)

Water Pump:    Not Supplied - Use 1932 Ford B pump (late ‘33-’34 pumps are short).

Spark Plugs:  Not supplied - 14mm, 3/4” reach, flat seat with gasket: AC Delco R44-XLS or Autolite 64. 

Distributor Riser:   Raises distributor 2” to enable use of Winged cap and or manual spark advance, longer drive-shaft included.

Intake Manifold:    Optional - custom 4-port - 3 carburetor, downdraft; has hot water chamber; comes with 2   block off plates, 7 gaskets, 2 plugs and cast aluminum name badge.

Carburetor Adapter:    Optional - adapts Ford 2 bolt to Ford 3 bolt - Dual Stromberg 97 carbs recommended.

Side Valve Cover Plates:    Optional -  Model A and B sizes with oil bosses and name plate, aluminum smooth castings.

Camshaft*:    Optional - Our Dual pattern brand new camshaft is perfect for highway speed.

Assembly:  Head is delivered assembled. The valve train and rocker boxes can be removed for painting,   polishing, etc. and reassembled without alignment issues. Special tools, normally available locally, are required to remove valves and rocker stud.

Your Block:   Your rebuilt engine should have a metal timing gear, adjustable “single locker” tappets. Valve Plugs (supplied) must be fit to the unused intake valve seats.

*The Roof 101 Cyclone has a 1.5:1 rocker ratio. This runs great with a Model B type grind.
 A Dual Patterned cam grind (road, track, full-race)  lowers the Intake lift. Intake is then increased by 1.5 to create maximum power.
The 0.303” lift Model B cam will be 0.455” lift. 
A 0.356” lift cam (3/4 race) will be 0.534” lift. This could be too high for best performance & durability. The practical limit of this head, without additional machine work for valve to piston clearance is 0.600” lift.