-PRE-1973 Historic Formula Ford Regulations-

I.      DEFINITION

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A class for single seat, open wheel race cars raced before 1973 by private owners, using the standard Ford 1600 crossflow, pushrod engine. The following commercially constructed cars are eligible.

	Alexis	14 (1968) 15 (1969) 18 (1970) 18B (1971) 22 (1972)
	Beach	MKII (1969-70)
	Bobsy	(1969)
	Caldwell	D9 (1969) D9B (1970-71)
	Crossle	16F (1968-69) 20F (1971-72)
	Dulon	LD4 (1967) LD4B (1968) LD4C (1969) LD9 (1970-72)
	Elden	PH6 (1969) PH8 (1970-72) PH10 (1972)
	Elfin	600 (1969-72)
	Forsgrini	MK12 (1968-69)
	Ginetta	G-18 (1969)
	Hawke	DL2 (1969) DL2A (1970) DL2B (1971) DL9 (1972) DL9A (1972)
	Le Grand	MK10 (1969-72)
	Lola	T200 (1970) T202 (1971) T204 (1972)
	Lotus	31 (1967) 51 (1967) 51 B (1968) 51 C (1969) 61 M (1970-72) 61 MX (1972) 69 (1971-72)
	Macon	MR7B (1969) MR8 (1969-70) MR8B (1971)
	March	709 (1970) 719 (1971) 729 (1972)
	McNamara	FFA (1970)
	Merlyn	MK11 (1968) MK11A (1969) MK17 (1970) MK17A (1971) MK20 (1971) MK20A (1972)
	Mirage	MK5 (1970)
	Mistrale	(1969-70)
	Nike	MK4 (1968-69) MK6 (1970) MK10 (1971-72)
	Royale	RP2 (1969) RP3 (1970) RP3A (1971-72) RP16 (1972)
	Tecno	FF (1970)
	Titan	MK4 (1969) MK5 (1969) MK6 (1970) MK6A (1971-72) MK6B (1972)
	Winkleman	WDF1 (1969) WDF2 (1970) WDF3 (1971) WDF4 (1972)

Any otherwise eligible Formula Ford, not on the MR Eligibility List, may be considered for eligibility upon application to the MR Board by the car owner.

II.     ENGINE

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	a.	General The engine shall be the standard Ford 1600 pushrod crossflow, as installed in the following vehicles: Original version: Cortina 1600 GT, through 1970 model. Uprated version: Cortina GT 1600 (1971), Capri 1600 (1971), Pinto (1971). Components shall not be interchanged from the original and uprated versions of the engine. Regulations pertain to both versions unless otherwise stated. The engine shail not be altered, modified or changed in any respect, unless specifically stated herein. Balancing of all moving parts of the engine is permitted provided that such balancing does not remove more material than is necessary to achieve such balance. Maximum compression ratio: Original engine: 10.0 to 1 Uprated engine: 9.3 to 1 Minimum unswept volume per cylinder: Original engine with std. pistons: 44.4 cc. Original engine with +.030" pistons: 45.1 cc. Uprated engine with std. pistons: 48.2 cc.
	b.	Block Bore may be enlarged to increase clearance between piston and cylinder. Cylinder liners may be fitted. The top surface of the block may be milled to obtain the maximum compression ratio, as specified above. Any steel centre main bearing cap is permitted.	TOP
	c.	Cylinder Head Ports may be reshaped by the removal of metal as long as the port diameter at the manifold face of the head does not exceed the following: Inlet: 1.42" Exhaust: 1 . 16" Combustion chamber (original engine only): Min. depth: 0.12" +/- .005" Max. length: 3.15" Minimum volume per cylinder: 7.8cc. Reshaping is prohibited. A standard dimension head gasket shall be used. Head gaskets may be exchanged between the original and uprated engines. (See permitting modifications, S(ii).)
	d.	Inlet Manifold The ports may be reshaped by the removal of metal as long as the following dimensions are maintained. Original Engine         Uprated Engine Max. size at head face: cyl. 1 & 4         1.48 X 1.28" 1 .24" cyl. 2 & 3 1 .25" 1 .25"   Max. size at carb flange: 3.060 X 1.389" Max. Iength: 3.80"   Primary choke end radius: .709" Secondary choke end radius: .787" The carb face of the inlet manifold may be machined to the horizontal to compensate for the fore/aft tilt of the engine. Water passages in the inlet manifold may be plugged.	TOP
	e.	Pistons Standard .015" oversize or .030" oversize may be used in the original engine. Only standard size pistons may be used in the uprated engine. Original Engine Uprated Engine Maximum dia: standard 3.189" 3.189" .015" OS 3.204" Not Permitted .030" OS 3.219" Not Permitted   Depth of bowl (+/- .005") 0.500" 0.500" Max. dia of bowl: 2.28" 2.28" Min. vol. of bowl: 31.50cc 31.50cc Centreline of wrist pin to crown:     1.737" (+/- .002") 1.737" (+/- .002") Overall height 3.30" 3.30" Min. Weight with rings and pin 573 grams 555 grams Weight of pin 115 grams (+/- 2 grams) 115 grams (+/- 2 grams) Piston make is free provided: (i) one oil control and two compression rings are used (ii) no modification is made to the piston for the installation of rings.	TOP
	f.	Valves Original Engine             Uprated Engine Distance apart at centres:             1.540" (+/- .020") 1.540" (+/- .020") Max. dia. Inlet: 1.502" (+/-.020") 1.560" (+/- .020") Exhaust: 1.252" (+/- .020") 1.340" (+/- .020")   Overall length: Inlet: 4.280" (+/- .006) 4.367" (+/-.020") Exhaust: 4.260" (+/- .006) 4.355" (+/- .020 ) Reshaping of the valve is specifically prohibited.	TOP
	g.	Camshaft The camshaft lobe profile shall not be altered. The following specs are provided for checking only. Lobes, heel to toe: Inlet: 1.311" max. Exhaust:       1.312" max. Lobes, base circle radius: Inlet: 0.540" Exhaust: 0.545" Lift at top of pushrod: Inlet: 0.231" (+/- .002" max.) Exhaust: 0.232" (+/- .002" max.) Lift at spring cap with zero tappet setting:       Inlet: 0.356" max. Exhaust: 0.358" max.
	h.	Valve Springs Valve springs and valve spring shims are free except that: (i) No more than one spring per valve (ii)       The standard spring cap and retainer must be used.	TOP
	i.	Pushrods Minimum stem dia.:       0.25" Overall length: 7.64" (nominal) Minimum weight: 50 grams
	j.	Connecting Rods Minimum weight: both engines 640 grams Note that weight includes cap, bolts and small end bush, but not the bearing shells.	TOP
	k.	Crankshaft Weight:       Original engine:       23 Ibs. 8 oz. minimum Uprated engine: 24 Ibs. 8 oz. minimum Stroke at piston: 3.056" (+/- .004)
	l.	Flywheel Weight with ring gear and dowels:       Original engine:       18.00 Ibs. (min.) Uprated engine: 20.00 Ibs. (min.)
	m.	Carburetor Weber: 32DFM, 32DFD or 32/36DGV Venturi diameter: Primary—26mm, Secondary—27 mm. Permitted modifications: (i) The fitting of any jets (including accelerator pump discharge nozzle) which may be fitted without modification to the carb body. (ii) Modification or substitution of the external throttle linkage. (iii)       The fitting of internal and/or external anti-surge pipes. (iv) The fitting of a velocity stack. (v) The fitting of any filtration device, directly to the carburetor. No scoops, snorkles or ram air devices, unless original. (vi) Removal of the choke butterflies and linkage.	TOP
	n.	Fuel Pump: Free	TOP
	o.	Exhaust Manifold: Free
	p.	Oil pump and sump: Free; dry sump system is permitted.
	q.	Cooling system: Radiator, fan, pump and generator belt: Free
	r.	Electrical System Distributor: Standard Autolite, Lucas, or Bosch with single points only. The vacuum advance mechanism may be removed. Transistorized/electronic ignition is prohibited. *Mechanically operated breaker points are to be the only means allowed to trigger the ignition. The use of more than one set of points is not permitted.
	s.	Miscellaneous (i) The timing chain/sprocket cover may be altered or replaced. (ii) The use of the following non-standard replacement parts is permitted, provided their use does not result in any unauthorized modification to any other component. —fasteners (nuts, bolts, screws, studs, etc.) —gaskets made by manufacturers other than Ford may be used providing the headgasket, carb to inlet manifold, and inlet manifold to head are of identical dimensions to the Ford standard part. —washers —seals —connecting rod, crankshaft and camshaft bearings of the same size and type as original. Normal over/under size bearings are permitted. (iii)       Mechanical tach drive is permitted. (iv) The crankcase breather may be altered or removed. (v) The rocker cover may be altered to provide for Crankcase ventilation, the filler cap may be altered or replaced. (vi) The crankshaft and main bearing caps may be treated with salt bath nitriding covered under SAE specification AMS 2755A (tufftriding etc.).	TOP

III.	TRANSMISSION	TOP
	Any transmission may be used with not more than four forward speeds and an operational reverse.
IV.	FINAL DRIVE
	Any final drive may be used except:       drive shall be to the rear wheels only. limited slip and locked differentials are prohibited.
V.	CLUTCH
	The use of any single plate clutch is permitted provided no modification is made to the flywheel other than changing the points of attachment of the clutch to the flywheel. Flywheel may be modified to accept a single plate sintered metallic clutch (e.g., AP Borg and Beck, Tilton etc.) providing no other regulations are broken.
VI.	CHASSIS	TOP
	The chassis shall be of tubular steel construction with no stress bearing panels except the undertray and a single transverse bulkhead. The curvature of the undertray shall not exceed one inch. The tubes may transport liquid (oil or water) unless specifically prohibited by current general competition rules in the region. Monocoque construction is prohibited. With the exception of safety related tubing (6" maximum length), no modifications from the original are allowed.
VII.	SUSPENSION AND RUNNING GEAR
	All components shall be of steel with the exception of hub adaptors, rear hub carriers, bearings and bushings. Wheel spacers shall not exceed 1.5". Shock absorbers are free except that they must be steel and not have a remote reservoir. The replacement of "metalastic" and plastic type bushings with the spherical type is not prohibited. They must, however, not result in any extra adjustability, or change the outward appearance of the original component. Sound engineering practices must be observed.
VIII.	BODY	TOP
	No part of the frame or body shall project beyond a plane connecting the vertical centrelines of the front and rear tires. The driver's seat must be capable of being entered without the removal or manipulation of any part or panel. Wings (airfoils) are prohibited.
IX.	BRAKES	TOP
	Free, except the restriction to cast iron calipers and iron discs. *The addition of cockpit adjustable brakes bias systems is prohibited unless it can be proven to be period authentic on any particular historic Formula Ford.
X.	WHEELS
	Wheels shall be 13" pressed steel disc type with a maximum width of 5.5". Wheels must be of standard manufacture, but the offset may be altered.
XI.	TIRES
	In accordance with the wishes of the majority of 1994 Formula Ford drivers interviewed, the following "spec tire" rule has been approved: Monoposto Racing Historic Formula Fords will use only the following: Front:       Dunlop 135/545-13     CR82   9092   Formula Ford Rear: Dunlop 165/580-13 CR82   9092   Formula Ford Standard 9092 compound only (476 not allowed). Additional grooving or hand-cutting is not allowed. Rain tires are not allowed.
XII.	MINIMUM WEIGHT	TOP
	The minimum weight is: 925 Ibs. (including coolant and lubricants, but no driver and fuel). Note that this is approximately 5% above the original rules. The intent is to encourage the use of all safety related items. The use of full height rollbars, with additional fore and aft braces, dash hoops and fire-systems should not be omitted for fear of a weight penalty. *Suspension and Running Gear - The substitution of CV joints for donuts is specifically prohibited. All historic Formula Fords must use donuts in the drive line with the specific exception of the Merlyn Mark 20A.
XIII.	FUEL TANKS
	All fuel tanks must be properly secured. The original elastic cords are in most cases inadequate. Fuel cells are required. They must be of a type approved by CASC, SCCA, FIA, IMSA, NASCAR, etc. for road racing. Tanks must be in the original location or if relocated be entirely within the chassis frame.
XIV.	ORIGINAL SPECIFICATIONS
	All Historic Pre-1973 Formula Fords must compete in the identical specification as manufactured. Updates and modifications, however "period" they might appear, are specifically prohibited. Relocation of suspension pickup points, alteration of wheelbase or track are examples of prohibited modifications. All body panels originally supplied with the model, with the exception of the engine undertray, must be used. They must be the original shape. The car must be restored to the original period specs, unless otherwise approved in writing.