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351 Cleveland Engine
Mustangs, Shelby and Cobra Data

351 Cleveland

The 351 Cleveland engine is one of the engines in the 335 FORD series of engines.  Other engines in this series are the 351Cleveland Boss, 351 Cleveland HO, 351 M  and the 400 series.

The C behind the engine denotes the place of manufacture - Cleveland, Ohio.  As opposed to a 351 W where the "W" stands for Windsor, Canada its birthplace.  Now to clarify the "M" located behind some of the 400 series engines.  It does not stand for 'Modified" or "Michigan" as most people think.  It is simply a suffix added to denote a different engine from the Cleveland and Windsor.

Some suffixes found on this engine family stand for performance options such as H.O. stands for High Output and CJ for Cobra jet.  As a matter of fact, these engines were the result of Ford's quest for a bullet proof medium displacement high performance engine for use in the production vehicles.  Alas the timing was poor as the gas prices rose and the fickle public went on to grossly underpowered vehicles that moved at a pace between slow and slower.

The 351 Cleveland engines used  "canted" valves and large intake and huge exhaust valves for maximum breath ability. A canted valve is set in the heads at an angle, not vertically.  Canted valves increase performance by allowing the heads to flow a higher ratio of gas and exhaust in and out of the heads than normal valve design.  As a result, power is increased and fuel efficiency is also increased.  Because of these characteristics, 351 C engines are very well known in both the NASCAR and Pro Stock Drag car circles.  When driven in everyday traffic, they can be fuel efficient operating as an engine would if it in the 300 CID size.

The 335 series engines use a dry manifold configuration. In other words, no coolant flows through the manifold.  At the front of the block, there is an integral timing chain cover, at the top left hand side, coolant enters the block through the thermostat and then part of it goes through the radiator and part of it goes through the water pump. At this point below the thermostat on 351 C engines is a brass diverter valve.  This diverter looks small and unimportant but it is critical.  Made of brass it looks like a brass freeze plug with a hole in it and is driven into a seat below the thermostat.  If you have an engine you are going to hot tank, REMOVE THE DIVERTER VALVE.  Hot tanking will eat the brass and no one makes these that I can find.  Your engine will overheat without this valve. To remove the piece, you can generally pry it up from a small hole located below it.  Or you can sometimes drill a small 1/8 inch hole off to one side and remove it with a slide hammer puller.  Do not destroy this piece.  If you feel lucky go to your Ford dealer and ask for part # D0AZ - 8K517-A.

351 C 4 bbl engines produced through 1971 and all 351 C 2 bbl engines use 2 bolt mains. All HO, Boss, CJ and 1972 - 73 engines use four bolt mains.  However, all blocks are cast to accept 4 bolt mains and if you have a set of 4 bolt main caps, you just need to also have enough money to pay to have a machine shop drill out the block and tap it.

The Boss 351 had some differences from the other engines there are: it was fitted with a dual point vacuum advance distributor, it had a rev limiter that was almost immediately removed by the consumer because they did not want to be limited to the 6,050 - 6,150 RPMs that Ford set the device at. The engine was also the only one to receive solid and adjustable lifters.  In 1971, the engine was fitted with an aluminum intake manifold.  All other 351 engines got a cast iron version.

The 351 4 barrel engine was designed to breath, and breath it did.  The intake ports are so big that the engine does not run efficiently until it gets to at very high RPM. In contrast, the 2 bbl engine had undersized ports and did not breath well at all.  It had low end torque, but petered out at higher RPMs. I you are very lucky, there is an Australian version of the manifold that has intake ports that are not quite as large as the 4 bbl version but bigger than the 2 bbl  version. I have never seen these heads, but have read about them in the past.

 
Year bbl  Cylinders CU IN. HP Torque Compression CC Bore x Stroke
1969 2 8 351 C 250@4600 355@2800 9.5:1   4.00x3.50
1969 4 8 351 C 290@4800 385@3200 10.7:1   4.00x3.50
1970 2 8 351 C 250@4600 355@2600 9.5:1   4.00x3.50
1970 4 8 351 C 300@5400 380@3400 11.4:1   4.00x3.50
1971 2 8 351 C 240@4600 355@2600 9.5:1   4.00x3.50
1971 4 8 351C 285@5400 370@3400 10.7:1   4.00x3.50
1971 Boss 4 8 351 C 330@5800 380@3400 11.0:1   4.00x3.50
1971 CJ 4 8 351 C 280@5800 345@3800 9.0:1   4.00x3.50
1972 2 8 351 C 164@4000 276@2000 8.6:1   4.00x3.50
1972 HO 4 8 351 C 266@5400 301@3600 8.6:1   4.00x3.50
1972 CJ 4 8 351 C 248@5400 290@3800 8.0:1   4.00x3.50
1973 2 8 351 C 164@4000 276@2000 8.6:1   4.00x3.50
1973 HO 4 8 351 C 266@5400 301@3600 8.6:1   4.00x3.50
1973 CJ 4 8 351 C 248@5400 290@3800 8.0:1   4.00x3.50
ENGINE SPECIFICATIONS
    Motorcraft   Delco   Fram
Oil filter      
Gas Filter      
Air Filter      
PCV      
Oil 5 quarts of 10W30 or 10W40
Oil Pressure 3535 - 60 PSI
Valve arrangement  
Mechanical Lifter adjustment - Hot Both the Boss and HO engines get 0.025 on the Intake and Exhaust adjustment
Manifold Vacuum  
Warm Idle Manual Trans  
Warm Idle Auto Trans  
Taxable HP  
Distributor Rotation Clockwise
Firing order 1-3-7-2-6-5-4-8
ENGINE TORQUE SPECIFICATIONS
All torque specifications provided in this table are those recommended by FORD. If you use special bolts, follow the torque specifications provided by the manufacturer. I recommend that you use the 3 step torque technique where you torque down the bolts in three equal steps.  Once you have reached the maximum recommended torque setting, go around one more time. Do not torque in a circular pattern.  Always torque cross to cross.
Head bolts 95-100 Oil pan bolts 12
Head bolts Boss 125 Valve cover bolts  
main cap bolts 95-105 Carburetor mount bolts 10
connecting rod  bolts 40-45 Boss Connecting rod bolts 50
Intake bolts 5/16 25 Oil pump 25
Intake bolts 3/8 30 Engine fan 15
Intake bolts 1/4 6-9 Spark plugs  
Exhaust manifold bolts 12-22 Trans. inspection plate  
Harmonic damper 70-90 Water pump bolts 20
A/C Compressor mounts   Clutch pressure plate 35
Motor mounts to engine 85 Upper timing gear bolt 40
Bellhousing bolts 25 Camshaft thrust plate 12
Trans to bellhousing 25 Rocker arms 20
Flywheel to Crankshaft 75-80 Main cap cross bolts  
       
Crankshaft Bearing Journal Specifications
Main Bearing Journal (inches) Connecting rod Journals
Journal Diameter Oil Clearance Shaft end play Thrust on number Journal Diameter Oil Clearance Side clearance
2.2482 - 2.2490 0.0005- 0.0022 0.004- 0.008 3 2.1232- 2.1240 0.008- 0.0024 0.003- 0.010
Piston Ring Specifications
Comp Ring Width Ring side clearance Ring gap width
Top Bottom Top Bottom Oil ring Top Bottom Oil Ring
0.077- 0.078 0.077- 0.078 0.002- 0.004 0.002- 0.004 Snug ---- ---- 0.015- 0.055
Piston Specifications
Code Red Code Blue 0.003 Oversize Piston to Cyl. Bore clearance Piston Pin Bore Dia.
3.9982- 3.9988 3.9994- 4.0000 4.0006- 4.0012 0.0014- 0.0022 0.9122-0.9125
Valve Specifications
Year Seat angle Face angle Valve spring pressure lbs/inches Valve spring installed height (in) Stem guide clearance (in) Stem Diameter (in)
Intake Exhaust Intake Exhaust
1969 45 44 215 @ 1.34 1 25/32 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
1970 2V 45 44 209 @ 1.42 1 13/16 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
1970 4V 45 44 285 @ 1.31 1 13/16 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
1971 2V 45 44 210 @ 1.42 1 13/16 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
1971 4V 45 44 285 @ 1.31 1 13/16 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
1972 2v 45 44 210 @ 1.42 1 13/16 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
1972 4V 45 44 285 @ 1.31 1 13/16 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
1972 CJ 45 44 315 @ 1.23 1 13/16 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
1973 HO 45 44 282 @ 1.32 1 13/16 0.0010- 0.0027 0.0015- 0.0032 0.3420 0.3415
Camshaft Lift
Engine Year Intake Exhaust
    @ lifter @ valve @ lifter @valve
351 C - 2V 70-74 0.235 0.407 0.235 0.407
351 C - 4V 70 0.247 0.427 0.247 0.427
351 C - 4V 71-72 0.247 0.427 0.247 0.427
351 C - 4V 73-74 0.277 0.480 0.283 0.490
351 Boss 71 0.290 0.477 0.290 0.477
351 HO 72 0.298 0.491 0.298 0.491
351 CJ 71 0.277 0.480 0.277 0.488
Year Spark Plug Plug Gap Dwell Point Gap Intake Exhaust Carburetor
1969 Autolite ARF-42 .032"-.036"   2.185"- 2.195" 1.7045"- 1.7145" Autolite 4300 (4V)
Automatic choke
1970 2V Autolite ARF-42 .032"-.036" 24-29 (manual)
26-31 (automatic)		 .017" 1.9025"- 1.9175" 1.533"- 1.548" Autolite 2300- (2V)
automatic choke
1970 4V Autolite AF-42 .032"-.036"     2.185"- 2.195" 1.7045"- 1.7145" Autolite 4300-A (4V)
Squarebore auto choke
1971 2V Autolite ARF-42 .032"-.036" 24-29 (manual)
26-31 (automatic)		 .017" 1.9025"- 1.9175" 1.533"- 1.548" Autolite 2300- (2V)
automatic choke
1971 4V Autolite AF-42 .032"-.036"     2.185"- 2.195" 1.7045"- 1.7145" Autolite 4300-A (4V)
Squarebore auto choke
1972 2v Autolite ARF-42 .032"-.036" 24-29 (manual)
26-31 (automatic)		 .017" 1.9025"- 1.9175" 1.533"- 1.548" Autolite 2300- (2V)
automatic choke
1972 4V Autolite AF-42 .032"-.036"     2.185"- 2.195" 1.7045"- 1.7145" Autolite 4300-A (4V)
Squarebore auto choke
1972 CJ Autolite ARF-42 .032"-.036"     2.185"- 2.195" 1.7045"- 1.7145" Autolite 4300-A (4V)
Squarebore auto choke
1973 HO Autolite ARF-42 .032"-.036"     2.185"- 2.195" 1.7045"- 1.7145" Autolite 4300-D (4V)
Spread bore auto choke