jes72mustang

OK I saw the thread below about 302 vs BOSS 302, and wanted to ask the same thing about the 351C Cobra Jet vs a plain 351C.

What are the differences?

jarrettdad

I've never heard of a 351 CJ.... didn't know they exist.

72rustang

This was the first site that showed up on a google search for "351 CJ". I have no idea whether or not this info is accurate.

http://phystutor.tripod.com/stang/en...cleveland.html

jes72mustang

351 Cobra jets were Clevelands, and were the Q code engines in 71-73 cars.

JBradley500

Can someone explain the difference to me between the 351c and Boss 351's??

THUMPIN455

adjustable valve train and a different cam. Plus 4 bolt mains in the BOSS351..

rwh129

The 351 CJ

Q-code (Cobra-Jet)
The Q-code "351 Cobra Jet" version was produced from May 1971 through the end of 1973. It was a low-compression version of the 4V design with the cheaper cast-iron intake manifold but included a special camshaft, dual-point distributor, and 4-bolt main bearing caps. 266 hp (198 kW) (SAE net) was recorded for 1972 which fell to 246 hp (183 kW) for 1973.

The 351 Cleveland was introduced in 1970 as Ford's new muscle car engine and was built through the end of the 1974 model year. It incorporated elements learned on the 385 big-block series and the Boss 302, particularly the poly-angle combustion chambers with canted valves and the thin-wall casting technology.

Both a 4V (4-barrel carburetor) performance version and a 2V (2-barrel carburetor) basic version were built, both with 2 valves per cylinder. The latter had a different cylinder head with smaller valves, smaller ports, and open combustion chambers to suit its intended applications.

Only the Q-code 351 "Cobra Jet" (1971-1973), R-code "Boss" 351 (1971), and R-code 351 "HO" (1972) versions have 4-bolt mains although all 335 series engines (351C/351M/400M) have space for them even in 2-bolt main form. The main difference between 351W/351C/351M/400M engines is connecting rod length and main bearing size. The 351/400M engines have the largest bearing size and the tallest deck height while sharing the 460 bell housing pattern. The 351C engine has a medium main bearing size and shorter connecting rods than the 351W and the 351/400M while retaining the SBF bellhousing pattern. The 400M engine has the longest stroke of any SBF or 335 series engine.

All of the 351C and 351/400M engines differ from the 302/351W by having an integrated timing cover casting in the front of the block to which the radiator hose connects.

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H-code

1973 H-code 2V 351 ClevelandThe majority of 351 Cleveland engines are H-code 2V (2-venturi carburettor) versions with low compression. These were produced from 1970 through 1974 and were used on a variety of Ford models from compact to intermediate.

[edit]
M-code
The M-code version was produced from 1970 through 1971. It used a high 10.7:1 compression ratio with "4V" quad-barrel carburetors and the quench head-design 4V heads. Hydraulic lifters were also specified, with the M-code producing about 300 hp (224 kW). 2-bolt main caps were used along with a cheaper cast iron intake manifold.

[edit]
1971 R-code (Boss 351)
See also Ford Boss 351 engine
The 1971 R-code "Boss 351" used higher compression (11.7:1) with the quench head 4V heads, solid lifters, an aluminum intake manifold, and 4-bolt main caps. It produced about 330 hp (246 kW).

[edit]
1972 R-code
The R-code 351 Cleveland for 1972 was somewhat different. It reduced compression for emissions compliance and used open-chamber heads, although the solid lifters were retained. It produced 277 hp (207 kW) using the new SAE net system.


http://en.wikipedia.org/wiki/Ford_Cleveland_engine

Fajr22

The 351 cobra jet came out in 1971, and differs from the boss. 351 and standard 351 2v Cleveland. The Boss, CJ and HO all have 4 bolt mains, unlike the 2v which has 2bolt mains and smaller cylinder heads. The HO and the Boss have aluminum 4v intakes and adjustable rockers with guide plates where the CJ does not. The cams are different as well. The boss and HO are the same motors, just different years, due to the cease of production of the bosses in 1971

Power wise they rank in this order

BOSS 351-----1971 only
351c HO--------1972 only
351c CJ--------- 1971-1973
351c 4V--------- 1970-1973(USA)
351c 2V--------- 1970-1975