[DeTomaso] Cleveland 2v vs 4v heads

Göran Malmberg hemipanter at hemipanter.se
Thu Mar 6 02:34:44 EST 2008


Does anyone know about a serious test using 2 vs 4V heads?
This could have been done in four ways.
1. Exactely the same engine, and exhaust, carb, cam etc.
2. The enine is built to suit the heads.
Both example should use the same rpm field, say 5000 rpm hp.
Then a slightley hotter version for say 6500 rpm hp.

I have been driving a 2V hed equipped Pantera using a 240 @050 cam
and Hall big bore headers and a 750 Holley, and I was not that impressed
by the performance at any rpm even if not bad. On the strip it managed
14,5 sec.
I had a fast look at the webb regarding 2V 1970 Fords, and neither of
the 2V head showed better Tq than the 4V engines. The sbc LT1 and
351 Boss had almost the same Tq at the same rpm 4000.

Aside from this I should like the 2V heads to have located the ports
at the height of the top of the 4V heads, not at their bottoms.
Goran



----- Original Message ----- 
From: "michael at michaelshortt.com" <michaelsavga at gmail.com>
To: "Ken Green" <kenn_green at yahoo.com>
Cc: <detomaso at realbig.com>; <HOTPANTERA at aol.com>
Sent: Thursday, March 06, 2008 4:38 AM
Subject: Re: [DeTomaso] Cleveland 2v vs 4v heads


> Here are some links to look at, as with anything regarding our cars, lots 
> of
> opinions.
>
> You can pick up a set of Yates heads too, not cheap, but worth it.
>
> Michael in Savannah
>
> http://home.comcast.net/~jelerath/mustang/Specs/heads-fr.html
>
>
> Let's look at some comparisons. If you have any doubt about the Cleveland
> heads breathing well, compare the valve diameters to the 390, 427, 428 and
> even the 460 Police Interceptor. The Cleveland 4V has a bigger intake 
> valve
> than any of the other engines except the 460 Police Interceptor! The 351C 
> 4V
> exhaust valve is only 0.020" smaller diameter than the 460 PI, and only
> 0.010" smaller than the high performance 427. Even the lowly 351C 2V has
> intake valves larger than the high performance 390's and 428's, and the
> exhausts are larger than all 390's and some 427's, 428's and 460's.
>
> Looking at the Intake Port of the 351C 2V, you will see that it is larger
> than the 390, 428 and some 427's and 460's (multiply the two dimensions).
> So, while the displacement in the 351C is obviously less than the 390, 
> 427,
> 428 and 460, it is designed to breathe *better* than the others and it has 
> *
> fewer* cubic inches to breathe (fill and empty). This is why the 
> Clevelands
> Rock!
>
> If you want to compare the 351W to the 351C, you will see that the 351W
> looks more like a 302 head and the 351C looks more like a standard 427 or
> 428 head!
> The 2v heads actually work better on the street than 4v heads do, and four
> barrel aftermarket intakes for 2v heads were commonly available from 
> several
> different makers, such as Edelbrock, Offy and Weiand.
>
> The 4v chamber makes the Aussie head the "hot set-up" for street 
> Clevelands,
> and headers are the same as other 351c or 351/400m engines. Should make a
> strong running combo for ya!
>
> 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" (1971-1974), R-code "Boss" 351 (1971), and
> R-code 351 "HO" (1972) versions have 4-bolt mains although all 335 series
> engines (351C/351M/400) have space for them even in 2-bolt main form. The
> main difference between 351C/351M/400 engines is connecting rod length and
> main bearing size. The 351M/400 engines have the largest bearing size and
> the tallest deck height while sharing the 429/460 bell
> housing<http://en.wikipedia.org/wiki/Bell_housing>pattern. The 351C
> engine has a medium main bearing size and shorter
> connecting rods than the 351W and the 351M/400 while retaining the SBF
> engine mount locations and bell housing pattern. The 400 engine has the
> longest stroke of any SBF or 335 series engine.
>
> All of the 351C and 351M/400 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.
>
> [edit<http://en.wikipedia.org/w/index.php?title=Ford_335_engine&action=edit&section=3>
> ] H-code [image: 1973 H-code 2V 351
> Cleveland]<http://en.wikipedia.org/wiki/Image:1973_Ford_Mustang_convertible_351-2V_Cleveland.JPG>
> <http://en.wikipedia.org/wiki/Image:1973_Ford_Mustang_convertible_351-2V_Cleveland.JPG>
> 1973 H-code 2V 351 Cleveland
>
> The majority of 351 Cleveland engines are H-code 2V (2-venturi carburetor)
> versions with low compression. They were produced from 1970 through 1974 
> and
> were used on a variety of Ford models, from compact to intermediate. These
> engines produced about 270 horsepower.
>
> [edit<http://en.wikipedia.org/w/index.php?title=Ford_335_engine&action=edit&section=4>
> ] M-code
>
> The M-code version was produced from 1970 through 1971. Both years offered
> quench heads but 1970 offered a slightly higher (advertised) 11.4:1 
> compression
> ratio <http://en.wikipedia.org/wiki/Compression_ratio> whereas in 1971 the
> chamber was opened up slightly reducing the advertised compression to 
> 10.7:1.
> The 1970 4V head is identified with the proper date code casting and a "4"
> cast on the upper corner of the head. The 1971 4V head is identified with 
> a
> "4*" (four-dot) casting at the same location. 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<http://en.wikipedia.org/w/index.php?title=Ford_335_engine&action=edit&section=5>
> ] 1971 R-code (Boss 351) *See also Ford Boss 351
> engine<http://en.wikipedia.org/wiki/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<http://en.wikipedia.org/w/index.php?title=Ford_335_engine&action=edit&section=6>
> ] 1972 R-code
>
> The R-code 351 Cleveland for 1972 was considerably different. It had 
> reduced
> compression for emissions compliance and used open-chamber heads. It had a
> Hydraulic camshaft, however a four barrel carburetor was retained. It
> produced 300 hp (207 kW) using the new SAE net system.
>
> [edit<http://en.wikipedia.org/w/index.php?title=Ford_335_engine&action=edit&section=7>
> ] Q-code (Cobra-Jet)
>
> The Q-code "351 Cobra Jet" version was produced from May 1971 through the
> 1974 model year. It was a low-compression design that included 
> open-chamber
> "4V" heads, a special intake manifold, special hi-lift long duration
> hydraulic camshaft, special valve springs and dampers, a 750 CFM 4300-D
> Motorcraft Carburetor, dual-point distributor, and 4-bolt main bearing 
> caps.
> It was rated at 280 hp (198 kW) (SAE net) for 1972 when installed in the
> Mustang <http://en.wikipedia.org/wiki/Ford_Mustang> and 280 hp in the Ford
> Torino <http://en.wikipedia.org/wiki/Ford_Torino> and Mercury
> Montego<http://en.wikipedia.org/wiki/Mercury_Montego>.
> The hp rating changed in 1973 to 246 for the 4-barrel, but showed a higher
> rating for the Cobra Jet, 264 hp. Being under the net ratings system, the
> engine was considered one of the sportiest of 1973, and is among the last 
> of
> the muscle-era motors. Hp ratings dropped to 246 hp (183 kW) for the
> intermediate Ford and Mercurys for 1973. The 351 CJ was rated at 265 hp in
> 1974 and was only installed in the Ford
> Torino<http://en.wikipedia.org/wiki/Ford_Torino>,
> Mercury Montego <http://en.wikipedia.org/wiki/Mercury_Montego> and the 
> Mercury
> Cougar <http://en.wikipedia.org/wiki/Mercury_Cougar>.
>
>
>
> On Wed, Mar 5, 2008 at 9:37 PM, Ken Green <kenn_green at yahoo.com> wrote:
>
>> A "HOTPANTERA" would definitely have 4V heads.
>>
>>  Ken
>>
>> HOTPANTERA at aol.com wrote:
>>  I was wonder what the thoughts were between the 2v heads or the 4v heads
>> for
>> a Pantera? What about a 1984 Block? Thanks for any help
>>
>>
>>
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>
>
> -- 
> Michael L. Shortt
> Savannah, Georgia
> www.michaelshortt.com
> michael at michaelshortt.com
>
>
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