• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Dumb question here
#1
What is the difference between a 351C 4v and 351C 4v Cobra Jet? There is a slight horse power variance just wondering where it comes from....what makes it a Cobta Jet? (More dumb questions to follow).

[Image: 33vc6z8.jpg]
Vehicles: 1972 Sprint Sportsroof CJ
2011 F-150, Lariat 4x4, Super Crew
  Reply
#2
http://www.carmemories.com/cgi-bin/viewe...nce_id=505


One is the heads are different CC in the chambers.
  Reply
#3
Among other things, different compression ratios and certain upgraded parts. http://en.wikipedia.org/wiki/Ford_335_engine

P.S., there are no dumb questions. If there were, I'd be the king of dumb questions. I think I'll make that my new signature: KODQ!

Steve



[Image: 25yvyp3.jpg]
  Reply
#4
I will give it a "shot."

The 351C initially came out in 1970 in two (2) versions, the 2V and a 4V. The 2V had open chamber heads while the 4V had quench chamber heads. I believe that both versions had 2-bolt main caps.

In 1971, every 351C that received a 4V Carburetor received 4-bolt mains. The 2V and the 4V headed motors were continued. In mid-year (May 1971), the 351CJ was released. It had open chamber heads and 4-bolt main caps. It also had a hotter hydraulic camshaft than the standard 4V motor. There were approximately 144 Mustangs built with 351CJ engines in 1971.

Also released in 1971 was the Boss 351 which was essentially the same as the 351 4V except it had solid (mechanical) lifters and camshaft. It also received the quench chamber heads and 4-bolt main caps.

In 1972, the 4V designation was dropped and all 10,249 4V Mustangs produced were actually Cobra Jets. These motors were essentially the same as the 351CJ that were released in 1971.

Also released in 1972 was the 351 HO (398 Mustangs) which replaced the Boss 351. It differed from the Boss 351 primarily with the use of open chamber heads. It also had a milder camshaft with less duration and a little more lift.

In 1973, the 351CJ continued as a 266HP (Net) unit in the Mustangs.

Hope this helps.

BT

Do the RIGHT thing.
  Reply
#5
cobra3073;19072 Wrote:I will give it a "shot."

The 351C initially came out in 1970 in two (2) versions, the 2V and a 4V. The 2V had open chamber heads while the 4V had quench chamber heads. I believe that both versions had 2-bolt main caps.

In 1971, every 351C that received a 4V Carburetor received 4-bolt mains. The 2V and the 4V headed motors were continued. In mid-year (May 1971), the 351CJ was released. It had open chamber heads and 4-bolt main caps. It also had a hotter hydraulic camshaft than the standard 4V motor. There were approximately 144 Mustangs built with 351CJ engines in 1971.

Also released in 1971 was the Boss 351 which was essentially the same as the 351 4V except it had solid (mechanical) lifters and camshaft. It also received the quench chamber heads and 4-bolt main caps.

In 1972, the 4V designation was dropped and all 10,249 4V Mustangs produced were actually Cobra Jets. These motors were essentially the same as the 351CJ that were released in 1971.

Also released in 1972 was the 351 HO (398 Mustangs) replaced the Boss 351. It differed from the Boss 351 primarily with the use of open chamber heads. It also had a milder camshaft with a less duration and a little more lift.

In 1973, the 351CJ continued as a 266HP (Net) unit in the Mustangs.

Hope this helps.

BT

Thats a real thorough answer!

[Image: 25rnz1y.jpg]

~Buddy
  Reply
#6
cobra3073;19072 Wrote:I will give it a "shot."

The 351C initially came out in 1970 in two (2) versions, the 2V and a 4V. The 2V had open chamber heads while the 4V had quench chamber heads. I believe that both versions had 2-bolt main caps.

In 1971, every 351C that received a 4V Carburetor received 4-bolt mains. The 2V and the 4V headed motors were continued. In mid-year (May 1971), the 351CJ was released. It had open chamber heads and 4-bolt main caps. It also had a hotter hydraulic camshaft than the standard 4V motor. There were approximately 144 Mustangs built with 351CJ engines in 1971.

Also released in 1971 was the Boss 351 which was essentially the same as the 351 4V except it had solid (mechanical) lifters and camshaft. It also received the quench chamber heads and 4-bolt main caps.

In 1972, the 4V designation was dropped and all 10,249 4V Mustangs produced were actually Cobra Jets. These motors were essentially the same as the 351CJ that were released in 1971.

Also released in 1972 was the 351 HO (398 Mustangs) replaced the Boss 351. It differed from the Boss 351 primarily with the use of open chamber heads. It also had a milder camshaft with a less duration and a little more lift.

In 1973, the 351CJ continued as a 266HP (Net) unit in the Mustangs.

Hope this helps.

BT

When I got my 351C 2v the guy had a set of 4V heads in the trunk. I had the rocker bosses (?? rocker bolt points) cut down and installed adjustable roller tip rockers. How can I tell what kind of 4V heads they are?
  Reply
#7
docweld;19106 Wrote:
cobra3073;19072 Wrote:I will give it a "shot."

The 351C initially came out in 1970 in two (2) versions, the 2V and a 4V. The 2V had open chamber heads while the 4V had quench chamber heads. I believe that both versions had 2-bolt main caps.

In 1971, every 351C that received a 4V Carburetor received 4-bolt mains. The 2V and the 4V headed motors were continued. In mid-year (May 1971), the 351CJ was released. It had open chamber heads and 4-bolt main caps. It also had a hotter hydraulic camshaft than the standard 4V motor. There were approximately 144 Mustangs built with 351CJ engines in 1971.

Also released in 1971 was the Boss 351 which was essentially the same as the 351 4V except it had solid (mechanical) lifters and camshaft. It also received the quench chamber heads and 4-bolt main caps.

In 1972, the 4V designation was dropped and all 10,249 4V Mustangs produced were actually Cobra Jets. These motors were essentially the same as the 351CJ that were released in 1971.

Also released in 1972 was the 351 HO (398 Mustangs) replaced the Boss 351. It differed from the Boss 351 primarily with the use of open chamber heads. It also had a milder camshaft with a less duration and a little more lift.

In 1973, the 351CJ continued as a 266HP (Net) unit in the Mustangs.

Hope this helps.

BT

When I got my 351C 2v the guy had a set of 4V heads in the trunk. I had the rocker bosses (?? rocker bolt points) cut down and installed adjustable roller tip rockers. How can I tell what kind of 4V heads they are?

I can answer this one. The combustion chambers are pretty distinctive between the different heads. The head on the left is open chamber (71-73), the head on the right is closed chamber (70-71)

[Image: Clevel1.jpg]

[Image: 25rnz1y.jpg]

~Buddy
  Reply
#8
I don't know about anyone else, but I definitely learned something by reading this.

[Image: 386_07_10_13_5_58_42.jpeg]
My Mustangs:
71 M-code Mach 1, Medium Blue/White Sport, 4R70W, 3L50, Factory Ram Air.
72 Q-code Mach 1, Pewter/Black Sport, 4-spd, 3L25.
73 F-code Convertible, Planned: color TBD/Black top/White Int., 351C, 5-spd, 3L50.
65 Convertible, Britney Blue/White/White, more modified than original.
05 Convertible, Legend Lime/Tan/Tan, future classic??
  Reply
#9
Widowmaker00;19109 Wrote:
docweld;19106 Wrote:
cobra3073;19072 Wrote:I will give it a "shot."

The 351C initially came out in 1970 in two (2) versions, the 2V and a 4V. The 2V had open chamber heads while the 4V had quench chamber heads. I believe that both versions had 2-bolt main caps.

In 1971, every 351C that received a 4V Carburetor received 4-bolt mains. The 2V and the 4V headed motors were continued. In mid-year (May 1971), the 351CJ was released. It had open chamber heads and 4-bolt main caps. It also had a hotter hydraulic camshaft than the standard 4V motor. There were approximately 144 Mustangs built with 351CJ engines in 1971.

Also released in 1971 was the Boss 351 which was essentially the same as the 351 4V except it had solid (mechanical) lifters and camshaft. It also received the quench chamber heads and 4-bolt main caps.

In 1972, the 4V designation was dropped and all 10,249 4V Mustangs produced were actually Cobra Jets. These motors were essentially the same as the 351CJ that were released in 1971.

Also released in 1972 was the 351 HO (398 Mustangs) replaced the Boss 351. It differed from the Boss 351 primarily with the use of open chamber heads. It also had a milder camshaft with a less duration and a little more lift.

In 1973, the 351CJ continued as a 266HP (Net) unit in the Mustangs.

Hope this helps.

BT

When I got my 351C 2v the guy had a set of 4V heads in the trunk. I had the rocker bosses (?? rocker bolt points) cut down and installed adjustable roller tip rockers. How can I tell what kind of 4V heads they are?

I can answer this one. The combustion chambers are pretty distinctive between the different heads. The head on the left is open chamber (71-73), the head on the right is closed chamber (70-71)

[Image: Clevel1.jpg]

in this pic the right one is my old 2V head and the left is the new 4V head. is the closed better then to open? I would think so.


Attached Files Thumbnail(s)
   
  Reply
#10
Yes yes and a maybe as far as better, depends on what you are doing. Closed chamber will raise your compression ratio. get the numbers off the head and we can tell you exactly what they are.
  Reply
Share Thread:  


Possibly Related Threads...
Thread Author Replies Views Last Post
  Rental Mustang question... soonerbillz 0 164 05-10-2018, 11:57 AM
Last Post: soonerbillz
  Another Marti report question: Steel Guard Rails? Mustangfeverrr 2 550 05-30-2017, 05:17 PM
Last Post: Mustangfeverrr
  1972 Mustang Convertible question Dcerny 8 788 04-15-2017, 07:43 AM
Last Post: Dcerny
  73 power window question 6972boss 2 451 12-13-2016, 03:51 PM
Last Post: Carolina_Mountain_Mustangs
  1973 Mach 1 Hood Paint Question griffbl 4 851 11-08-2016, 01:10 PM
Last Post: griffbl
  71 Mustang question mwilson7 6 760 11-04-2016, 08:09 PM
Last Post: donkost
  Keeping her original question. Cole 4 551 05-27-2016, 11:43 AM
Last Post: Cole
  Exhaust question 1hotboss 1 660 09-24-2015, 11:52 AM
Last Post: jbojo



Users browsing this thread: 1 Guest(s)