Really basic head questions
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
Really basic head questions
I've been reading the flurry of posts the last few days on the Aussie heads, and it's raised a couple of very basic questions that stem more from ignorance than anything else. I warned you.
What's the difference between 2V and 4V heads? Does it have anything to do with the engine having a 2V or a 4V carb?
And what's the difference between closed chambered and open chambered heads?
Thanks!
Moderator
Joined: Jan 2001
Posts: 56,997
Likes: 2,742
From: Virginia
Really basic head questions
Yes 2v is 2 barrel and 4v is 4 barrel. The reason this comes up with cleveland type engines is Ford had a different casting depending on if it had a 2 barrel carb or a 4 barrel. The 4 barrel heads have very large ports and valves.
Ford and other auto manufacturers also change the shape of the combustion chamber where the valves and sparkplug are. They do this mainly to change the compression ratio of the engine, whether it is 2v or 4v. The small chambers usually have just enough room for the valves and sparkplug and these are referred to as "closed chambered" heads. The later heads have a large round chamber and these are "open chambered" heads. The large chamber will reduce the compression ratio of the engine while the closed chamber will raise the compression ratio.
Ford and other auto manufacturers also change the shape of the combustion chamber where the valves and sparkplug are. They do this mainly to change the compression ratio of the engine, whether it is 2v or 4v. The small chambers usually have just enough room for the valves and sparkplug and these are referred to as "closed chambered" heads. The later heads have a large round chamber and these are "open chambered" heads. The large chamber will reduce the compression ratio of the engine while the closed chamber will raise the compression ratio.
Elder User
Joined: Sep 2001
Posts: 887
Likes: 1
From: Jax FL
Really basic head questions
in the old days yes. the 2v heads came with 2 bbl carbs and intakes, the 4v, like treatment with 4bbl carbs. the big difference is the head chambers and ports. All US. 2v heads are open chambered heads and have smaller ports. While about half of 4v heads have closed chambered heads and the port size is much larger. here are the differences between 2v and 4v clsed chambered heads
2V 4V
vavles 2.05/1.65 - 2.19/1.71
chambers @78 - @62
intake ports 1.9 x 1.28 - 2.38 x 1.63
Now adays, one can get intakes with 4bbl carbs on 2V heads. The Aussie heads give the 4V closed chambered heads with the 2V ports. This makes a killer street setup.
2V 4V
vavles 2.05/1.65 - 2.19/1.71
chambers @78 - @62
intake ports 1.9 x 1.28 - 2.38 x 1.63
Now adays, one can get intakes with 4bbl carbs on 2V heads. The Aussie heads give the 4V closed chambered heads with the 2V ports. This makes a killer street setup.
