2v or 4v heads?

[Don65Stang]

not at all, i think that is a myth caused by people trying to run them with 2.75 rear ends or 1050 carburetors or otherwise treating the engine like a chevy. That or people wanting top dollar for 2V heads

You are on the right track and should be pleased as long as your compression ratio is reasonable (Over 9.5 and under 11)

This and what 72HCODE said in the above post are spot on advice.

Build a 4V closed chamber head to '71 M-code factory specs and you'll have a great street engine.

Build a 4V open chamber head to '72 Q-code factory specs and you'll have a great street engine.

Use at least 3.25 rear gears with a 4v engine.

Both of the above may not the best out there vs using a new cam grind but the factory engines are proven performers and always put a smile on my face.

 

[hyena429]

"if you want a drag car your going with closed camber 4V heads."

Counts what style of drag racing you going to do..Most of the bad boys run open chambers...even john force runs open on his nitro...Close chambered valve shrouding become a big issue when dealing with insaine hp..Reason why hemi heads so popular with there big open chambers...Get more ping and detonate more, and get more heat with closed chambered heads...There are pro's and cons with each head design...Both version of the 4v head can be built to handle just fine on the street and drag racing.

 

[cazsper]

Now I'm wondering if a big bore stroked Windsor (427cid) with AFR-220 heads wouldn't be a better choice..

 

[Jeff73Mach1]

It certainly wouldn't be a bad choice-but better?

 

[cazsper]

Well, with all the questionable choices (4v vs 2v, open vs closed). It's enough to make someone go crazy.

 

[wwhite72]

Or, it provides you with many choices in which to build the engine that performs the way you want it to. All depends on how you choose to look at it. When our cars were new people wanted choices and were willing to take responsiblty for their choices. Was a better time, and a better country then.

 

[Don65Stang]

Well, with all the questionable choices (4v vs 2v, open vs closed). It's enough to make someone go crazy.

All the US 2v are open chamber BTW. Aussie 2v heads are closed.

I have all versions of the US heads. They all are fine. I prefer the 4v closed chamber heads but either really is fine. I suggest you take whatever ones you have and build the rest of the engine accordingly. Every engine build has to be done so all the components compliment all the other items. Use at least 3.25 rear gears with the 4v engines.

 

[cobra3073]

The guys are "spot on" in my opinion.

ANY of the heads will work just fine based on your stated objectives. It is just a matter of building the motor as a complete package.

My $.02.

BT

 

[mach71351c]

To start with, the engine in my '73 Mach-1 is a 4v Cleveland. If I keep the small block, I'm thinking of a 393c making around 450ish hp. This is a street only, daily driver. I'm thinking:

393C, 228/234 @ .050" hyd/roller cam, Edelbrock air gap intake, holley 750cfm, Sanderson shorty headers and 2 1/2" ,full length exhaust. Should I use the 4v headers or would that be to much head for that particular setup? I'm only asking because I've been told that the 4v heads are better suited for high RPMs. I'm planning on a tremec 5-speed with 3.50:1 gears.

I your going to run 3.50 gears the so called better low end of the 2v head is a non factor over the 4V head.( stock or built ) But when running 3.50s and the 2v head gives up a 5k at best the 4V head will still be putting a smile on your face all the way past 6500. Both head will need a good quality valve train installed that's a given. But there is no point in spending money porting polishing heads that are prone to detonation. I say work with the heads you already have.

 

[wwhite72]

Aussie 2v heads are closed chamber heads. From my personal experience the open chamber heads are more prone to detonation than the closed chamber heads.

 

[will e]

If I was going with a 5 speed I would consider going with gears in the 3.7 range.

What's the ratios on that 5 speed?

I would go 4v cc

I run 4v cc on my ride (see specs in sig). The transmission has a stock 2v converter in it, I am going to swap it out for something with a little higher stall speed. I have run 2v and 4v in the car and I can tell you 4v is much funner when you are getting on it. It puts a smile on my face EVERY TIME.

 

[cazsper]

As for the transmission, I'm mostly concerned with being able to drive it on the freeway. The 5th gear is .68..

 

[marks73]

"if you want a drag car your going with closed camber 4V heads."

Counts what style of drag racing you going to do..Most of the bad boys run open chambers...even john force runs open on his nitro...Close chambered valve shrouding become a big issue when dealing with insaine hp..Reason why hemi heads so popular with there big open chambers...Get more ping and detonate more, and get more heat with closed chambered heads...There are pro's and cons with each head design...Both version of the 4v head can be built to handle just fine on the street and drag racing.

If running nitrox, superchargers or blowers you want to lower your compression as low as 7:1. A pump gas naturally asperiated engine loves closed chambers as long as you don't exceed 11:1 compression. You'de love 4V CC heads.

 

[hyena429]

"if you want a drag car your going with closed camber 4V heads."

Counts what style of drag racing you going to do..Most of the bad boys run open chambers...even john force runs open on his nitro...Close chambered valve shrouding become a big issue when dealing with insaine hp..Reason why hemi heads so popular with there big open chambers...Get more ping and detonate more, and get more heat with closed chambered heads...There are pro's and cons with each head design...Both version of the 4v head can be built to handle just fine on the street and drag racing.

If running nitrox, superchargers or blowers you want to lower your compression as low as 7:1. A pump gas naturally asperiated engine loves closed chambers as long as you don't exceed 11:1 compression. You'de love 4V CC heads.

Never said i hated 4v closed...just standing up for 4v opens..hehe.....4v open can do just as well on the strip.......You can get plenty of compression out of 4v opens with pop up pistons....If all you can find is 4v open they will do a good job on a high performance motor, if you know how to set them up right...Launch it right...will flow good with out the shrouding...Specialy if you set it up for forced induction or something...4v opens set up right do good on the drag strip.

No matter if its 4v open or closed... both heads will be moody at low rpm's, specialy when built with big cam and headers.....Neither head does well below 2,500 rpms...both shine at high rpm's..Both can be really good race heads in my book.

 

[will e]

As for the transmission, I'm mostly concerned with being able to drive it on the freeway. The 5th gear is .68..

That would be nice with a 3.7x in my opinion. What are the other gears?

 

[Mister 4x4]

Don't waste your time or money on 2v heads. The amount of effort and money it takes to get 400+ out of 2v heads is just not worth it. I was one of those guys that thought 2v heads where better for the street.:-/ Then I tried 4V heads in the same car. I will never go back. The amount of low end that the 2v head maybe,"maybe" has over the 4V does not out way the med to high range power the 4V head has.

As one of those guys who indeed wasted the time and money on the 2V heads, you just made me cry.

I dont know if its a waste. I had 2v heads and had to work with what I had. i did put some money into them. All new valves, guides, cut for screw in studs, good bit of porting and port matching done. They seemed to flow pretty darn good for 2v heads. I ended up going with the afd 4v heads now and love them, but my 2v heads worked well. i was a little north of 400hp with the 2v. I sold them to theJ. Dont know if he got them on his car yet but i think he will be really happy with the setup that i sold him.

Nah, I know it's not a waste... because I'm actually going for a daily driver with burn-out capabilities. I just wanted to poke back a little. rofl

 

[mach71351c]

As one of those guys who indeed wasted the time and money on the 2V heads, you just made me cry.

I dont know if its a waste. I had 2v heads and had to work with what I had. i did put some money into them. All new valves, guides, cut for screw in studs, good bit of porting and port matching done. They seemed to flow pretty darn good for 2v heads. I ended up going with the afd 4v heads now and love them, but my 2v heads worked well. i was a little north of 400hp with the 2v. I sold them to theJ. Dont know if he got them on his car yet but i think he will be really happy with the setup that i sold him.

Nah, I know it's not a waste... because I'm actually going for a daily driver with burn-out capabilities. I just wanted to poke back a little. rofl

I love burn-out capabilities!

 

[JimNiki]

I trust they are all in the name of science!

 

[JamesS]

If you want help shipping 2V Closed chamber Aussie heads to the US, just PM me.

There are some stupid numbers being pulled out of very stock builds here with CC Aussie heads. As in 550 plus HP without the bottle.

With a stroker I would probably use your 4v cc heads. Throw some port stuffers in if you think it makes a big difference. I wouldn't bother at first.

Apparently the Edelbrock air gap intake is the hot thing for a street intake at the moment.

Have fun, nothing sounds better than a 351c screaming like a cut cat...please use roller rockers and good valve train gear!

James