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Discussion Starter #1
I have heard so many opinions from so many people regarding this question that my head is about to go critical. To tell you the truth, I am a slight bit worried. I want the baddest engine I can have... for the money. I will be doing the same maching work on the heads regardless of whether they are Aussie closed or 4V closed. There is NO cost analysis to be done... I just need to know ONE thing... which ones am I gonna like better? I am building my car to be a brute. I plan to visit the local track (drag), but I do NOT want to build a drag car. I will have a Toploader (wide) and I currently have a 3.00 traction lock rear. The only variable here is port and valve size. Assume all else equal, and epoxying the 4V ports is not an option. What would you go with? Will the Aussies not produce a "screamer?" Will the 4V REALLY disappoint between the stoplights?

Simple question of opinion and tastes... as I have no experience with either head.
 
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Im interested! As soon as I come by some aussies with a good price I am going to attempt the swap. I have done alot of reasearch about the aussies and Jason(nosaj) has helped me out quite a bit. It seems the problems that I am going to face are deck clearance to achieve the proper quench affect, and whether or not 91 octane cali gas will tollerate the 11.1 or so compression. I have read that alot of intake duration will bleed of some of the compression at lower rpm and will prevent detonation. Im also wondering if the aussies would benefit from larger 4v valves? Let us know what you do. Should be interesting. Josh
 

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I'm not a Cleveland expert, but I've always read that the 2V Aussies were the most desireable for the street. That would imply that the low and mid-range is decent, but the top wouldn't be the same as the 4V heads.

I'm not sure, but sounds like this is a case of "can't have your cake and eat it too!"

For a car spending 90% of it's time on the steet, I would be building torque. Which is what I'm doing with my 331 build.
 
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Well, that site just about sumned it up I would say.
Thanks. I am now that much smarter. A good day.

JB
 

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Discussion Starter #10
I want my cake, with icing. I want to eat it, drink it, smear it all over my body... err... sorry about that.
 

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That article is pretty good. I have ported Aussies with roller rockers setting in my garage waiting to be installed. I need to get a ring job before I put the heads on and I need to figure out the right cam for the change to the ported intake ports to work with stock manifolds. I spoke to Jeff Ford of Mustang Monthly when I was making the decision and he said, If you go for the 2v Aussie upgrade don't put the 4v larger intake valves. Leave in the 2.04's. He tried it and didn't like it. I didn't ask for this bit of info, he volunteered it. Good enough for me.
In my humble opinion you will get a tire burning monster either way. Getting it hooked up is going to be the biggest problem. Yes most people agree that the Aussies will give you a better kick from a slow rolling start compared to the 4v, but the 4v will turn more rpms that will lead to higher speeds at the end of the track. More money to spend on a super solid bottom end. I opted for a higher stall converter on my AOD and the Aussies. Cheaper and more street friendly and fun.

Exhaust gas is the key. Cam lift and duration plus headers. What is the math? I wish I knew. Will figure it out when I get there. You can also play with the compression by using thicker head gaskets. Watch out for intake matching if you mess with thicher head gakets are decked heads.

By the way. How do you make your signature picture a link?
 

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Well for practical uses the Aussie heads are much better all around......

The 4V heads are only good in the mid to upper rpms.

The aussie heads meanwhile flow much better all around due to the smaller port design and smaller "unshrouded" valves (when valves are almost up against the edge of combustion chamber they are shrouded.

This is a bad thing for flow velocity when the valve opens up. (it has a bad effect on the swirl thus the velocity)

Get the Aussie heads and have the complete portwork done to them, Bowls (others call em valve pockets) transition and ports
a 3 angle valve job will only help flow.

The valve sizes on the Aussie heads should suffice. 2.10 intake
and I can't remember exh size but they should be an awesome combo with good compression and good cam choice.

Bigger ports don't always mean more airflow....
Well designed ports and good sized valves will always outflow the 2.25int/1.71 combo.....(this is why the Boss engines were only good at high rpms)

the Aussies will give you usable horsepower (low end torque) with excellent flow potential (given that you have them ported.)

enjoy!!
 

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I have my opinions and like the 4v heads. A aussie head properly ported would run hard. 2v heads tend to start laying down at about 5000. I've only messed with open chamber 2v's and know that the 4v chambers rule. It's my thinking that who needs 500 pound feet of torque @1000 RPM. I run 4v's and can tell you don't beleive all you hear or read. My car has got 315 or more rear wheel horse power and still get 18 MPG with a stock drive train. I don't think that it's so much loosing low end as gaining top end,some people don't know the difference. I put my motor together in 92 and gas has changed if I were you think about dropping compression a point.
 

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HAVE YOU SLAPPED A TREEHUGGER TODAY?
------------------------
Not today but I will be visiting my mom tomorrow in Santa Cruz....
:)
 
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