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Old 09-21-2006, 04:14 PM
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400 Aussie

I have a 1976 cougar with a 400M. I have always thought the 400 was very underrated when it came to performance. Everyone knows you can put 4V Cleveland heads on it but the knock I always heard was the main journals were not small like the 351C. It has 2.75 in journals and the 400 has 3.00in. meaning more friction. The thing that always confused me is that both 400M and Windsor block have 3.000 in. main journals. The 351 W has become the darling of the Ford set. It is being stroked out to 427 and has gobs of horsepower. What’s the difference? I know there are some physical differences but are they so important to lose 250-300 horsepower? Mine has been overbored.030 and is 408 inches by my calculations. Why is it always regarded as a truck engine suitable only for low-end torque?

Recently I have acquired a set of Australian heads for my engine. I also have a Weiand dual plane manifold and Edelbrock 750CFM Carb. I also have a Holley 600CFM. As you know, the Australian heads have standard (2V) ports and valves. I would very much like to optimize both performance and efficiency without spending a fortune. The most "bang for the buck" idea. Before doing too much, I have some questions.

I intend to port match the heads. I plan to use 1 7/8 headers with 2 1/4 Collectors. I also plan to use roller rockers with 1.7 ratio.

Should I:

1. Use 4V exhaust valves (1.71)?
2. Use 4V Intakes?
3. Use the stock Duraspark or an MSD type ignition?
4. Use a roller cam or dual hydraulic?
5. Polish the exhaust ports?

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Old 09-21-2006, 04:52 PM
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Read the above TECH ARTICLES and they should set you in the right direction.
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Old 09-22-2006, 05:29 AM
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I'd use 4v exhaust valves and 2v intakes - 2.19 is plenty big enough. If you port the exhaust leave the port floor alone and consider a set of 'port tongues' between head and header to raise the port floor.
Most of the stronger clevelands here run at least 8 deg more exhaust duration regardless of cam type.Don't use too much spring or too heavy a pushrod as this seems to be a common error here and only shortens valvetrain life.
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Old 09-23-2006, 01:14 AM
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First, the proper term is 400 rather than 400M.

They are commonly overrated but have enormous potential. How does a 434/400 stroker with 799HP @ 8000 sound? Iron 351C 4V heads and factory, 3.00" main block too.

Obviously, the people who claim they are only for torque don't have the slightest idea what they're talking about.
Who says you lose 250-300 horsepower?

What's your application (street, street/strip or racing) and how much power are you looking for and how much $$ is in your budget?

Aussie 302C heads won't make much past 400HP unless they are heavily modified. Check with http://www.tmeyerinc.com/ for newly available, high performance components for this application. Look for the dyno test of a mild street build where they tested various intakes and carbs.

Port matching the heads can sometimes do more harm than good. 1 7/8 headers are not needed unless you're making at least 500HP.

You want Ford 1.73 ratio roller rockers because 1.7 ratio is likely from a BB Chevy application. They don't have the correct geometry for a Ford head.

Use 460 valves instead of Cleveland 4Vs. They measure 2.09"I/1.65"E and are just about ideal for 2V ports. I wouldn't use a 1.71 dia unless there's too much valve recession.

A Duraspark will work fine after the advance rates are modified. The advance was tuned from the factory for the lowest emissions, not power. A solid, non-roller cam will give the best bang for the buck IMHO.

You don't need to polish the exhaust ports, just smooth them out. Nearly everyone I talked to who tried them said the port tongues didn't make any more peak power.

Last edited by Brian S; 09-23-2006 at 11:21 PM.
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Old 09-23-2006, 01:09 PM
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re:400 Aussie

I used the term 400M just as identification. I get tired of reading articles that say 400 and 3 paragraphs into it I find it is a Chevy or a stroked Windsor or Mopar or something no one ever heard of. I would just like to get some good advice on a healthy street 400. I bought the car new and as I said, I always thought it had great potential. No, it's not the best to make power. Fell in love years ago with the 427 FE. Actually, the one I always thought was interesting was the 406. Just different, I guess. That should give you and idea of what I'm looking for. A little different and great potential. I would like to take a while and get parts together so the cost wouldn't be too much all at once. The 400 HP neighborhood would be just fine considering it's only about 180 now.

From all your advice, it sounds as though the 2V size valves on exhaust (2.06-2.09) is the way to go and 1.71 valves are not necessary or at least won't hurt. I am really more concerned with the exhaust side working as well as reasonably possible. Would you think 1 3/4 exhaust would be right or even go to 1 5/8?
I guess the concern about port matching is to open up the Intakes too much. I would look at the gap and if it involves a wide flange of metal, don't think I would do it. Could you get the exhaust too wide?
How much problem would a solid cam be on the street? I'd like to keep the problems down as much as possible. Don't mind doing a little work (infact, I enjoy it) but I don't want to set the valves every weekend either.
I had thought to use the cam maker's advice on springs and pushrods. I thought the lift should be in the 525-550 range. Does that sound about right? Maybe 270° duration?
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Old 09-24-2006, 01:17 AM
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400 HP at the crank is pretty easy to do. A common mistake people make is to bolt a set of Aussie 302C heads on a standard 400. Stock pistons are too far down in the bore to gain any quench benefits from the closed chamber head. Zero deck pistons, like the ones available from Tim Meyer, are mandatory to get the recommended .035-.045" piston to head clearance.

There's not too much you can do about the exhaust other than standard porting. Larger valves don't increase airflow because the largest restriction is in the port itself, mainly the short turn radius. One fix is to use a split duration cam with about 8 degrees more duration and higher lift on the exhaust lobe to compensate.

Stock 2V valves are 2.04/1.65. 3 reasons why I recommend 460 valves (2.09/1.65) is because they are easily available, they are not made from 2 pieces welded together and they have single groove stems.

I could direct you to a dyno on my forum of a 383/351C stroker that made 523HP with 1-3/4 headers. 1-5/8 is plenty for a 400HP engine if you can find that size for your application. Header pipes larger than necessary have a detrimental effect on low to mid range torque.

Ideally, an intake port should taper all the way to the valve to keep fuel suspended in the airstream. Intakes like the Edelbrock 400 Performer have ports smaller than stock manifolds to increase port velocity. Port matching one of these will actually reverse the tapering effect designed in the manifold and cause fuel droplets to fall out of suspension. Edelbrock specifically states not to port match their intakes but how many people listen? A port mismatch is not necessarily a bad thing and can even have some anti-reversion benefits.

A solid cam doesn't require much maintenance other than checking valve lash every 10K miles but for 400 HP a hydraulic will do just fine and save a few bucks on machine work, screw-in studs, guideplates and hardened pushrods.

A cam like the Lunati Bracket Master II woud be a good choice for a 400 making peak power in the 5200-5500 RPM range. Shoot for a compression around 9.5-10:1.

Check out Tim's site for some ideas about carb and intake selection.The best combo made just under 400 HP.
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