The Crossflow Chronicles

Adapting an Aussie Crossflow head to the US 200

Aluminum Crossflow head on a US 200 block

The 200 is a great block with a very poor flowing cylinder head. Seven main bearings, a nodular crank, a decent oiling system, and nice forged rods - there is a lot of potential there.

With the US style integral log head, a 200 ci six will grudgingly yield 200hp, if you go to great lengths to adapt big carburetion, do a lot of porting, run lots of compression, and pay close attention to quench, cam and other details. You end up with a powerful engine but not one that you'd want to drive to work or school everyday.

With an Aussie 2V style head, you've got a bolt on performance option. You have also licked the non-removeable intake problem and power levels increase greatly, but those low flowing exhaust ports are still there. And 2V heads are getting older and scarcer. The law of supply and demand is driving up the prices on the 2V, almost to the point that a good head might cost more than the rest of the engine.

That might lead you to look at a Crossflow engine. The Aussie Crossflow engine is a big leap over the US design, but in order to use the aluminum Aussie head, you had to use the Aussie block with it's unique bearings, seals, gaskets, timing set, and tin. Then to use that Aussie block in a US car you also had to adapt an Aussie bellhousing and cobble up a clutch linkage for our LHD layout or find a rare C4 bell and flexplate. That's a lot of hardware to find and ship halfway around the world and a good bit of effort to fit it to our US cars.

But with a bit of ingenuity, we've developed a relatively easy method to bolt a better flowing aluminum head to a US block. This technique will work for either the US 200 or 250 engines and can be done without precision machining or welding.

With a Crossflow head, the airflow numbers jump significantly. The high velocity intake and exhaust ports and high swirl chambers work very well to deliver a lot of power. Some have found that the ports are perhaps marginal for the 250 cube engine they were originally designed for, but a close look shows that even in stock form they are optimally sized for a 200. Also, since they are aluminum, the head weighs 40lbs less than the old integral log head.

We estimate that our "mild" 200 with 9.0:1 CR and a stock cam will put out 155 - 165 hp. Hotter versions will easily exceed 200 hp. A massively ported, naturally aspirated full race version with 11.0:1 CR, a 300 degree cam, and triple 45DCOE side draft Webers could reach 399 hp @ 7500 rpm, according to the simulations. While that may be optimistic, this engine could conceivably reach BMW M3 levels of performance.

Modifications

The required modifications fall into two categories: Block Mods and Head Mods.

You must do both for the head to fit.

Assembly

A couple of additional pieces are needed to bolt this all together:

• Aussie Crossflow cam - US cams will not work since the port arrangement
  is different. The stock EFI cam is a good choice for a mild engine. Crow Cams
  makes a variety of hotter cams, as do other Aussie cam vendors.
• Buick 3.8 liter V6 pushrods for earlier non-roller cam engine - 12 ea .
  (just tell the counter guy it's for a 1984 Buick Regal).
• Ford V8 or 3.8 V6 lifters - Get 12 lifters for a 289/302/3.8 non-roller engine.
• Aussie Crossflow rocker assembly - 1.73:1 ratio Ford 351C or Ford 429/460
  pedestal type rockers may be substituted. Boss 302 or Big Block Chevy
  rockers
  may be used if the rocker pedestals are machined for 7/16" studs and 351C
  guideplates or a Crane 351C/429/460 guideplate adapter for 5/16" pushrods
  is used.
• Aussie intake and exhaust manifold or headers. Headers for a US 200 will
  NOT fit.
  The stock exhaust manifold is nicely made and flows well. The stock 2bbl
  intake will accept a Holley/Weber DGV style carb. 2bbl and 4bbl manifolds
  are available from Redline and Cain in Australia. Contact Ford Six Performance
  Parts for header options.
• Crossflow headbolts - Boss 302 headbolts or studs may be substituted.
  7/16" -14 x 4.25" long Grade 8 bolts and washers can also be used.
• Stock or Duraspark I distributor - The Duraspark II distributor will not fit a 200
  Crossflow. The intake manifold interferes with the DII distributor cap.
• Crab-style Distributor cap - this is something you have to make.
  Details Coming Soon!

Please!

Do not e-mail us asking for a "kit", parts, complete engines, or for prices. This is strictly a DIY project. Prices will vary according to whatever arrangement you make to obtain your own components from Australia.

If you would like to build one yourself, you can inquire about Aussie parts and post your questions at www.fordsix.com/forum. Thanks!