But the head suffers some design shortcomings that are difficult to address. We've seriously considered radical machine work to allow the addition of a decent fabricated intake, EFI, lots of combustion chamber reshaping, but it would really not ultimately yield much more power. The basic head design is very limited and you can only do so much.
The problem lies in the design of the cylinder head. The combustion chamber is a simple wedge design with little swirl or turbulence built in. The quench area is small. The spark plug location is too near the cylinder wall which increases the distance the flame front has to travel. The valves are shrouded by the chamber walls, but the small cylinder bore only allows so much additional valve relief to be added. The 1.75" intake valve and 1.38" exhaust valves can be enlarged, but then cylinder wall shrouding really becomes a factor.
On the bottom end, however, are seven very solidly webbed main bearings. The cam is well supported and the oil pump/distributor drive is near the front of the cam to reduce cam twisting from those loads. The oiling system is simple and direct, with a generous oil gallery providing the mains and the cam plenty of volume even with just the stock pump. The block is a thinwall casting and is very lightweight for its displacement. The 250 water pump is generously sized and provides a great deal of coolant flow for an engine of this size.
What we have is a very good block in need of a much better head!
Ford of Australia did develop a better head with a detachable 2bbl manifold in the mid seventies. they are a direct bolt on for the "integral manifold" head, but they are rare and expensive, even in Australia. The ultimate solution for us was to skip ahead to the next generation of Australian six cylinder engines: The Alloy Crossflow!
Produced in great numbers since the mid 70's, it is
relatively inexpensive and has plenty of aftermarket support (albeit in
Australia). This is a viable option to produce over 200 streetable
horsepower! For more info on this engine, photos, our plans, and
our progress, go to the Crossflow
Chronicles!
1973 Maverick 250 C9DE block, .030 overbore, decked .040
Stock Cast Crank, turned .10/.10
255 V8 Pistons, 9.8-1 CR, 1.585" compression height
Hastings cast iron rings
Comp Cams 260 hydraulic camshaft, springs, lifters
Adjustable rockers on shimmed stands
D8BE 200 cylinder head, mild porting
Clifford headers with 2" dual exhaust, Dynomax Turbo mufflers
14" Hayden electric fan
'91 Lincoln AOD transmission
1 bbl Motorcraft (Carter YF) carb from 78 Granada