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Cross-fire Ford .......

O

Olf Art

Silent Prop
R. I. P.
I've been thinkin a lot lately about DD car boats. I like the idea a lot because they're lighter than any similar boat with a redrive ....... especially if they're using a heavy old Franklin belt like mine, and they're simple.

Quite a few years ago I worked with a guy who ran a USAC Midget dirt track car, powered with a little engine they called a cross-fire Ford.
Back in '38 and '39 Ford built a little V8-60 ...... a little 60hp flathead V-8 engine. As you can imagine they were quite a bit smaller than the standard flatheads at that time, and a real pretty little piece.
They didn't stay in production for too long because they didn't have much power, and because gas was so cheap that folks weren't very worried about mileage back then.

Anyway, the engine to beat in those days was the 110 Offy, a 110 c.i. Offenhauser 4 cylinder, purpose-built for racing, and they were expensive, so Ed Iskenderian (Isky Racing Cams) ground a cam for the little V8-60 that put two cylinders on the power stroke at the same time. It was an eight cylinder, but it ran like a four.
Just like airboats it takes torque to run on dirt, and when my buddy's little Ford was right it would fly. He ran third one night in a 50 lap feature behind two Offys and ahead of five others.

Why not a cross-fire 350 c.i. small block Chevy ? Or better yet, a cross-fire 500 c.i. Caddy ? An eight cylinder engine, firing on two cylinders at a time ...... the equivalent of a 350 or 500 c.i. water cooled four cylinder ? You want torque ? One of those would have it by the truck load.
 
Something like that would work fine I think, Northwest ....... maybe a modified GM 4 cyl. distributor with a programmable advance curve.

I can hear Thunder scratching his head all the way up here. :)
 
If you had a rotor that fired on both ends, it would solve your ignition for firing two cyls at the same time.
 
that would mean that pairs of cylinders where at TDC at the same time...someone that knows engines would have to chime in here.
 
In an 8 cylinder engine, for every 180deg. of crank rotation, two cylinders are at the top at the same time. It's the cam grind that determines which one of them is on a power cycle and which is on exhaust.
For every revolution, four cylinders are in intake/compression cycle and four are in power/exhaust. Those are the four cycles.
It takes two full revolutions for all eight to fire. With a six cyl. Lycoming or Conny, only three of of those six fire every revolution.

With a 'cross-fire' setup, an eight cylinder engine would fire four times in two revolutions, but two cylinders at a time ....... an eight cylinder running like a bigass four.
I think this would help overcome the fact that DD motors don't get to turn fast enough to make big torque.
It looks to me like one of them would make tons of torque, and at the lower RPM that they need to operate at because of their prop speed limitations.
 
Do you think that a direct drive will out perform a your redrive? Seems to me you would gain alot more performance with the belt drive than you would by losing the weight of the redrive.
 
Sounds interesting , but what do you think it would cost to prototype
a cam ( not owning my own cam company ). Nissan's Z 24 engine
was an eight plug four banger that fired off both ends of the rotor at
the same time. Seems like the ignition problem could be overcome
fairly easy, Now to just convince someone they can sell those cams.
 
I love thinking outside the box so that's why I started this thread in the first place. Thanks to all of you who have contributed.

K-mac, I'm sure Comp Cams in Memphis, TN could grind one if they knew what a man wanted. In this day and age it's not much more complicated than punching in some numbers on a Cad/Cam machine.

Barhopper, the thing that fascinates me about this thing is that a car motor boat could probably be built that would run with gearbox and belt drive boats without all the extra hardware. Simple, lighter, and a lot cheaper. You're only talking about a cam change and a different distributor.

However ...... because I believe that a big inch 'cross-fire' engine could swing a pretty good size prop, the engine would have to have a thrust plate/thrust bearing between the end of the crank and the prop flange.
The crank bearing caps in such a motor probably wouldn't be able to stand the increased push this engine would make all by themselves.

That part would be easy.
 
As far as a distributer you might be able to just make a double ended rotor for the distributer that is there. At low rpm's the coil should have plenty of dwell time to be able to fire both spark plugs. They would fire on both strokes the compression stroke and the exhaust stroke but that wouldnt hurt anything. Harley's did that for years. That would be a fun project.
Tim
 
Tim, I wish I had the space and resources to try and build one. If someone has an old small block laying around it would be a perfect 'mule' to
use just to experiment a little.

Wasted spark is common to a lot of engines ..... a lot of Honda and Kawasaki M/C engines use it too.
You might be able to find a four cylinder cap (industrial?) that would fit a standard Delco distributor, and then just siamese the plug leads off of it. That would double the soak time of the coil and make a hotter spark.
A crank fired ignition would work great for one, but would add a lot of expense.
 
Or as long as we are building a new cam from scratch, cutting the distributor
speed in half shouldn't be to tough, just a new gear ratio.
or even use one of the new motors with no distributor, and you may
only have to manipulate the ECM to get what you want.
 
I like the way you're thinking .... simple and direct. A stock eight cyl. ECM would probably be confused by what we're trying here, but maybe one for a crank fired four might not ?

I like that. :)
 
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