Quote:
Originally Posted by Henry Floored
Tim the lost compression is gained back by using a very hi dome piston which tightly fills the raised combustion chamber.
Yes the Flathead Ford certainly has some compromises compared to later engines. For example the small diameter camshaft combined with equally small diameter lifters. Makes agressive cam grinds a little tough. Combine that with the lack of a rocker arm to multiply lift, that's a big compromise. But yet the lack of rocker arms is one of the reasons why Flatheads are so simple and endearing.
But compare the Flathead Ford to many other antique engines and quickly we see that our beloved Flatty's have performance written all over them. They are compact and light. They have good fuel distribution with all the intake ports grouped near the carb. They have a good oiling system with insert bearings on most of them.
As far as 95% of guys being happy with a standard built 276" I would love to say you're right, but unfortunately what I really see is a lot of beautiful early Ford bastardized with all sorts of goofy GM and Mopar powerplants. Do I think that a Flathead Ford could ever compete toe to toe with a scrub 350? Heck no, but for me I'd like to suprise a couple of those guys with what a Flathead Ford can do. I guess I'd like more than just a strong cruiser. I'd like a stoplight bandit, one that could at least give a lazy crate 350 a run for it's money. That might be fantasy, but the idea of it is really cool to me.
As far as a pop up engine goes, I don't think it's all that exotic. There are only two components that deviate from an average build and that's the pistons themselves and the cyl heads that compliment them. I'm certain those items could double the cost of my theoretical engine but I'm determined to try it at least once. This engine could be built in any bore/stroke configuration including stock 221 or 239. It's just the pistons and heads and the machine work to make it happen.
Ron has shown us an excellent cross section of a Flathead Ford intake port. It definately could use a better short turn radius and a little more cross section. But if you look at the flow path it seems Ford designed the bottom of the port as a ramp directing about 80% of the incoming flow right under the far edge of the intake valve and straight up into the transfer area. In my humble opinion the transfer area is the single biggest cork in the process. As the piston races down the cyl you'd think that it would just suck the charge right down with it, but actually I believe that in fact a column of air moving that fast just can't get turned that abruptly. It bangs into the cyl head, piles up and get's bounced around till finally heading down to fill the cyl. By moving the combustion chamber up and increasing it's volume that same column of air now has a space to flow to. Backpressure in that area is relieved and we should see a corresponding increase in volumetric efficiency.
A Flathead Ford has an inherant advantage over almost any ohv engine in that it does not need a fancy combustion chamber shape to swirl or rotate the intake charge when the piston comes up to suspend the fuel droplets. The Flathead's piston pounds the mixture from over the top of the cylinder to the valve chamber and when the mixture is lit it is pretty well mixed by all that natural movement. This gives a pretty efficient combustion process. Another advantage is the ability of a Flathead to swallow huge crankshaft strokes. A scrub 350 has less than a 3 1/2" stroke while a standard Ford has 3 3/4" and a Merc a full 4". Then there are all the stroker combos that can be had at a decent price like 4 1/8", 4 1/4" even 4 1/2" are all in the realm of real possibility. They are cost effective too. Those big levers can provide a lot of grunt. That's another Flathead advantage.
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I believe that haveing no rocker arms is a big advantage as you have
a very light valve train and can use single springs.
Then you can run wild cam profiles
People say you have to watch lifter bores with a Isky 404A , but who
has seen oval ones in real?
I`ll try a 404A in a 284ci next year and then we will see!