Valve Shape & Seat Angles

Ricardo developed his flathead mod in the early 1920's- by bringing the top of the chamber down to the piston crown, he solved the detonation problems with 65-70 Octane gasoline. This assured the flathead's place in surface transport for the next 30+ years. Aircraft started going OHV in WW 1, by WW II, they had advanced to the point where the German DB 605 engine featured Direct Fuel Injection into the cylinder- without a computer! It was a modified Diesel engine used to power Zeppelins. It could use 87 Octane, which kept the Luftwaffe flying after 1942, when 100 Octane got very scarce in Germany. It got better fuel economy than Allied engines, and could push over into a dive without stalling due to fuel rising out of the carb throat. 60 years later, Detroit is telling us DFI is the Next Big Thing, and will get 50 mpg- as soon as they can computerize it- oh please! Want to "Live in the Past Today"- Detroit's got you covered!

Vergil's link www.eurospares.com/graphics/engine/Vizard/ shows how DV's work can apply to flathead engines. Go to Porting School #8, and start at "Downdraft Angle". Look at pic .0391.jpg - imagine the port as upside down, and you'll begin to see why flatheads don't flow very well. Continue on thru "How to Get the Port Size Optimal" , and look at .0401.jpg discussing round ports. Next, look at the pic entitled "Real World High Efficiency Intake Port"- this is a proven high velocity, high flow port. If I wanted to work on the Ford engine pinch point, this is where I'd start. I'd epoxy up the roof of the short side, and widen out the sides of the port approaching the valveguide-this way, you won't hit water. I'd also epoxy over the valveguide top to make a ramp up to the valve seat. There's a pic in Auto Trader- www.autotraderclassics.com/car-article/Ford%E2%80%99s+Famous+Flathead-75386.xhtml - it's towards the end of the photo section, just after a valve pic and an assembled engine pic.
 
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Gona take awhile to go through this. I did allot of flow bench testing of the flathead and never fund the Holy grail of flow. Maybe I missed something.
 
I was always afraid the epoxy buidup might come loose and cause engine damage on a daily driver, is this a proven way to modify the intake ports (using Epoxy Resins). Here are a couple of early direct fuel injection patents.

Vergil

dirinj-1.jpg



dirinj-2.jpg
 
On an OHV engine the charge can litterally "fall" into the cylinder making it relatively easy to fill. If you take a Ford Flathead intake port, flip it over and place it over the center of a cylinder I'll wager you'd have a pretty decent flow situation.

Think about what is happening in the normal Flathead configuration. The charge does'nt really know the port is upside down. If the source of vacumn was directly above the intake valve getting the charge to flow up is not that big of a deal. But it's not above it, it is beside it and this is my take on what happens. The piston moves down and creates a pressure differential. At low engine speeds and low valve lifts the basic layout works pretty well. The charge moves relatively freely through the port, does not impose too much of a challenge at the valve seat and then exits into the sufficient combustion chamber area.

Now lets say you want to increase valve lift and raise engine speed and compression ratio all in the name of higher performance. Here is where the logs begin to jam. First the suckage through the port is increased and the charge is litterally crammed into the back of the valve pocket, the part nearest to the cylinder. It is then mechanically forced straight upward which is not really where it needs to be obviously. Furthermore a sidevalve engine only exposes about 50% of it's valve curtain area to the container it is trying desperately to fill. Almost all of the intake valve's perimeter is flowing on an OHV. In my humble opinion the ultimate flow/power killer in a Flathead Ford engine is the fact that all of the already limited intake charge flows smack dab into the solid wall namely the cylinder head. To make matters worse, in the name of higher compression we tighten up the combustion chamber making it even more difficult to get decent volumetric efficiency.

I freely admit that what I am about to say is strictly theory on my part. I am but an impoverished working man with little time to prove the science but I will one day . But here goes anyway....... the perfect valve job aside, the real solution in my opinion is to change the relationship of the intake port, valve seat, transfer/combustion chamber and cylinder perimeter and centerline. First and foremost the actual dome of the combustion chamber needs to be as high as is practical. I'm talking like an inch higher! This is the only way you can truely give the engine a shot at good cylinder filling. Next I feel that the edge of the intake valve and the edge of the cylinder should be as close together as you can get them. This is achieved obviously by increasing their diameters. This situation will help make more valve curtain available and more of that same flow area will be aimed towards the center of the combustion dome. Additionally the high combustion dome requires the transfer area to be sloped in a much more favorable direction and shape. It could actually direct the charge way more effectively that the almost horizontal position it is in on a conventional head design. Lastly I too believe that the valve pocket could use some filler in the backside nearest the cyl. The intake port could then really be massaged to flow as close to the center of the combustion dome as possible.

Ok, I painted a rosey picture so let's think about the bad part. Is there really a bad part to what I think would be a better power strategy? Hell yes but it ain't that bad. First it would require pop up pistons and cyl heads to match. Both of these exist right now today. They are somewhat higher in price than conventional parts but since pistons and cyl heads are almost always replaced on a high performance flathead engine build you are talking a difference of hundreds not thousands of dollars. The other possible drawback is that super high dome heads and matching piston are not often used on street engines therefore the body of knowledge as to their driveability on the street is limited. That is what I am most concerned about. That is what I am determined to get around to testing on an engine I can install in my own car for evaluation.

Look the thing is, even I can coax 135- 150 hp out of a Flatty that I build depending on the parts and preparation I use. The best guys in the business that are way smarter than I, seem to hit a 220- 240hp plateau even in killer high end engine builds. I'm sorry there is an obvious limitation in there and i'll bet you a dozen doughnuts that it is right where I think it is. We'll see.....
 
Many OHV engines do not use all the valve curtain area due to port angle- the flow goes out sideways, just like the flathead. I think a lot of people miss that fact and intuitively think this is a major flathead problem.

Ricardo's flathead contribution was to lower the head in the chamber to piston level- this solved detonation problems that plagued the flathead with low octane fuel. Whether today's fuel would be a problem in a high-roof chamber would have to be experimented with. However, popup pistons have problems with flame travel- today the trend is to flattop or dish pistons for efficient combustion.

The primary reason flatheads can't compete with today's OHV is bore/stroke ratio- a square ratio (stroke equal to bore dimension) is more efficient for an internal combustion engine. If you wanted to update the flathead, the quickest way would be to adopt the rotating assembly- crank, rods, pistons- of a modern smallblock, and cast a sidevalve block to fit. You'd want to look carefully at the ports & valves of the Hudson 7X engine, or at the last Packard flathead as a design starting point. You'd want individual ports, and you'd want them optimized for flow, especially in the valve area. The exhaust valve area would need to be designed with efficient cooling in mind (the Dodge had a water distribution tube with openings aimed at the seat).

If the same effort had been put into the flathead that was applied to OHV's after WW II, they'd likely still be around- they're MUCH cheaper to make than OHV's, especially DOHC 4-valves. Emissions wouldn't be any more of a problem, either- tests have shown they'll pass if they're not burning oil. Vergil- Epoxy won't be a problem if you prep the area correctly, and use the right type- JB Weld works well (Intake ports ONLY). Henry- Jack Clifford was getting 290 Hp and just shy of 500 lb/ft Tq out of the Hudson before he died- his motto was 6=8!
 
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You will be able to answer your own questions with the test models you constructed and a flow bench or an Audie "Flow Quik". See some results from flathead Ford flow testing in my books "Blown Flathead" and "335 HP Flathead Ford V-8 Performance Handbook" available from Amazon, Speedway and others. Check www.blownflathead.com or www.roadrunnerengineering.com for more info. Let us all know what you find. We all learn from each other.
 
As Joe said, you will answer all of your questions if you're willing to do the work. As far as HP goes, as far as I know the two most highly developed Ford flathead engines were Flatdogs and the Kloth engine. As far as NA horsepower goes, the crown has to go to the Kloth engine with 280+ HP from 267 Cubic inches.
Epoxy works well in racing applications, but is not a long term (street) solution, and is, in fact, highly susceptible to any alcohol in a fuel. In a race flathead, some make custom guides, then lock them into the block and shape them to their desired contour. I think Pete here has made mention of doing that himself.
BTW, Joe, I like the book(s)
Jim
 
welcome, blownflathead...good to see you here and hopefully you will continue to post and share your knowledge....Mike
 
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