I'm not sure I understand. Gravity & physical orientation should produce no significant difference on on flow in a flathead or OHV port. For Intakes, inertia will compell the charge to follow the long side no matter if it is overhead, sideways or upside down. It really wants to travel in a straight line unless forced otherwise. For Exhausts, I need to do more investigation. I would expect the same, but perhaps there is a "bounce" (reflection) off the long side curve that directs the exhaust flow to the short side of the port?? This is Consistent, although a larger valve will increase the shielding at the back of the chamber this is more than compensated for by the enlarged window at the front. Straightening the port and reducing the underhead 'tulip' will direct the flow through the front opening with the least loss of velocity & momentum enabling more charge to enter in the intake period. Win.Win.Win.
For what it is worth, some photos of a Mercer valve seat and chamber. They are different from a Ford but they still are a flathead (T-Head). They were designed as a racing engine and were very successful and are almost 7:1 CI which was about 3 points higher than everything else at the time. Take a look at the space on the left hand side of the valve in the first photo. That is the clear space they provided so that the valve can breath all around on the back side, the rest of the chamber and cylinder is to the right. Into the threaded area above the chamber is a valve cap the bottom of which is flush with the top of the chamber. There is approx. 3/16 clear space between it and the valve at full opening. The two plugs (one per side) are in this cap directly above the valve. To get an idea of how they are constructed look at the video I posted earlier today.
Thanks Herb, that helps me see that the HD work is applicable to the A/B. As far as the tonguing goes......deserve maybe no........want, sometimes. .
Some more interesting reading and charts from Philip Smiths Competition Engines book explaining changes in CR and fuel. The last chart giving pressures at different CR ratios is interesting. The text states at ignition the pressure raises to 3-4 times the pressure on the chart. So next time you think that a so so valve job, ring seal to cylinder, warped head or questionable head gasket is OK look at these figures. A 6:5 to 1 CR when it fires produces 600 - 800 PSI !!
Hear is what I'm envisioning on combustion chamber mods for the "Winfield" High Comp head. The red shape is the standard shape. The blue lines represent the mods needed to clear the valves. The 1.700" dia is the intake valve. The radius were the roof meets the wall has a 3/16" rad.. The depth of the chamber is @ 5/8" deep. I would use a 1/2" ball end mill to make the mods so that those areas would have a 1/4" rad.
CDO: From everything I have learned, read about and have actually tried I think you are on the right track. I have done this on T Ford HC alum heads and have been more than happy with the results. A little loss in CR is going to be more than made up in power gained by a better charge in the chamber at ignition assuming there is clearance between the valve and head. PS..... I have done this before by putting the head on a rotary table in the mill, but CNC would be quicker. If you think it all out it will work fine.
What would you think about changing the intake valve center point? Maybe moving it toward the cylinder @ .060" - .100" ? I know that it would move the valve stem off center of the lifter, but you could put bigger lifters in to cover the valve stem. It would help straighten out the port too. .
Good idea, the large distance between the valves & cylinder is a waste, its just using up compression. Oh.. and Increase the valve diam. by .200", back to the wall, forget the cut-outs, push the valve into the roof, and straighten the port as much as possible... Now, we are really using 20th not 19th century technology. (in the nicest possible way...oops! NO.. not That way
I intend no serious disrespect to the Mercer. It is a Stunning Machine with leading edge engineering & technology, for it's time. A lot has been learned ( & much forgotton) in the last 100 odd years. However, "Tried & True" 1930's technology can only ever give us 1930's performance. "Not that there's Anything wrong with that"! I'm only suggesting the possibilities of using "things" discovered since the commercial demise of the flathead to continue it's development.
Bill, You can't miss the Nats again this year. We need you out there having fun with us. Weeks, Are you coming down for the Nats this year? .
I believe this is the old "Ed Roy" Miller that could have been bought for $6,000 in the early 1970's. It was thought to have been the car Frank Farmer was killed in. Has the true history been nailed down? It looks great, sure would like to see and hear it run.
The Earl Cooper #2 crashed at INDY in 1925 on lap 127 on the SW turn. He was back in '26 with a FWD MILLER.
CDO...... That is an excellent idea....... Your lifter plan is great also. By not moving the lifter the valve timing is not affected.
T-Head, if your still on-line. I'm still stuck without access to my stuff. Do you have the standard Model A valve diameters handy? Cam specs too? standard or a "tried and true" performance one would be great. I'll try to run some "sims" before bedtime. its 8;30 pm here now. Cheers,
I'm with you 100 % with new technology and use it when ever possible. One thing that we have to keep in mind is that not everyone is building a limited use racing engine where very high compression is OK. Unless you are going to have a new alloy crank made and put a girdle on the bottom if you use a Ford crank w/high compression you are eventually going to have a broken crank. It is not a matter of if, it is a matter of when. Serious racers in the day would put in a new crank after every event because they would sometimes break at the next one. For engines that are not full out it has actually been shown that unshrouding the valves and letting it breath actually ends up with more power even after the minor compression loss. Compression isn't a magic drug in all situations and in a lot of Fords it also leads to overheating, blown head gaskets and starter problems in addition to broken cranks I am trying to show the average person who wants some more power in the end without all the trouble that is going to come from very high compression. The only way to be safe with a Ford and high compression (over say 8:1) is five mains which is out of the reach of many people.
the standard Model A valve diameters are approx 37.7mm diameter, and thats a very quick measurement, taken as I was getting my young girls off to bed hope that helps
No sorry..... I don't have much A speed information here. I have a lot of experience with them but over the years but am more into T Fords.
T-Head, I hear what your saying. I understand the strength limitations of bangers. I certainly wouldn't want any-one to damage an engine by using my proposals without awareness of the weaknesses. I guess it sounds like I could be promoting the High Comp race motor route, but thats not really my style or aim. My projects are all of the Budget type, based on maximising results through thinking smarter not $$$$. My emphasis on 'lost compression' is to have allowance available to maximise our transfer and chamber shapes to produce a stronger, smoother and more efficient combustion. This should be no harder on components than 'normal operation' yet produce significant improvements in Torque. Improvements in these areas will enable an engine to run cooler, not hotter, for example. Some of the ideas should be of interest to racers too. I am refining them for my Chrysler L-6 project. Thanks Stovebolt, for the valve diams. Any-one else out there with some cam specs?
If you can find a way to come up with smoothness and less heat that would be a good benefit as most HC flatheads have very harsh combustion which I believe is the root of the breakage problems along with torsional vibration troubles. If you are building a six you probably already know this but you need to be even more careful with torsional vibration as a straight sixes have big issues with it and they break cranks even more regularly than a four.
I'll try to be carefull T-Head, I hate breaking things (except, perhaps, speed limits and the "Unwritten Laws"). Thanks again Stovebolt.
I agree 100% with what TR-Head and 88D are saying. Someone building a car for B-ville is going to have their own opinions and probably going to ignore, (or possibly scoff at) what is posted here. The average lead foot will benefit more from this thread. One thing that might be interesting to try- and possible without investing lots of money in slightly different camshafts- is this Come up with a way to keep the tappets from rotating (like what is needed with roller tappets. Now make tappets with the cam contact area AT AN ANGLE to the stem of the lifter. This give you the ability to play with different lobe center degrees, by having the angle face one way for intake, the other way for exhaust. Closing this angle, with an open exhaust especially, will give more HP, and an engine that "comes on the cam" quicker. I have made tappets from D2 tool steel, with the cam face chilled by setting on a large steel heat sink, and then drawing just the stems back softer with a torch while just the head is in water. (D2 is air-hardening) Certainly not modern heat treating- more like '20's shade tree stuff, but it has worked so far (the hardening- never tried the angle---CDO- sound like something that you might like to try?) Herb
Keep the technical info coming fellas. This is a great learning tool and should not be scoffed at regardless of one's knowledge. The H-D KR/KRT heads have me intrigued so i went searching and found a racers manual with some good drawings and specifications. www.scribd.com/doc/19365642/Harley-Davidson-KR-XLR-Racer-Manual
I once worked in a screw machine shop that made lifter conversion kits to convert hydraulics to solids, When the chevy V8 started to gain in popularity we worked on developing a lifter that was compatible with all cam materials. The most commonly used steel for mass production was at that time known as leaded screw stock now I believe it is 12L15. It was found that if the rockwell was above 65 (file hard was the term used then) that the lifter would work well. 12L15 is not a direct heat treating material it was case hardened. The firm we made them for, Thomas Magnesium later Val Vee Engineering, made up the term "Specially Chilled Steel" This was considered quite funny to those in the trade. Dempsey Wilson ( Clay Smith Cams) did the development as he ran them in some of their boat engines. I remember the boss, AK Ferris, saying that the engine blew at 7 grand but the lifters looked good. There were no engineers involved just a couple of old time hot rodders. The bottom radius was something like 27" laid out with a string and a pencil on a manila folder transfered to a piece of shim stock then which was then used as a pattern to dress a grinding wheel which was then ground on the cutoff tool and polished by hand, Many years later I ran diesel injector cam followers out of 86L20 which is a far better material as the internal structure retains a medium strength where as 12L15 has a soft center kinda like an egg. I have considered making new large foot print lifters out of 86L20 but not sure the demand would be there. When I now need a hardened part such as a rocker shaft I use O1 or 41L40 bar ends from my son. I heat treat the parts and then I "soak" them in a lead bath for 1 hour at 800 degrees to draw the part back to around 45 to 50 rockwell. Just some more trivia for you from my cave!
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