I just wanted to add this illustration of the earlier type of combustion chamber that was replaced by the turbulent style head Ricardo discussed in my earlier post. This is the chamber he was discussing when he mentioned overcoming defects and the explanation of it.
WEEKS46. Man I'm glad someone from here bought that, If you would please post what you find in it, that is one cool motor.
On the old flathead V-8's the valves were not parallel to the cylinder bores, the side of the valve head farthest from the cylinder was at deck height, the side of the valve facing the cylinder was sunk below the deck about 3/16". This formed sort of a dam in the way of the flow from the valve. "Relieving" removed this area of the deck, giving a smooth path for the gasses. Model A and B valves are parallel to the bore, so there is no "dam", and no need to releave. A B block is thin in the deck area stock, and it would be a sure way to start some cracks around the valves, which occur all too frequently with the stock setup. Herb Kephart
Thanks for the Kudos, James. We're running Gas Modified Roadster. And yes... those are Alston Clevises... for a swing out bar. I just called them up and ordered TWO kits! Hope to see you out there some time... it really IS as good as they say. Sam
I was literally a day late on this one..............keep the build post updated. this thing is too cool
http://www.jalopyjournal.com/forum/attachment.php?attachmentid=976206&d=1273878111 My deepest respect for Dr Ricardo and his work. My observation, from the above drawing, is that the improved performance and reduced detonation from the above design is due to the reduced and more even flame travel from what approximates a hemispherical combustion chamber. The squish area over the piston is significant too. From the drawing it can be seen that the ability of an intake charge to "go straight up from the valve" is severely impeded by the proximity of the valve to the chamber wall for at least 1/2 of the circumference of the valve. The easiest path to the low pressure area created by the falling piston is sideways out of the valve. Chrysler family 6 cyl L-head engines (used into the 60's) have offset intake ports which naturally create a swirl in the charge. If correctly developed this can greatly assist the flow into the chamber through the intake opening, below the valve head. This allows the chamber to be closed down to max valve lift, increasing compression and taking advantage of high octane fuels. A key element to performance from a flat head engine is the transfer flow across the boundary between the valve/combustion chamber and the cylinder. Gasses must pass through this zone 4 times for each power cycle under varing states of temperature & pressure. This is a greater limiting factor than just the intake flow. Compression ratio and the transfer flow area will tend to compromise each other.My preference is always the flow over a high static compression ratio. Concentrate on filling the cylinder fully and a high compression ratio will not be necessary or even desirable. NOTE: I offer no dyno charts or proof of my rambling notions.
Thanks for sending in your thoughts and the information on the Chryslers 6-cylinder. This is exactly what I am interested in finding out, what other types of flathead designs are out there that are an advancement from Ricaro's and Harley-Davidsons findings. Can you share any photos or drawings of these Chrysler ports and heads?
This driver is only identifed as Dode Withrow. The car appears to be a T Ford based racing car. The location looks like a mile horse track? Can anyone add more?
Go here to read the 1931 edition of Harry Ricardo's book. www.scribd.com/doc/22469332/The-High-Speed-Internal-Combustion-Engine-Ricardo-1931 T-Head, have you heard of the 'Riccy chip'? It is an insert that bolts to the combustion chamber of an F-Head allowing the engine to breath better as well as raising the CR close to the 6:1 figure you mentioned earlier. The two cam Harley Davidson engines later adopted this design that has always been attributed to Ricardo.
Kurtis...... No I have never heard of a "Riccy Chip"..... is that an Aussie name or term for it? Do you have a picture of one? I like the Ricardo link, I wonder if there are any on Google Books? Thanks T-H
No it's not an Aussie term. I asked because i thought if you have Ricardo's earlier book maybe there is some reference to this. As far as i know only the 61inch HD engines had this insert and i don't know how many used them. As i mentioned the later two cam racing engines used this same design feature that are referred to as Chicago heads or 'Pineapple' heads. I have never seen a photo but from what little info i have it is said to have promoted a better squish area within the chamber. I have always wondered whether the Ricardo designed head on the single cylinder Indian motor had this feature as HD later copied his design onto their side valve engine as that is where the term 'Riccy chip' originates.
I'm not sure if you are familiar with this car which I believe has run 103 at the drags. Anyway, I was parked next to them a few years back at the Antique Nationals and had a conversation with one of the brothers. He told me that they had done quite lot of experimenting with combustion chamber shape. He said his brother would get an idea and they would weld and recut. He didn't pass on any secrets but he did say they ran stock cranks. The car has very sophisticated conversions such as the ignition. I'm not sure if I would want to run a drilled "T" front axle.
Yes it´s mine but its not banger powered, Chevy straight six in that one. Pic 2 is my coupe with banger power.
I did a little more digging in my library tonight and looked into one of my most helpful books. A friend gave me this book years ago and it has been very helpful in my shop where I rebuild mostly pre 1920 racing and high performance engines. It was written by P.M. Heldt who was considered and expert for years and he consulted with many other engineers who helped with the book. It basically tells you how to engineer an engine from scratch and I have found it a lifesaver when I have made things like new blocks, crankcases, bearings and many engine parts here in the shop. I included what he has to say about flathead chambers and in 1951 he mentions that Ricardos theories were still valid and still used on most flatheads. Included is a drawing which shows the valves much farther from the chamber wall so they can breath upward which is how this design is intended to work. This gives a much better flow than breathing sideways as I understand from studying this and reading about airflow around valves. I will include this in the next post. I hope you find all of this as interesting as I do, because if you study it you will understand how your flathead works and what to do to make it do what you want. Let me know if you are interested in this kind of tech as I can post more in the future but don't want to unless you folks enjoy it. So post you opinion or PM me.
This is why I read the banger thread every day. Please keep posting the tech and old photos !!!!!!!!!!! .
Thanks for all the info... Your shop looks like a cool place to play...I mean to WORK Do you have info on intake runner length?
T Head Some time ago I read Ricardo's writings on designing smoother combustion type chamber for flatheads, and as I recall his goal was to try to get a (relatively) gradual rise in the pressure buildup in the cylinder, while still maintaining the anti-knock advantages of squish. One thing to bear in mind, is how cars were driven when he first began that research. First, and second gears were only used to get the car rolling to the point where the engine would pull smoothly in high- even if the engine speed at that point was much less than 1000 RPM. Roughness under these conditions was something that a manufacturer wanted to avoid at all costs. I agree that the roughness of a high compression may very well be a contributory cause of T crank breakage (as is the practice of retarding the spark to start, and once the engine is running advancing the spark to the maximum - and leaving it there)--but a T engine is one where the stock transmission makes lugging the engine under certain conditions almost a certainty. My thinking is that if you want to take a '20's engine and significantly raise the compression, you should be driving it more like a modern engine (within the limits of the rods, crank,etc) and not lugging it. Just my 3 cents (inflation is coming) The Riccy chip was a backyard go-fast item for the 61 and 74 CID F head Harleys '13-'29. It was a lump of bronze that was fastened into the top of the combustion chamber over the bore, and held there by a single bolt through a existing hole in the center of the head, (the head and cylinder were a one piece casting). I think that they did very little to improve the flow, but could raise the compression to almost any desired amount, depending on the size of the lump. I think they were more legend than success, as having a large lump of uncooled metal, held by one bolt must have promoted detonation and the single bolt was a disaster waiting to break and drop the lump--with obvious results. Herb Kephart
http://www.jalopyjournal.com/jal_attachments/1/0/4/2/2/7/976716.thumb?d=1273965827 The extra clearance in Heldt's chamber might allow some additional flow during the initial valve lift. It might be even better without the square corners which reduce chamber volume and provide pockets of uncombusted charge. Blowing smoke in steady flow conditions and at speeds and pressures that produce visible images is poor model of the actual events. As intake charge flowing through the seat area approaches it's maximum speed (sometimes close to supersonic) the restriction at the back of the chamber and over the top of the valve (flat in this instance) is likely to dramatically slow or even stall the gas flow. This could then produce a pressure shock wave back into the port further disturbing the flow. Plenty of valve clearance and a nice curved chamber roof will undoubtedly allow a pretty looking (smoke) flow but we're also back to 4:1 compression. Note: I have no computer modelling to support my position.
T-Head please keep posting your tech info it is very informative maybe it goes a long way to explain the success of a hemi head[overhead be that it is]. By the way i have found that Rajo intake same as the one on page 8 choped 50 ford posted [i have trouble posting pictures] if thats what you are after
Breathing sideways, under the valve head might not be as disasterous as it first appears. Consider the high performance Two-Stroke engine which does all it breathing sideways through rounded rectangular ports,yet manages to produce the most HP/cc of any naturally aspirated engine. Many Flat head engines have very large valves on relation to their bore diam. It would take a Hemi chamber (Chrysler, Jag etc) with the valves at around 90 degrees to fit these in the bore. Valves at 90 degrees are restricted on one side also. Here's a pic of a mid 50's Chrysler head And this is the "modern" Edgy alloy head. There is a HAMB thread on a 238ci plymouth engine with one of these heads at 9.75:1 cr. it was dynoed at one point at 175hp.@5000. This was progressing toward a 200hp. target. Chrysler 6's have a much stronger bottom end than the average banger. Days & days of reading on Mopar L-head engines in old posts on the hamb. Look for stuff by Moparsled & Hudsonator.
Thanks.... Do you want intake length or total intake tract length? Let me know I might have some info in my library. Also what type of use?
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