Cylinder head design

[Kahuna]

I was just reading the thread about blown head gasket problems on some after market cylinder heads. An interesting discussion to me.
I currently do not own a Model A, but have had several in the past with stock heads, milled heads, Winfield, Cyclone, and an overhead conversion.
My question:
Why aren't the combustion chamber designs of the after-market flat heads more closely linked to the late model (46-53) Ford V8 flathead designs? Is it because the compression ratio would be too high? Is there a worry about the babbit in the rods and mains? Or is it something that I haven't thought of? Just wondering.
Seems that a Model A/B would be real happy with a compression ratio of about 8:1.
Maybe I'm just whistlin Dixie
Any thoughts
Thanks
Jim

[1930artdeco]

8.1 would blow the babbit right out after any length of time.

Mike

[Bruce Lancaster]

Vertical valves and huge difference in distance valve to cylinder are a differing factor here...implicit adaptation of Ricardo design, followed by lawsuit, came in V8 times...flat piston V8 heads, '32-36, are very different from the classic '37-up type and much closer to Model A/B practice...but valve placement in the V8 was substantially different than Model A in several ways.
B made about one horse per 4 cubes..V8 by 1934 made one per 2.5, huge difference in expectations. Fenderless '32-33 Fords running as stock cars in the Elgin races could hit 100MPH. How stock is an interesting question with answer hidden to us, but there was a huge real world difference in top end. Interestingly, one limit on top end power in '32-33 Fords was the whippy forged crank (sound familiar??) and those cars actually grew higher top speeds when they got replacement '34 cast cranks of same diameter!

[Jim Huseby]

I had the exact same question as you about the combustion chamber shape and after a year or two of investigation of FH chamber designs and performance on various engines, made a very simple observation. By just looking at old Motors Manuals, it's easy to calculate the HP/cu. in. for every engine listed. The latest of the Dodge and Plymouth FH's, around 1959, made the most specific HP of any FH's listed. I had a couple of those Mopars in the shop, so it was easy to copy that. Also, the junior dragsters that start out with a 5HP B&S engine are developing over 50 HP (10 times the stock engine! That would theoretically be 350-400 HP from a Model A!) and its head design was similar to the Mopar. I had an aftermarket aluminum high performance A head that had plenty of thickness for radically changing the chamber shape and then milling it back down to 7 to 1 and cc'ing. I gave lots of room and flow shape around the valves and transfer area. The shape of the flame front and its relationship to the changing shape and size of the chamber with changing crank angle was a phenomenon that I couldn't adequately model. My theory was to get as much of the explosion blown onto as much of the piston head area as possible at TDC while, at the same time, encouraging efficient cylinder filling on the intake "stroke". This, of course had to be considered with the diameter, length, constrictions, etc. of the intake system, along with a consideration for turbulence, which the A is reputed to require a lot of (I don't really know, or how to test for it). During this research and experimentation, I realized there were several varying philosophies or approaches for specific benefits that had been tried over the lifetime of the FH engine, and theories and experiments are still advancing.
On an RK engine with inserts, full pressure, Carillo rods, 1 3/4" int. valves, hot touring cam, S 94 carb, header, electronic Mallory, etc., my experimental head makes lots of whacking HP with no indication of a HP drop-off above 3000+ RPM. Now that's not a very scientific answer for you, as it hasn't been dyno'd or raced against another similar car ('30 coupe with fenders, bumpers, Zephyr gears, 3.78, etc.). There are many influencing factors that I played with and tried to balance with each other or make mutually effective. There are many factors I can't rearrange, such as the-mentioned valve angle and proximity to the cylinder, and I'm sure many that I don't understand. The Mallory as set up has too much total advance, so the engine will be too retarded at low RPM if timed for fast running, or KNOCK at above 2500 with much throttle if timed for low speed running. I'm thinking that a stock curved B distributor will have about the right amount of total advance, even though I'm aware of much of the data already out there for a set-up similar to this. BTW, it hasn't blown the Felpro dark gray head gasket with about 1500 miles, but its over-due a re-torque.

[Crazydaddyo]

Show us a picture of your new combustion chamber please.

.

[BRENT in 10-uh-C]

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Originally Posted by 1930artdeco

8.1 would blow the babbit right out after any length of time.

Mike

Mike, respectfully that really isn't a true statement based on my experiences. To substantiate this, think of diesel engines manufactured in the 30's & 40's that used babbitt, ....their longetivity was substantial with much higher compression ratios. The proper type and installation of babbitt will withstand everything we would subject it to in a Model A 'banger' engine.

Kahuna, I think the biggest thing you see with higher than an 8:1 CR is loss of volumetric efficiency, --or loading the charge into the cylinder. The other thing that kinda affects some of this is the stock siamesed intake ports where it is difficult to get #2 and #3 a full load of fuel/air. There are several good combustion chamber designs, ...and the one that I like is the one that 'Pop' Evans made that is very similar to a late flathead design. One final thought to remember is the RPM differences between a flathead V-8 and the A/B flathead 4 cylinder.

[just plain bill]

Originally Posted by BRENT in 10-uh-C

Mike, respectfully that really isn't a true statement based on my experiences. To substantiate this, think of diesel engines manufactured in the 30's & 40's that used babbitt, ....their longetivity was substantial with much higher compression ratios. The proper type and installation of babbitt will withstand everything we would subject it to in a Model A 'banger' engine.

Kahuna, I think the biggest thing you see with higher than an 8:1 CR is loss of volumetric efficiency, --or loading the charge into the cylinder. The other thing that kinda affects some of this is the stock siamesed intake ports where it is difficult to get #2 and #3 a full load of fuel/air. There are several good combustion chamber designs, ...and the one that I like is the one that 'Pop' Evans made that is very similar to a late flathead design. One final thought to remember is the RPM differences between a flathead V-8 and the A/B flathead 4 cylinder.

I have had good success with the "Crows Foot" combustion chamber as used by Winfield and others.
I would hesitate to give a limiting number to the compression ratio as there always seems to be some one that has had success with a higher compression ratio although I'm running close to 7.7 to 1 at this time.

[Crazydaddyo]

Here is a configuration that I have been thinking of:



The dashed line would be the standard chamber shape for a H/C head. The solid line outside that would be the modification.
I was also figuring that the chamber roof would be higher over the intake valve and the spark plug would be located closer to the intake valve.

.

[Crazydaddyo]

Here is what a JR. Dragster head looks like. Keep in mind they do run them on Alcohol.

[BRENT in 10-uh-C]

Originally Posted by Crazydaddyo

Here is what a JR. Dragster head looks like. Keep in mind they do run them on Alcohol.

You mean "some" JR dragster heads look like that...

.

[Jim Huseby]

Crazydaddio- I didn't take pics, but will when the head has to come off, I hope a long time away. Compared to the jr. dragster head shown, it has a little more roundness behind the ex valve so that when the ex gasses slam against the wall behind the valve, they will be smoothly routed back toward the opening. The transfer area is taller, allowing as much flow there, especially intake, as possible while keeping the C/R up. Instead of the chamber essentially abruptly ending 1/4 of the way over the piston (3/4 of the top of the piston is not exposed to the flame front at TDC in the jr. dragster chamber shown, which appears to have at least 10 to 1 C/R), I ground away the dam or ridge and sloped the chamber toward the far side of the piston top, thinking that would get pressure on the top of the piston sooner and smoother than waiting for it to travel down far enough for the expanding gasses to reach it. We do understand that with the little chamber shown, there will be lots of turbulence and that the flat area above the piston is a squish area, and that that configuration makes lots of HP in the jr. dragster and many, if not most high performance FH heads. I am not a scientist or expert in this area, but I am insanely curious, and being blessed with ADHD, did not control the urge to get out the die grinder and risk ruining a good Thomas head. I would like to hear lots more on this subject. JH

[Jim Huseby]

Hello Brent- Yeah, SOME jr. dragster look like that. The one I copied looked more like I described, but with milled ribs standing in the transfer area, I presume to take up some space without impeding the flow too much. I did not use the rib idea, and arrived at 7.1 to 1 with .080" over. Please tell us more about the performance figures of that jr. dragster as the real proof here is in the pudding and not my theories. I think it is worth the embarrasment and loss of a blown up engine, if necessary, to experiment with going faster. Would you venture to tell us how you will use this knowledge on your next secret weapon? We all know you're thinking up something. JH

[Bruce Lancaster]

The Jr. Dragster head is similar to all '37-53 Flathead heads...
The purpose of the tight area above the piston, as you note, is the Ricardo principal, essentially, the same effect exploited in most SBC heads. That are in these designs is kept as tight as possible, numbers like .040, for turbulence...the mix on compression is forced out and over toward the transition and valve area, allowing homognous mixture with lots of turbulence. One noticable effect is a simultaneous need for LESS spark advance (often taken as an indicator of combustion efficiency) combined with lowered tendency to knock...a flathead or sbc will both run higher compression with less tendency to spark knock if this area is tight, and will lose response and knock more if this area is too far from head.
A difference is that the flathead piston top and the chamber above have matching shallow domes.
Flathead valves are canted several degrees toward the cylinder (as are the valves of the circa 1932 British Ford 4 cylinder and the Ford USA N series 4 of 1939), which directs the probably circa 30 degree flow off of the seat more towards piston area. The rise in the transfer area matches this flow in stock heads.

[just plain bill]

I have noticed that the Winfield heads that I have use a different radius for the intake valve and the exhaust valve in the combustion chamber wall behind the valves. I think the JR dragster head that CDO posted looks similar to the standard Winfield pattern as to the transition to the flat area over the piston which maybe a bit shorter, Of course that just might be my old eyes.

[MrTube]

OK now I'm confused.

If Ethanol produces less power than gasoline why would you use it on a high performance engine?

[Kahuna]

The junior dragster head presented by Crazydaddio is but one of many head chamber designs and is very close to a stock Ford flathead in design. However, that design is not the type used by the successful racer. It is much more refined and used a lot in tractor pulling stuff (riding lawn mower type pulling).
Valve angles, to me, mean little, as both the Briggs and the Kohler engines do not have offset valve gear. I'm not familiar with the output of the Briggs, but the Kohler engines do, in fact, produce more than 50 HP. 50 HP is needed to be competitive. More is needed to win.
As Brent mentioned RPM, let's talk about that a little. I see no reason that a Model A/B shouldn't be able to run to 5K, properly built. Also, the Briggs/Kohler stuff is run upwards of 9K. Big difference.
My original question was really about the aftermarket. With what is known as far as "late" head design, why do the Brumfield's/Synder's just use the older designs when clearly the later stuff would be better?
Jim

[d.j. moordigian]

I asked Larry Brumfield twice about spark plug location and/or angle here on the
Barn. I thought it was a good topic for his improved combustion chamber head, but
no answer. I think plug location is a horsepower maker.
Dudley

[Crazydaddyo]

Originally Posted by d.j. moordigian

I think plug location is a horsepower maker.
Dudley

Winfield thought so too.

.

[Jim Brierley]

The late Harley racing flatheads had an interesting chamber, and ran very well. In the 30's, all this was still being developed. Things don't happen overnight.

[gilitos]

Put a little ethanol in one palm and a little gasoline in the other: the ethanol makes your hand colder as it evaporates. It has a higher heat of evaporation, meaning that it cools its surroundings more as it evaporates. In an engine, this means that you can run much higher compression ratios without detonation when running ethanol (methanol, too), which means more efficient combustion (i.e. more HP per unit of fuel). Air/fuel ratio has to be adjusted to get this potential power, though.

[BRENT in 10-uh-C]

Originally Posted by gilitos

Put a little ethanol in one palm and a little gasoline in the other: the ethanol makes your hand colder as it evaporates. It has a higher heat of evaporation, meaning that it cools its surroundings more as it evaporates. In an engine, this means that you can run much higher compression ratios without detonation when running ethanol (methanol, too), which means more efficient combustion (i.e. more HP per unit of fuel). Air/fuel ratio has to be adjusted to get this potential power, though.

Ummm, are you certain this is true? I was thinking that it had more to do with BTU's, ...which ethenol does not have.

.

[Jim Huseby]

I can see in the shape of the Crazydaddio chamber pic some other characteristics that, to my thinking, would make it very effective. The radius around the perimeter of the valve area and transfer area would make for smooth and effiecent flow to and from the valves with minimal turbulence and ricocheting around of the gasses, as turbulence during intake and exh phases would be detrimental to cylinder filling and"'chamber emptying". The large radius at the end of the transfer area would direct the intake charge about as efficiently down into the cylinder as possible, but during compression would make terrific beneficial turbulence , as already stated. My confusion has to do with getting the explosion onto the top of the piston, and at tdc, most of the top of the piston is not exposed. But I think I am starting to understand what really happens. If the expanding "ball of flame" takes say .0025 of a second to reach full pressure from the moment of spark, by that time the downward stroke has begun, the "pressure ball" can reach the whole top surface of the piston, and that will occur at the most advantageous crank angle (depending on RPM and ign timing) to use the pressure during its availability. I guess most of you already knew that, or am I correct in my thinking? Again, BMEP, dyno testing and track performance (which includes flexibility and longevity) are the real proof of concept. I have a Lion Speed single plug head and dual plug head and though I don't understand their chamber technology, their dyno results are impressive for power and RPM range. That is not to denigrate by comparison anyone else's head, as there are some impressive and consistent reports on many FH's and all are interesting. I hope more of you will relinquish your FH chamber design secrets or ideas on this thread so we can go faster, impress ourselves and maybe blow up another engine or two.

[Crazydaddyo]

Originally Posted by Jim Huseby

I hope more of you will relinquish your FH chamber design secrets or ideas on this thread so we can go faster, impress ourselves and maybe blow up another engine or two.

Careful, talk of speed and performance modifications on this site may lead to severe tongue lashings, banishment to far away lands, and/or burning at the stake. The quest for speed is considered "witchcraft" on here sometimes.

I only showed the B.S. head as an example of how different it is then the typical A/B HC head. Brent should show us what a "real" JR Dragster head looks like.

Lets not get off topic with the debate over how alcohol is used in racing.


There are schools of thought that believe the squish area between the top of the piston and the head is beneficial to the combustion process. The thought is that the more piston area that comes as close as possible to the head, the better the heat transfer and the cooler the combustion. Without cool oil squirting onto the bottom of the piston, there is not efficient way to cool the piston. This area will also create detonation too. So the size, clearance, and shape of the squish is important. It is this reason that if you are using a "crow's foot" style squish you want the spark plug near the intake valve which is the coolest part of the chamber. The squish will help flame propagation.

.

[Bruce Lancaster]

I was privy to a limited range of selected bits of secrets from the late great Flatdog, builder of probably the most powerful (12.9 in 3,000 pound '34) street driven flathead on the planet. Remember, canted valves and closer chamber, so not necessarily transferable to bangers...
One thing was that flow at back of valves was minimal...best approach was minor clearance behind valve, at least .030 above valve to allow the slight flow. Almost all serious flow was right out the cylinder side, across the back of the valve, and shape of the BOTTOM of the pocket was critical to encouraging this.
He also said that flow bench showed that most flow was on the intake side of chamber because...startling observation, confirmed by other flowbench wizards...the EXHAUST flow mostly followed that side!! I suspect this was a big factor in his work on chamber roof. And I have seen elderly circle track engines with a block relief only on that side...
Flatdog was a major presence in the flathead world, and regularly conversed by phone with various Bonneville types, all people with some sort of flow bench, some with dynos.
They would very guardedly mention tiny fragments of theri secrets to each other, and try to gauge if the other guy had observed anything similar. High tech spy world...I think if I had ever walked into the garage at the wrong time and caught a glimpse of his total chamber design, he would have had to kill me.
Low tech secrets: He started his flow work with a humungous shop vac, tossing kitty litter into the airstream! As things got more sophisticated, he learned from Elmo Rodge how to forn clear plastic shell copies of his chambers so he could put a transparent roof over the flow.

[just plain bill]

my practical comment on the Winfield "Crows Foot" design, no dyno figures, no theory.

[gilitos]

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Originally Posted by BRENT in 10-uh-C

Ummm, are you certain this is true? I was thinking that it had more to do with BTU's, ...which ethenol does not have.

.

...meaning that for a given fuel, higher compression gives you more power per milliliter of that fuel. And because of the cooling effect of alcohol, much higher compression is possible without detonation.

[Crazydaddyo]

Here are a couple of "old " banger HC chambers:

Weiand (7.6:1)



Late Winfield (7:1)



Cyclone (8.25:1)




Thomas



.

.

[Rex_A_Lott]

Thanks for fixing the pics CDO...hate to see this one die, interesting to me as I am about to purchase a new head.
Still hoping Brent will show us the JR dragster head.

[Crazydaddyo]

Originally Posted by Jim Brierley

The late Harley racing flatheads had an interesting chamber, and ran very well. In the 30's, all this was still being developed. Things don't happen overnight.

Jim,
Here are some pictures of the Harley KR set up:

[Rex_A_Lott]

Nice pics of the HD block, got any of the head?

[Flathead]

Barney Navarro made V8 heads that used some of these HD ideas. One of his last projects I think.

[Crazydaddyo]

Originally Posted by Rex_A_Lott

Nice pics of the HD block, got any of the head?

This is the best I've got:

[just plain bill]

Mike hart had a chamber that looked like he working along the lines of the HD design. I have had 2 of the cast iron Winfield "Crows Foot" heads and both have had added clearance for larger valves. When I saw the first one I thought that a previous owner had modified that area but then the second one had the same exact cuts. The area between Valve chambers is .250 or less and requires a "B" gasket. Awhile back some one informed another poster that the "A" gasket worked on Winfield's. Looking at the photo of the Cyclone it might get by with an "A" but I'm sure the Wieand would require a "B" gasket. I had to use a "B" gasket on my repop " Crows foot" Although the chambers are no where as big as the original cast Iron. I once met a old time tracer that told me they (he?) always ran 1 7/8" intakes and the original "Crows Foot" by Winfield will
' clear that size. Once read somewhere that winfield was forced to drop the "Crows Foot" design because off a Ricardo patent infringement. Can't find the reference now.

[Rex_A_Lott]

Thanks for all the pics....interesting looking at all the different ideas.