Flathead valves and flow??

Hey gang I recently attended a local truck and tractor pull. It has been about 20 years since I went to my last one.

Everything there was cool but I was most interested in the"Garden Tractor" pullers because I happen to have a cherry vintage Wheel Horse which is a prized possession of mine.

My Wheel Horse is powered by a "K" series Kohler single cylinder flathead engine. These little engines are things of beauty and when stock mimic the smoothness and deep baritone sounds that our lovely Ford Flatheads exude.

Why do I mention this seemingly waaay off topic subject? Well it's because we Ford V8'ers could do well to take a look under the bonnets of these little puller garden tractors.

First it sounds like they turn north of 7000 rpm. (I think)

They are based on the bigger bore 14 and 16 horsepower block which I think have about a 3 3/8" bore.

The intake port on a stock Kohler is adequate in size but lacks the shape they need so that is addressed.

They run a billet head with a flat top piston and some sort of block relief.

They have an impossibility small base circle diameter camshaft just like a Ford V8 in stock form.

They run a long intake runner with some kind of motorcycle carb on the end.

By now y'all might be thinking "who cares" and that's a fair question because this is a Ford V8 forum. Well I care because these little flatheads turn out about 45-55 horsepower!

I think that is incredible for a small antique one lunger. If one could duplicate that kind of performance in a Ford V8 wouldn't that add up to a 400+ horsepower engine?

Now I realize that's pie in the sky but those guys are doing it and the principles between those little Kohlers and our Ford V8's are much the same.

Food for thought and submitted for your enjoyment.

https://youtu.be/GvPbtUOfQ54
 
JWL, If you noticed, I never mentioned "max flow" I'm trying to make flow improvements. keep the port velocity high and use components that will work efficiently within the constraints of the flathead. I have a couple 59a blocks I'm planning to use for a build. I'm really going to do some research to build a big cube engine that works well on the street. I found some plans online to build a flow bench and a calibration plate to give me CFM data. one of the 59a blocks is cracked with factory relief so I would like to use that as a flow bench mule. what I would like to start with is some valve and seat work to determine what works... is my understanding that once this is determined it should remain pretty static as far as angles and undercuts?? Or will I be hindered by the stock ports before the flow improvements on a stock size valve can be realized fully? I was thinking of putting in a plastic valve seat that I can quickly and easily swap out and make changes to. possibly cut the head off a valve and do the same there... use plexyglass to create a quick and easy swappable valve. In my thinking Valve work on a flathead is kind of a no brainer... you have to buy new valves, you have to do a valve job... why not determine the best flowing combination before you pick them out. I'm sure different chamber shapes will work slightly differently with different valve configurations?? say a head with a higher transfer port might work better with a 45 degree seat than a lower transfer area when compared to a 30 or 37 degree seat or when a relief is cut...

next I would try to move on to porting... this I would need to have some guidance on as there are so many variables that having a starting point would be a HUGE time saver

thoughts??
 
Henry Floored said:
Hey gang I recently attended a local truck and tractor pull. It has been about 20 years since I went to my last one.

Everything there was cool but I was most interested in the"Garden Tractor" pullers because I happen to have a cherry vintage Wheel Horse which is a prized possession of mine.

My Wheel Horse is powered by a "K" series Kohler single cylinder flathead engine. These little engines are things of beauty and when stock mimic the smoothness and deep baritone sounds that our lovely Ford Flatheads exude.

Why do I mention this seemingly waaay off topic subject? Well it's because we Ford V8'ers could do well to take a look under the bonnets of these little puller garden tractors.

First it sounds like they turn north of 7000 rpm. (I think)

They are based on the bigger bore 14 and 16 horsepower block which I think have about a 3 3/8" bore.

The intake port on a stock Kohler is adequate in size but lacks the shape they need so that is addressed.

They run a billet head with a flat top piston and some sort of block relief.

They have an impossibility small base circle diameter camshaft just like a Ford V8 in stock form.

They run a long intake runner with some kind of motorcycle carb on the end.

By now y'all might be thinking "who cares" and that's a fair question because this is a Ford V8 forum. Well I care because these little flatheads turn out about 45-55 horsepower!

I think that is incredible for a small antique one lunger. If one could duplicate that kind of performance in a Ford V8 wouldn't that add up to a 400+ horsepower engine?

Now I realize that's pie in the sky but those guys are doing it and the principles between those little Kohlers and our Ford V8's are much the same.

Food for thought and submitted for your enjoyment.

https://youtu.be/GvPbtUOfQ54
Click to expand...

Thanks. I also love all type of small engines. It is amazing what these guys can do. I'd be curious to hear how much they spend on these one lungers to put out that much H.P. I bet the number would be surprisingly high.
 
revkev6 said:
JWL, If you noticed, I never mentioned "max flow" I'm trying to make flow improvements. keep the port velocity high and use components that will work efficiently within the constraints of the flathead. I have a couple 59a blocks I'm planning to use for a build. I'm really going to do some research to build a big cube engine that works well on the street. I found some plans online to build a flow bench and a calibration plate to give me CFM data. one of the 59a blocks is cracked with factory relief so I would like to use that as a flow bench mule. what I would like to start with is some valve and seat work to determine what works... is my understanding that once this is determined it should remain pretty static as far as angles and undercuts?? Or will I be hindered by the stock ports before the flow improvements on a stock size valve can be realized fully? I was thinking of putting in a plastic valve seat that I can quickly and easily swap out and make changes to. possibly cut the head off a valve and do the same there... use plexyglass to create a quick and easy swappable valve. In my thinking Valve work on a flathead is kind of a no brainer... you have to buy new valves, you have to do a valve job... why not determine the best flowing combination before you pick them out. I'm sure different chamber shapes will work slightly differently with different valve configurations?? say a head with a higher transfer port might work better with a 45 degree seat than a lower transfer area when compared to a 30 or 37 degree seat or when a relief is cut...

next I would try to move on to porting... this I would need to have some guidance on as there are so many variables that having a starting point would be a HUGE time saver

thoughts??
Click to expand...


Kevin, where abouts are you in the world. I'm in west central Florida. If we happen to be neighbors I'd do whatever I could to help you, which honestly and coincidentally would help me too. 😉

Just a FYI. There is a guy in this forum who is in the west coast, I believe his name is Pete. He has built some big inch Flattys. Like in the 320" range.

He has stated on here that he revs them pretty high which I assume means north of 6000.

Keep in mind that the '48 and earlier blocks have valve locations that are, I believe, .090" closer to the edge of the stock bore which is the right direction for breathing in my opinion.

I have an 8BA block at home that is bored to 3 7/16". Believe me the valve seat to cylinder bore distance is pretty on that block. Imagine if you could find a 59A block that could take that large bore.

That's half the battle I think. Maybe more importantly in a Flathead Ford we are asking the flow to make two abrupt nearly 90 degree turns before it can fill the cylinder. Think about that and what can be done to overcome some or all of that.
 
That's half the battle I think. Maybe more importantly in a Flathead Ford we are asking the flow to make two abrupt nearly 90 degree turns before it can fill the cylinder. Think about that and what can be done to overcome some or all of that.[/QUOTE]

Slapping on an OHV conversion is what can be done to fix those two pesky 90 degree bends.


Sorry, I couldn't resist
 
Last edited:
Tim Ayers said:
That's half the battle I think. Maybe more importantly in a Flathead Ford we are asking the flow to make two abrupt nearly 90 degree turns before it can fill the cylinder. Think about that and what can be done to overcome some or all of that.
Click to expand...

Slapping on an OHV conversion is what can be done to fit those pesky 90 degree bends.


Sorry, I couldn't resist[/QUOTE]

Actually Tim you're on to something. Let's think about the flow path on an OHV. In the latest carbureted and central fuel injected OHV V8's the intake manifold was squished way down into the valley to allow for hood clearance.

This is a big reason why those last of the breed engines were lazy pigs. It wasn't until Ford did the SEFI 5.0 V8 that things started to wake up. Next time you have a chance look at the intake runners on even the lowliest 5.0 SEFI Ford. They actually align very nicely with the intake ports in the cylinder heads don't they?

On our Flattys what's going on? Really the exact opposite isn't it? The fuel and airflow source is up way to high. In any L- head you'd want the intake manifold to enter the ports in the block at a very low position.

This isn't a practical idea some would say and most would rather be able to bolt a conventional intake manifold on the block anyway. I get it, BUT!

Now how could we accomplish a better flow situation? Hmmmm
 
Henry Floored said:
Keep in mind that the '48 and earlier blocks have valve locations that are, I believe, .090" closer to the edge of the stock bore which is the right direction for breathing in my opinion.

I have an 8BA block at home that is bored to 3 7/16". Believe me the valve seat to cylinder bore distance is pretty on that block. Imagine if you could find a 59A block that could take that large bore.
Click to expand...

The 59A blocks have the same valve geometry as the 8BA blocks. It's the pre-WWII blocks that have the valves closer to the bores.

Andy
 
awelker said:
The 59A blocks have the same valve geometry as the 8BA blocks. It's the pre-WWII blocks that have the valves closer to the bores.

Andy
Click to expand...

Thank you my bad. I guess my 1941 Mercury block with the early valve geometry and bigger bore is a good starting point for a hot rod engine.

Maybe you know but I was under the impression that Ford moved the valves away to lessen the propensity for cracking in those areas?

Am I on track or totally mistaken?
 
Henry Floored said:
Kevin, where abouts are you in the world. I'm in west central Florida. If we happen to be neighbors I'd do whatever I could to help you, which honestly and coincidentally would help me too. 😉

Just a FYI. There is a guy in this forum who is in the west coast, I believe his name is Pete. He has built some big inch Flattys. Like in the 320" range.

He has stated on here that he revs them pretty high which I assume means north of 6000.

Keep in mind that the '48 and earlier blocks have valve locations that are, I believe, .090" closer to the edge of the stock bore which is the right direction for breathing in my opinion.

I have an 8BA block at home that is bored to 3 7/16". Believe me the valve seat to cylinder bore distance is pretty on that block. Imagine if you could find a 59A block that could take that large bore.

That's half the battle I think. Maybe more importantly in a Flathead Ford we are asking the flow to make two abrupt nearly 90 degree turns before it can fill the cylinder. Think about that and what can be done to overcome some or all of that.
Click to expand...

I'm out of western massachusetts. about as far from florida and california as I can get! not too far from Ron though (wink wink).

as for engine size I'm not looking to go THAT big! it really depends on how it sonic tests but I would like at least 3 5/16 bore maybe up to 3 3/8's if possible with the 4.250 inch crank. 304 would be nice.
 
Just to put a cherry on top of this bloviating of mine I'll add this....

There are many fellas that will say (and rightly so I might add) that this or that won't do much good on a Flatty. A single change like exhaust headers or porting won't be worth the effort etc. In some ways that's right especially since you may not feel a "seat of the pants" difference in a low rpm street engine.

The consensus seems to be that tight piston to head clearance and the best ignition system you can afford are the dollars most well spent.

I wholeheartedly agree with that but I must add that porting changes and even cam and carburation changes are hampered by a he aforementioned road block.

Figure that out and watch your expectations of Henry's venerable V8 rise.
 
Henry Floored said:
Slapping on an OHV conversion is what can be done to fit those pesky 90 degree bends.


Sorry, I couldn't resist
Click to expand...

Actually Tim you're on to something. Let's think about the flow path on an OHV. In the latest carbureted and central fuel injected OHV V8's the intake manifold was squished way down into the valley to allow for hood clearance.

This is a big reason why those last of the breed engines were lazy pigs. It wasn't until Ford did the SEFI 5.0 V8 that things started to wake up. Next time you have a chance look at the intake runners on even the lowliest 5.0 SEFI Ford. They actually align very nicely with the intake ports in the cylinder heads don't they?

On our Flattys what's going on? Really the exact opposite isn't it? The fuel and airflow source is up way to high. In any L- head you'd want the intake manifold to enter the ports in the block at a very low position.

This isn't a practical idea some would say and most would rather be able to bolt a conventional intake manifold on the block anyway. I get it, BUT!

Now how could we accomplish a better flow situation? Hmmmm[/QUOTE]

I think that was the premise of the Ardun heads with some trade offs of course. I'm not well versed on Arduns and would defer to guys like Ronnie the Roadster on this topic.

Since the hemi-head was a proven winner in the pre- and post- WWI European engines, it seemed natural to turn a poor breather like our flatheads into a better one.

Engines like the Bugatti, Renault, Miller (and the later Offy's), and Alfa Romeo are genius in the simplicity of their valve trains and their intake and exhaust paths.

Fuel comes in very efficiently and exits very efficiently all with relatively light weight valve train since it all sits directly over the combustion chamber. Also, since the valves are canted, this allows for the use of a high dome piston to get a fairly high compression ratio to help boost power as well. Add a supercharger like Miller or a turbo like Offy and you are making some serious H.P. out of a smaller c.i. engine.

Cast all of this out of aluminum and you have a light weight, powerful package. There are other things like Miller's and Offy's use of caged ball bearings for the cranks and the combination of ideal bore & stroke, permit them to spin at crazy high RPM's.

Arduns use the hemi design or a modified hemi design(I think), but are limited to the cam in block design. I think C/T Auto made a few sets of DOHC heads for our flatheads. I'd love to hear one of these engines running.

Certainly a lot to think about when designing OHV conversions.
 
I built three 304ci engines. Three different cams , but otherwise nearly the same, big ports, big valves , big cams.
They all perform very good.
But i really think a 304ci engine with little or no port work, stock size valves , 74cc edelbrock heads , or EAB heads and isky1007b or L-100 cam , would give the same fun or maybe even more !!

High compression means high octane gas, big cam mean high rpms ....

You loose more at the bottom rpms than you gain at the top rpms.

Ah and all engine where in 32 roadsters , and had the same induction(3x48)
So i can compare a bit
 
HotRodmicky said:
I built three 304ci engines. Three different cams , but otherwise nearly the same, big ports, big valves , big cams.
They all perform very good.
But i really think a 304ci engine with little or no port work, stock size valves , 74cc edelbrock heads , or EAB heads and isky1007b or L-100 cam , would give the same fun or maybe even more !!

High compression means high octane gas, big cam mean high rpms ....

You loose more at the bottom rpms than you gain at the top rpms.

Ah and all engine where in 32 roadsters , and had the same induction(3x48)
So i can compare a bit
Click to expand...


HRM:

If I remember from your posts, you've used the 404-A and the 425 Eliminator cams.

So what you are saying, you've gotten good results with the 1007b and L-100's which have approx. .250" less lift and less duration than those cams?
 
Henry Floored said:
Thank you my bad. I guess my 1941 Mercury block with the early valve geometry and bigger bore is a good starting point for a hot rod engine.

Maybe you know but I was under the impression that Ford moved the valves away to lessen the propensity for cracking in those areas?

Am I on track or totally mistaken?
Click to expand...


I'd say you are right on track. On the 39-41 Mercury blocks the valve eyebrow cut is just that it intersects the stock 3.1875 bore on the drivers side. This creates a sharp corner which is more prone to heat stress and crack.
 
HotRodmicky said:
I built three 304ci engines. Three different cams , but otherwise nearly the same, big ports, big valves , big cams.
They all perform very good.
But i really think a 304ci engine with little or no port work, stock size valves , 74cc edelbrock heads , or EAB heads and isky1007b or L-100 cam , would give the same fun or maybe even more !!

High compression means high octane gas, big cam mean high rpms ....

You loose more at the bottom rpms than you gain at the top rpms.

Ah and all engine where in 32 roadsters , and had the same induction(3x48)
So i can compare a bit
Click to expand...

what cams have you run?? what components did you use to get the 304 cubes??
 
This is a picture of a 42 Merc block - with 1.72 intake valves (and new larger hard seats) - and 1.6" exhausts. If it is a street engine and you still want to run a hard seat, this is about the biggest you can go. I use a 1.72 Manley SBC Chevy intake Pro-Flow valve that they use in some super-stock heads from the 50's. Nice valve to start with (though I mess with the undersides a bit more).

This block has extensive porting and relief work - and I'm doing a bit different relief work than 'normal' - just an experiment that mimics some of what the top-end Harley KR reliefs were doing. It is running a very large duration roller cam, with .420 lift.

DeckComplete copy.jpg

IntakeValveAssembly-Complete copy.jpg

DeckPicture-AllDone copy.jpg
 
Bored&Stroked said:
This is a picture of a 42 Merc block - with 1.72 intake valves (and new larger hard seats) - and 1.6" exhausts. If it is a street engine and you still want to run a hard seat, this is about the biggest you can go. I use a 1.72 Manley SBC Chevy intake Pro-Flow valve that they use in some super-stock heads from the 50's. Nice valve to start with (though I mess with the undersides a bit more).

This block has extensive porting and relief work - and I'm doing a bit different relief work than 'normal' - just an experiment that mimics some of what the top-end Harley KR reliefs were doing. It is running a very large duration roller cam, with .420 lift.

View attachment 304791

View attachment 304792

View attachment 304793
Click to expand...


B & S you do beautiful work! Wow that is some very well thought out stuff and it looks so consistent from port to port. I know that represents hours and hours of work especially in cast iron!

Do you have flow numbers on this type of port? How much have you been able to do with the short side radius? I can't tell because I'm looking at these pics with my phone but is that relief the same depth for intake and exhaust with a baffle that favors the intake charge?

Using a long duration roller cam kinda sounds like you are building a race engine. Is this a land speed engine? Sorry about all the questions but your excellent work has me giddy like a child. Lol! How does a max effort Flathead Ford compare in terms of airflow and power to the FlatCad project you were involved in a couple years ago?

Anyways that's all the pestering I'm gonna do for now. Hats off to you man!
 
Bored&Stroked said:
This is a picture of a 42 Merc block - with 1.72 intake valves (and new larger hard seats) - and 1.6" exhausts. If it is a street engine and you still want to run a hard seat, this is about the biggest you can go. I use a 1.72 Manley SBC Chevy intake Pro-Flow valve that they use in some super-stock heads from the 50's. Nice valve to start with (though I mess with the undersides a bit more).

This block has extensive porting and relief work - and I'm doing a bit different relief work than 'normal' - just an experiment that mimics some of what the top-end Harley KR reliefs were doing. It is running a very large duration roller cam, with .420 lift.

View attachment 304791

View attachment 304792

View attachment 304793
Click to expand...

Dale:

Hard to tell from the picture, but do you use those O-rings on all the guides?

Thanks,

Tim
 
Dale, your build thread on that motor is something that I drool over every few months. sadly I have had some inappropriate dreams about it lol.

now that you have that beast on the road how happy are you with the KR cam?? which grinds do you have?? E or F in the car now and an H on the shelf??
 
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