Flathead - Has anyone "split" the center exhaust port?

IMHO, you would be better off using a wedge splitter in the center port. I have had good luck with the. Will not help the looks but would serve a purpose.
 
JSeery said:
What it looks like with the center port split, LOL.
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I guess splitting isn't all that it is cracked up to be. I guess I'll stick with one hole.
 

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One other thing you might want to consider is the effect that four pipes might have on the flathead sound. In the firing order, cylinders 2 & 1 fire one right after the other while all other cylinders have a non-adjacent cylinder firing so there could be a slightly different sound pattern coming out the pipes. You could lose the unique flathead sound.
 

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jimTN said:
IMHO, you would be better off using a wedge splitter in the center port. I have had good luck with them. Will not help the looks but would serve a purpose.
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Interesting. I would have thought that shoving a chunk of cast iron into an already restricted exhaust passage would restrict it even more.
 
The wedge splits exhaust from the two center cylinders and directs it out the port. Some say it is not help. I have had good experience with a cooler running engine.
 
So, all these years later I got it running. It was actually last Sept/Oct that I first got it running, but I was focused on breaking in the cam, so I kept the rpm’s at around 2,200. For those that thought the classic flathead sound might be affected, the answer is I doubt it, but you can judge for yourself. Let me know what you think.

https://youtube.com/shorts/LrnudR-jcok?si=HMfGt4Znd0KR5fr5

https://youtube.com/shorts/1Rod3fA5C7M?si=SnEnmcNxmnlwVTw5

https://youtube.com/shorts/XQLD3GsMNgM?si=eyoleq7zfmci0tTQ

https://youtube.com/shorts/xcIFp9dTnBE?si=bHl8QYGMhG5HIj9p
 
Originally the center ports of a flathead took turns firing between the two cylinders, it was only when you put a high-performance cam in that the center ports started to interference with each other. One of the dry lake's racers set the record in 1948 when he came up with the idea to split the center port. I was told this by good friend Jack Calori before he passed away, he had set the record in 1947. For years now they have sold you a chunk of steel you shove up the exhaust port that's held in place by a set screw underneath the cylinder head stud that runs into that port. It crowds out the port quite a bit, but it divides the port and keeps the exhaust from passing over into the adjacent cylinder. I used to over John Bradley's house who at one time was the fastest flathead on the planet, he suggested to me to use a piece of 1/8" steel plate that fit tight in the center port and then tack weld in place so it wouldn't be as restrictive but that was for an all-out drag motor and I don't think it was designed too last very long. I went ahead and used the thick clumsy one that's held in place by the set screw. For his drags motors he had exhaust pipes coming out the front and back corners of the block. There was nothing about one of his motors that resembled a flathead anymore. My dad had bought a '32 roadster drag car in the mid 50s that wasn't running to good. He took it John Bradley and when he got done with it ran really well. I was really lucky to get to meet these guys while they were still around.
 
I have heard of that divider and there seemed to be debate as to whether it helped or not, but it’s first hand accounts like yours that are the most intriguing. When I first posted this I recall that even “ol Ron” (may he RIP) was intrigued about what might happen, and the reason I searched for this thread was because someone had asked me yesterday if I thought it might help with the scavaging of the exh gases. I honestly don’t know the answer and as you mentioned it seemed to work for all out drag motors.
The Siamese exh port on the passenger side is shared by cylinders 2 & 3 and on the driver’s side by cylinders 6 & 7. Looking at the firing order 1-5-4-8-6.3-7-2. Based on this firing order, cylinders 2-3 are 180 degrees apart as are cylinders 6-7. One the surface, one wouldn’t except any advantage of splitting the Siamese exh ports as those cylinders don’t share successive firing sequences but reality and gas flow are much more complicated than that. We I find kind of interesting is that in this vid, if you listen closely, you can hear a slight “popping” noise in the background. To me, this might actually be the moment of ignition of the compressed air/fuel mixture and the associated flex tubing and 4” collector are acting as some sort of amplifying chamber or maybe just unburnt fuel igniting in the exhaust. I did check the plugs, and there were all covered in soot, so it was running rich. I will say this though, that I thought the 4” diameter might be too large and as such might negatively affect the engine performance, however while breaking in the cam last year at around 2,200 rpm, the exh gases exiting the tip of the collector were sufficient to blow over the the grass in my lawn next to the tip.

https://youtube.com/shorts/LrnudR-jcok?si=zORavkxp83ZZUdSd
 
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I know nothing about splitting the center port, but loved the videos. It's nice to see work from a guy that has a vision and is rolling up his sleves and creating a living and breathing mechanical marvel. Can't wait to see this chassis/engine combo transform into a 'vintage ' race car. What Fun!
 
I own the Mitchell Muffler Pickup, a Model A Pickup built during the War. Originally, he built it as a flathead V8 but then he changed it to an Olds in 1950 which it has now. I believe it was the third hot rod anywhere to have an overhead V8 in it. It took second place at the first grand national roadster show in 1950 with the flathead V8 in its division, and it won the Pasadena Reliability Run with the flathead Ford. That Olds engine also only has three exhaust ports just like a flathead Ford. I'm pretty sure Olds copied Fords exhaust layout except they cast a thick divider down the middle of the center exhaust port so the two cylinders couldn't contaminate each other. It has two-carbs and a cam and it's scary fast for a 1950 hot rod. It doesn't way very much. It's still the same except somebody shortened the 1925 Model T bed that they only made for tow-months. I have been looking for 30-years for a good '25 bed, they are different than the rest of them. This was never a pickup; it started life as a roadster car and was modified into a pickup. You can't even hardly tell except that it has a deeper cab, I could use another '25 Model "T" pickup bed if somebody knows where one is at. The funny thing is there is one in a front yard a 1/4 mile away that is in perfect condition. The only '25 bed I have ever seen and it's practically in my own backyard and the guy will not sell it for any price.
 

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Flathead Fever said:
I own the Mitchell Muffler Pickup, a Model A Pickup built during the War. Originally, he built it as a flathead V8 but then he changed it to an Olds in 1950 which it has now. I believe it was the third hot rod anywhere to have an overhead V8 in it. It took second place at the first grand national roadster show in 1950 with the flathead V8 in its division, and it won the Pasadena Reliability Run with the flathead Ford. That Olds engine also only has three exhaust ports to just like a flathead Ford. I'm pretty sure Olds copied Fords exhaust layout except they cast a thick divider down the middle of the center exhaust port so the two cylinders couldn't contaminate each other. It's got two-carbs and a cam and it's scary fast for a 1950 hot rod. It doesn't way very much. It's still the same except somebody shortened the 1925 Model T bed that they only made for tow-months. I have been looking for 30-years for a good '25 bed, they are different than the rest of them. This was never a pickup; it started life as a roadster car and was modified into a pickup. I could use another '25 Model "T" pickup bed if somebody knows where one is at. It's out in the garage collecting dust since I had my stroke.
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588340
 
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