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Old 12-16-2010, 05:58 AM   #1
chuck stevens
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Default exhaust port dividers

Does anybody have an opinion on center exhaust port dividers. I have heard they take up valuable space and don't help performance that much.
Walt and Ron your advise is very honored, thanks Chuck.
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Old 12-16-2010, 06:14 AM   #2
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Default Re: exhaust port dividers

Have used them with and without.......work best when useing a cam on a street engine......
Tony Baron told me years ago that they did a high speed test with them in and out..... made know noticeable change..............
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Old 12-16-2010, 08:44 AM   #3
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Default Re: exhaust port dividers

A waste of time for 98% of our flatheads. Unless you are building an all out FH I would say forget it and even then I don't think you would notice any improvement. JMO
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Old 12-16-2010, 09:09 AM   #4
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Default Re: exhaust port dividers

I put them in an 8BA I am currently running. I don't have any quantitative analysis, but they just make sense to me. I was trying to address the cooling issue more than performance. That is, keeping the hot exhaust gasses from sharing the common area.

Maybe it is just me, but the dividers from Speedway do not mount where the instructions lead you to believe that they mount. That is, they look like they are held in place by the center stud. That places them too low in the passage and would act as a mega restriction. It took a lot of grinding and shaping, but I placed the dividers well up in the cavity directly between the valves. I drilled a hole into that cavity via the water passage exposed with the head off. I tapped the divider and used a stainless steel button head bolt sealed with JB Weld to hold it in place, see picture. Admittedly, probably a lot of work for not much gain, but what the heck.

You have to use kind of a Zen approach when you do this like I did. Feeling around with them in place, it does feel like a nice "coke bottle" shaped area and I always heard that is a good design for evacuating gasses.
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Old 12-16-2010, 10:01 AM   #5
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Default Re: exhaust port dividers

I like your method of holding the divider in place. While running the stock car I had one come loose, made a hell of a racket and was a pain in the a-- to remove. The divider is un-necessary when using a mild cam. long exhaust cam timing is what causes the contamination of the intake charge. One valve is open high pressure is bled off, nowe before it closes the ex valve next to it opens under high pressure, allowing exhaust gas it enter the open valves cylinder. This is only a breaf moment and a few degrees of crank rotation. The next time you have an opertunity to see your engine with the heads off check this out.
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Old 12-16-2010, 10:35 AM   #6
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Default Re: exhaust port dividers

36Tbird. You've figgered out the way to do it.
I should comment further: When I saw 36Tbirds approach, I started to do some testing, using the blow end of a vacuum cleaner, with and without those dividers in place. It's a bit difficult to explain here, but there is no question that (installed Lou's way) they WORK. I can't imagine that they wouldn't help even with a stock cam, as there is just no possibility of exhaust contamination with those dividers in place. Also, his installation leaves no possibility of them ever coming loose, or turning in the exhaust tract to create a problem. JMO. As 36Tbird mentioned, I think the instructions included with the dividers are incorrect.
Jim

Last edited by Kahuna; 12-16-2010 at 10:53 AM. Reason: added info
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Old 12-16-2010, 11:29 AM   #7
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Default Re: exhaust port dividers

Years ago I went to visit John Bradley “ Mr Flathead’ who at one time had the world’s fastest flathead dragster. He told me he did not like the bulky cast dividers and preferred to tack weld in an 1/8” steel plate divider. I had a pattern laying there that he let guys trace so they could make their own. I’m pretty sure on a street engine that the tack welds would eventually break, but on a race engine that has had the water jackets filled solid and exhaust ports coming out places that never had them I don’t think a broken tack weld was a big concern to John.

Another guy I interviewed was Pete Henderson. Pete was good friends with Randy Shinn who held the SCTA Roadster record back in 1947 and 1948. Pete credited Randy Shinn as being the first guy who came up with the idea of using port dividers. Pete seemed to think the dividers made a difference on an all out dry lakes car.

There is probably a benefit to using exhaust port dividers with a big high duration cam. On a mild street engine I’m not sure they make much difference. I went ahead and installed the cast dividers in my 59A engine that has a Winfield SU1A cam, just so I can say they are in there, it’s a nostalgia thing. I ground down the dividers to remove a little bit of their bulk, then I made them pretty with a Roloc disc.

I own Dave Mitchell’s Olds powered pickup from the fifties. I had to recreate the original 1951 left header which was made from a ’35-36 Ford Driveshaft with inch thick flanges, it took me a month of my spare time to build it. These early Olds V8 engines only use three exhaust ports, the center two cylinders share one port just like a flathead does. While I had the header off I noticed that the Olds head has a factory built-in port divider (see photo) I think the GM engineers stole this speed secret from the flathead Ford guys.
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Old 12-16-2010, 04:28 PM   #8
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Default Re: exhaust port dividers

I have a set on a 59AB 60 over by 4 engine with an old track cam.
They are mounted under the stud with allen screws. That engine runs very cool.
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Old 12-16-2010, 04:50 PM   #9
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Default Re: exhaust port dividers

Tennessean Jim, so what are you say'in? Are those cast dividers you have in that engine held in place with allen screws? Where are the allen screws that hold them in place? Finally, what is a "59AB 60 over by 4 engine"? Inquiring minds want to know!
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Old 12-16-2010, 05:52 PM   #10
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Default Re: exhaust port dividers

I'd guess the engine is a 59AB with a .060" overbore and a 4" stroke, perhaps via a Merc. crankshaft. FWIW.
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Old 12-16-2010, 07:28 PM   #11
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Default Re: exhaust port dividers

Flathead Fever, are you sure that Olds center exh divdider is made for the exh or just a suport for the lower center head bolt? Walt
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Old 12-16-2010, 07:44 PM   #12
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Default Re: exhaust port dividers

Quote:
Originally Posted by Walt Dupont--Me. View Post
Flathead Fever, are you sure that Olds center exh divdider is made for the exh or just a suport for the lower center head bolt? Walt
I think it does both.
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Old 12-17-2010, 05:37 AM   #13
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Default Re: exhaust port dividers

Quote:
Originally Posted by 36tbird View Post
I put them in an 8BA I am currently running. I don't have any quantitative analysis, but they just make sense to me. I was trying to address the cooling issue more than performance. That is, keeping the hot exhaust gasses from sharing the common area.

Maybe it is just me, but the dividers from Speedway do not mount where the instructions lead you to believe that they mount. That is, they look like they are held in place by the center stud. That places them too low in the passage and would act as a mega restriction. It took a lot of grinding and shaping, but I placed the dividers well up in the cavity directly between the valves. I drilled a hole into that cavity via the water passage exposed with the head off. I tapped the divider and used a stainless steel button head bolt sealed with JB Weld to hold it in place, see picture. Admittedly, probably a lot of work for not much gain, but what the heck.

You have to use kind of a Zen approach when you do this like I did. Feeling around with them in place, it does feel like a nice "coke bottle" shaped area and I always heard that is a good design for evacuating gasses.
Looks good .
Do you have more pics of the divider ?
Michael
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Old 12-17-2010, 07:48 AM   #14
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Default Re: exhaust port dividers

36tbird the engine is a 48 back 100 horse power block bored .60 over witn 49 to 53 Mercury 4" stroke crank. The dividers are held in by 7/16" allen screws (socket head cap screws) tignened into a counter sunk hole bored into the dividers. Those screws are in the bottom of the stud holes with the studs bottoming against them.
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Old 12-17-2010, 08:08 AM   #15
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Default Re: exhaust port dividers

Thanks for clarifying, Jim. Now I understand.

I was concerned about the dividers coming loose so when I first drilled the hole into the cavity and divider from the water jacket, I used the bit size required to tap a 10/24 hole. Then I removed the divider and tapped it for that size. (I've slept since doing this, but I think that is the size I used. I don't think anything bigger would be required.) I put JB Weld in that tapped hole and around the base of the button head to seal everything up and screwed it all together. I don't think it is coming loose.

Michael, sorry, I didn't take any pics of what the baffles wound up looking like. But, these are what I started with, http://www.speedwaymotors.com/Flathe...fles,3261.html. I think the hole I drilled and tapped wound up being where they had the countersunk hole in the divider to begin with. Like I said, you have to use a lot of Zen and hold your tongue just right as you feel your way along grinding and shaping those things to get them in place. Hope that makes sense.
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Old 12-17-2010, 10:20 AM   #16
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Default Re: exhaust port dividers

Quote:
Originally Posted by 36tbird View Post
Thanks for clarifying, Jim. Now I understand.

I was concerned about the dividers coming loose so when I first drilled the hole into the cavity and divider from the water jacket, I used the bit size required to tap a 10/24 hole. Then I removed the divider and tapped it for that size. (I've slept since doing this, but I think that is the size I used. I don't think anything bigger would be required.) I put JB Weld in that tapped hole and around the base of the button head to seal everything up and screwed it all together. I don't think it is coming loose.

Michael, sorry, I didn't take any pics of what the baffles wound up looking like. But, these are what I started with, http://www.speedwaymotors.com/Flathe...fles,3261.html. I think the hole I drilled and tapped wound up being where they had the countersunk hole in the divider to begin with. Like I said, you have to use a lot of Zen and hold your tongue just right as you feel your way along grinding and shaping those things to get them in place. Hope that makes sense.
Makes sense
Thanks
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Old 12-17-2010, 08:17 PM   #17
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Default Re: exhaust port dividers

Years ago I got dividers from Tony DiCosta at Hot Rod and Custom Supply in Fla. He is not there any more, and I don't know about the business itself. Those dividers looked a little rough but they fit very nicely, much better than the Speedway ones I had at that time. I don't know who made Tony's but they were a good product. I used the head stud to hold them and never had one move.
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Old 12-17-2010, 09:34 PM   #18
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Default Re: exhaust port dividers

Using a cut up 59ab block, I made a pattern for 1/8" stainless plate... Took a 7/16" nut, put it under the stud hole that runs into exhaust (exhaust valves out to access), marked finger tight position... Tig weld plate to nut, and use a long stud to hold them in place... Karl
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Old 12-17-2010, 09:35 PM   #19
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Haven'theard that name for quite awhild, did alote of business with him, great guy.
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Old 12-18-2010, 10:40 AM   #20
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Yeah Ron, I always had good dealings with him. I assume he is floating around out there somewhere.
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