yea only @ idle and no louder than the rest of the exhaust. I had always heard that a true split header would do that but all I have owned before was a split stock manifold and this is my first 235 with a cam in it. thanks for breaking it down paul!
also guys remember if you are going to split your own by cutting a stock one and adding a dump tube make sure you get as clean of a manifold as possible! starting with a clean one as opposed to a really heavily pitted one will make your life so much easier. the really heavily pitted ones are VERY impregnated with carbon making them almost impossible to weld correctly. also remember folks we are welding cast so after you tack them together get a buddy to heat them cherry red before you start welding them up. the pic posted earlier of (I believe Heny J's) shows how nice they can look if you have a clean manifold to start with...
>>>>>,Did it to my '47 Chevy in '57 ,,and had Hooker Hedders on a 302 Jimmy Six with a Wayne 12 port head & 5 Stromberg 97's in a '31 Model A in '59,,and my '52 Chevy in '63 ,,but,,the trick to it is the mufflers ,,,gotta have a pair of Smittys Glass Paks ,,, IT's THE SOUND !!! Nuthin' Like It On Da Planet ,,
flathead mopar 6,chevy 6,flathead ford 6, can only be split 3-3 ohv ford sixes can only be split 4=2 0r 2-4 i split many and that's the way they are. there is no way to get a 4-2 chevy split or a 3-3 ohv ford six split. unless you make some weird tube headers.
I've got a 51 Pontiac with a 239 flathead six, and several spare manifolds to play with. Cyl's 3&4 have a common port, so would it be better to split it 12 and 3456, or 1234 and 56 ? Does it matter which way you go for the sound ???
In my book I love the sound. Yes yu do pick up performance. Split manifold is simular to putting on a set of headers. Get that exhaust out easier. Flathead 6 Mopars manifold give you an even 3 X 3 exhaust when you cut out the heat riser.Chevy is difficult because the original outlet is in the center. If I can figure a way to post some photos to this I will show you a manifold I just split for my 47 Dodge pickup. Done some this way back in the late 50s,early 60s.
Taking a closer look at it tonight, I've got a lot more room for pairing the 5/6 ports to fit the exhaust out. As the photo shows the is actually 2 ports for 3&4 coming out of the block, but they are common to a single port on the manifold.
Country, I really dig the way you split that stock manifold! looks great. i have always wanted to do a stock one like that then clean it up real pretty and have it chromed also someone said earlier that you cant split a chevy 6 in 2/4. depends on where you put the dump and where you weld in the block off plate. that is of course adding a dump to a stock manifold and adding a barrier in between. I did that once and drilled a 3/8 hole in the barrier and that was the best sounding six I have ever heard!
If you remove the intake manifold, you may see that you could acess the siamesed center exhaust port through the heat riser area and weld in a divider plate that would separate 3 and 4, allowing an even 3-3 split.
Yeah "hotdamn. Thank you. I would opt for ceramic powdercoat over chrome. Have you ever seen some of these coated headers. You got to look close to tell the diifference between that and stainless. My manifold was pretty pitted, but it will do. Just did them with high temp. header paint and cured them with the "Bluewrench" Next step is my tube 2-carb intake.
I know we all love the sound, but I was told by some of the inliner drag racers that bringing them back together into a larger diameter pipe will increase performance. Something bout consistant back pressure? ie: spilt 1"7/8 into a single 3" tube. Anyone elese heard this before?
>>>>>,There was a story goin' around in the late '50's ,,,split a Chevy six bangers exhaust ,,put a pair of Smitty's on it & run the tail pipes all the way out below the rear bumper with a pair of nice pincel tips ,,THEN ,,string a low key piano wire from pincel tip to pincel tip ,,,go wind it up ,,and it will shatter windows ,,,,SO ,,i tried that on my '47 Chevy Fleetline ,,did it just like they said in Rod & Custom ,,went downtown Marshalltown ,Iowa ,,,wound it up between all those shops w' those big plate glass windows ,,Bingo ,,i shattered a dozen of em ,,the cops were still lookin' for who did that when i joined the Air Force in '61 ,,
>>>>>,Just like in '59 when Bob Nall ( the Adult Toy Factory guy in Las Cruces ) ,and I flushed M-80's down the toilets at the "Y" ,,and blew up the whole sewer pipe system ,,and when the cops showed up ,,him n I were on the roof thowing water ballons at the cop cars ,,,we escaped down the fire escape ladders and ran down the alley to his '49 Chevy ,,i think they're still lookin' for who did that ,,lol,,lol,,
>>>>>,Ha ,,Ha,,,Ha,,,OhBoy the '50's sure were fun ,,,Rock n Roll ,,Short Skirts and Chevrolets ,, couldn't get no better ,,,
This dual manifold/collector design is pretty much the same configuration as Jaguar 3.8 and 4.2 sixes. Basically the reasoning is this configuration assists in pulling or scavenging the exhaust pulse from the next cylinder in the firing order from the pressure of the cylinder that just fired. If that makes sense..... Simply adding another port to a log type exhaust manifold may help exhaust exit quicker, but will not be nearly as beneficial from a performance standpoint as the design shown above.
And if you turn that graph sideways and read it like musical notes it is the Melody to "All My Lovin" by the Beatles...
I split a 48 chevy in 1952. I cut a slot in the manifold close to the main outlet and welded a plate in place. You could close it up all the way or you could leave a small gap between the front and rear cylinders to eliminate the back fireing and popping sound that would come with a purchased header that replaced the back half of the manifold. If done properly and the right mufflers it would sound fantastic. (IN THOSE DAYS THEY WERE STEEL PACKED MUFFLERS INSTEAD OF FIBREGLASS). Then you welded your rear outlet in place. Was a lot cheaper than a header and sounded as good. Remember, back then there weren't a lot of ohv v8 cars around so flat head sixes with split manifolds were pretty common.
If you listen to the old Big Healeys and (I believe) the Jag straight 6's, which had split manifolds based on the firing order, it sounds much smoother for the exact reason you note: http://www.youtube.com/watch?v=hkXGLcBbFoo That's music!!! It also helps to keep in mind that most 6's are not big engines, the Healeys used true duals at about 1.25" to keep the velocity up. Just a wonderful sound...
I almost did that with my 48 fleetline in 1956 with split manifold and dual straight pipes. Needless to say, straight pipes weren't on but a couple of days.
Did the 2/4 chevy split. 1 and 6 together, 2-3 & 4-5 together. This may sound like a terrible idea; but consider the firing order. 153624. 1 and 6 are exaclty opposite each other, and 5-3 then 2-4 are as well. You will get a different velocity out of each tailpipe; and it may not be using the best possible arrangement for power; but it sure sounds good; and pulls like it is doing much better than stock! It doesn't sound like a 6 anymore, sounds more like an oddfire V8. Using a homemade 2-chamber welded mufflers; similar inside to a delta flow muffler...
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