The Stovebolt Site Forums The Shop Area Engine Shop splitting my exhaust manny

I'm about to cut my exhaust manifold for my 261 into a split header. Last night I figured the best place to cut was behind the heat riser. This would "hide" the split from immediate view. Reading some previous discussions it seems others have cut them in front. I'd like to hear from anyone who has made their own headers from a manny. How and where was it done? I would be interested in writing a tech tip when I'm done so any input will be taken into account.

cheers,

Ryan

MY uncle has made several of these for me over the years. He cuts a slit in the back of the manifold just behind the heat riser (like you were thinking of doing) cuts a chunk of steel, grinds it down to fit in the slot, then cuts a hole in the bottom of the manifold as close to the rear as possible and welds in a piece of two inch water pipe (very thick walled). There is one of these on my old '57 210 (I don't own the car anymore but, it's still in town). It's going on 20 years old!

I am thinking of going this route.
Kansas customs

[img]http://www.inliners.org/Advertisers/split4.jpg[/img]

I'm picking up a 235 on friday that has a home-split manifold. I will post pics when I get it home.

how are they welded? I've been talking to several people, some say TIG, some say Braze. We have a large oven in the forge at work here, so what I'm thinking of doing is setting the temp high, brazing the joints, then popping the hot manifolds into the oven, turn it off, and let it cool slowly overnight. The consensus seems to be that unless the TIG is perfect, it will crack over time, and the problem with brazing is it tends to crack as it cools rapidly (dissimilar metals). Any thoughts?

thanks,

Ryan

Here's a good source of info on welding cast iron.
Lock N Stitch

Tony, I like those manifolds. Thats what I've been looking for something to retain the heat riser.

update - Split the manifold yesterday. Found a good donor manifold to supply the second exhaust output and allow a bit of cast iron "welding" practise. Will be trying a couple different methods, but instead of using the forge oven, I have decided to use an old oven I found at the recycling depot to see if the average Joe can do this himself or not. Anyone should be able to find an old oven (hey, I found one in 45 minutes and it was free!). Stopped in at the local welding shop for some pointers as well. Their advice - heat the manny up to as high as the oven will go, try a bit of Tig, try a bit of brazing, and try a bit of arc. Pop it back in the oven, turn the oven off and take it out the next day. Will keep posted of results.

cheers,

ryan

Thanks Fred, there is some very good info at that site! More research is in order.

Ryan

Has anybody used the Kansas Custom split manifold? If so, did you get any power boost or was it for the dual sound? Did you use a crossover pipe or keep them separate? Any problems with fit?

Richard - you won't get much of a power boost by just splitting the manifold, but it is the first step to higher power. To get more go you need more flow from the carbs through to the exhaust. To do this you also need more carb (larger or more of them), and a cam with more lift and duration. This gives you better cylinder fill and more power, the split exhaust just lets you dump this larger amount of gas on the exhaust stroke. What you do get right away is the sound...the glorious sound that only a straight six on dual exhaust makes!

cheers,

Ryan

I will let you know in about two weeks. I just ordered mine.