change single exhaust to dual??

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Old June 9th, 2018, 10:05 AM
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change single exhaust to dual??

1969 rocket 350 with factory single exhaust...is there a good way to make this a deal exhaust system WITHOUT manifold swap? thanks..Rick
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Old June 9th, 2018, 10:16 AM
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Yes, you need to buy or fab a cap for the crossover pipe that runs between the 2 manifolds. Then purchase a factory dual exhaust kit, or let an exhaust shop make your system.

cap

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Old June 9th, 2018, 11:09 AM
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ok thanks a bunch, that's exactly what i needed to know...it CAN be done!
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Old June 9th, 2018, 11:18 AM
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Yes, its what the factory did.
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Old June 9th, 2018, 12:27 PM
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Originally Posted by razman427
is there a good way to make this a deal exhaust system WITHOUT manifold swap?
The manifolds were the same for single and dual exhaust - there are no "dual exhaust" SBO manifolds.
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Old June 9th, 2018, 12:42 PM
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Originally Posted by Fun71
The manifolds were the same for single and dual exhaust - there are no "dual exhaust" SBO manifolds.
Well Kenneth, actually there are, but I haven't heard good things about the Thornton 350 Juniors and they cost a lot to buy/ship.




I believe what your post meant to educate with is that there were no factory SBO manifolds. I agree. The N10 option block off plate is the way to go. I bought one from Inlinetube. Likely the same product as what Eric posted above from Supercars, but in a different package.
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Old June 9th, 2018, 03:33 PM
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thanks for all of the info, that cinches it for me, i'm gonna go with dual exhaust soon since i can do it the way the factory would have, without changing manifolds. now i just have to decide whether to get a 442 rear bumper for the tail pipes, or just turn the pipes down out the rear. thanks!
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Old June 9th, 2018, 03:59 PM
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If it's not a 442 (which would come automatically with the 400CID and dual exhausts) the N10 exhaust would be a dual exhaust with downturned tips at the stock rear bumper. If you like the look of the cutout exhaust and trumpet tips, go for it. It WILL increase the cost of your system by a fair margin though. It's aesthetics more than anything but we each have our own desires as to what the car should look like when finished. Your car, your build, your budget.
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Old June 9th, 2018, 06:06 PM
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Originally Posted by Allan R
Well Kenneth, actually there are, but I haven't heard good things about the Thornton 350 Juniors and they cost a lot to buy/ship.




I believe what your post meant to educate with is that there were no factory SBO manifolds. I agree. The N10 option block off plate is the way to go. I bought one from Inlinetube. Likely the same product as what Eric posted above from Supercars, but in a different package.
I bought these manifolds from Thorntons and it fits perfectly. I order just the 2 1/4" exhaust pipes from Inline Tube and supplied my own Dynomax super turbo mufflers.
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Old June 11th, 2018, 01:26 PM
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Originally Posted by ELY442
I bought these manifolds from Thorntons and it fits perfectly. I order just the 2 1/4" exhaust pipes from Inline Tube and supplied my own Dynomax super turbo mufflers.
I also have these on my 67. They fit fine. How much the little cast dividers help is debatable. Given how the PO solved the problem, these are much better. I did find an NOS set of true small block headers, but haven't been motivated to install them.

Tim
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Old June 11th, 2018, 09:28 PM
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Originally Posted by razman427
thanks for all of the info, that cinches it for me, i'm gonna go with dual exhaust soon since i can do it the way the factory would have, without changing manifolds. now i just have to decide whether to get a 442 rear bumper for the tail pipes, or just turn the pipes down out the rear. thanks!

I prefer the look of proper factory tailpipe turn-downs on a Cutlass...Just my opinion. (pretend you dont see the wing)

Many times this conversion is not performed properly. Such as lack of proper trumpet to bumper dimension or not installing the right tailpipe hangers or both.

Whatever direction you decide to go pay up for the aluminized mandrel bent pipes. I like the stainless steel band clamps vs the standard horseshoe style. Put everything together with a little dab of high temp anti-seize you will thank me the next time you need to take it apart.
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Old June 13th, 2018, 02:43 PM
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Originally Posted by droldsmorland
I prefer the look of proper factory tailpipe turn-downs on a Cutlass...Just my opinion. (pretend you dont see the wing)

Many times this conversion is not performed properly. Such as lack of proper trumpet to bumper dimension or not installing the right tailpipe hangers or both.

Whatever direction you decide to go pay up for the aluminized mandrel bent pipes. I like the stainless steel band clamps vs the standard horseshoe style. Put everything together with a little dab of high temp anti-seize you will thank me the next time you need to take it apart.
thanks a bunch, i like the look of your exhaust. beautiful car!!
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Old June 13th, 2018, 04:18 PM
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Thats not my car this is....but thanks.

Last edited by droldsmorland; June 26th, 2018 at 08:46 AM.
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Old June 13th, 2018, 04:42 PM
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WOW! well, your car is a BEAUT! thanks..
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