Damnit

"MM54" (mm54mk2) 10/03/2017 at 20:45 • Filed to: '71Chevelle, Project Hell

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This is hard to explain but easy to see, so bear with me. I’m trying to hook up my existing mufflers/tailpipe to the forced-upon-me-new headers. The issue that keeps coming after me is that the distance on-center between the collectors vs muffler inlets is far enough off from the old shortys (with downpipes I made) that I can’t get things lined up.

In order to have things square and lined up to the headers, the muffler inlets would need to be about 6" apart on-center, which isn’t possible. With the exhaust inlets where they should be, the collector pipes end up about 6" too wide (go figure) because of basic geometry.

This means that with both ends lined up, the collector flanges aren’t square and, unlike my awesome old headers, these don’t have ball collectors that let you make up some slop in that connection.

Unless anyone has a better idea, I think this means I’ll be heading back to Summit to spend more money I don’t have on a couple flex couplings (the braided sort of deal) to replace the H-pipe T’s. I’m upset that I’ll be losing the h-pipe (goodbye perfect exhaust sound) but at least it’ll be drivable.

OPPOsaurus WRX > MM54 10/03/2017 at 20:53

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stop by a local shop and have tho mo’fo’ welded in 5 minutes.

MM54 > OPPOsaurus WRX 10/03/2017 at 20:54

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It’s not a matter of welding it, it’s a matter of “these pipes do not have the right offset”

Die-Trying > MM54 10/03/2017 at 21:04

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can you put new/moved hangers on the mufflers? it sounds like you have the stuff up front so that it is mounting up, but it is the stuff in the rear holding you up.......

AestheticsInMotion > MM54 10/03/2017 at 21:10

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Adjust the hangers in back to shift the mufflers around as needed? Or weld in new ones? Idk, might not be getting exactly what you’re saying

Die-Trying > MM54 10/03/2017 at 21:10

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you can do some amazing things with a welder, and some strategically placed cuts......

HFV has no HFV. But somehow has 2 motorcycles > MM54 10/03/2017 at 21:12

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Make longer mounts for the miffflers. If they hand an half an inch lower it’ll line up...probably

MM54 > HFV has no HFV. But somehow has 2 motorcycles 10/03/2017 at 21:13

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it’s not height, it’s the distance between them. To make the pipes bolt up to the headers square, the muffler inlets would be 6" apart on center, AKA the mufflers up against eachother, passing through the differential through some magic.

MM54 > Die-Trying 10/03/2017 at 21:14

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That is true, and if I hadn’t spent way way more on this swap than planned I’d be able to do that, but somehow my “buy a welder” money disappeared into the abyss of parts for this

MM54 > AestheticsInMotion 10/03/2017 at 21:15

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For the mufflers to be the right distance apart they would be passing through eachother and the differential

MM54 > Die-Trying 10/03/2017 at 21:16

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The issue in the distance between the inlets of the mufflers. To get it where they would need to be to have the collectors bolt up square the muffers would be passing through eachother as well as the differential/driveshaft when the suspension moved. They’re already offset/offset too so there’s no cheat there.

It’s not so much that one side is working and the other isn’t, it’s that I can do either but it then doesn’t work on the other. The pipes go in towards eachother too much as you go to the back of the car for them to work with these headers.

Die-Trying > MM54 10/03/2017 at 21:18

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is there any way to move the hangers on the mufflers, to get things to line up better?

crowmolly > MM54 10/03/2017 at 21:19

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I’d make the header connection and then work my way rearward in the car. Move/remount the rest of the system as needed.

Can you spin the I-pipes to have the bends reversed, thus spreading the muffler inlets apart?

MM54 > Die-Trying 10/03/2017 at 21:22

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Nope. With the collectors lined up the muffler inlets would have to be 6" apart, aka passing through eachother and the differential/driveshaft.

MM54 > crowmolly 10/03/2017 at 21:22

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Nope, offset/offset so it could only be made worse.

Die-Trying > MM54 10/03/2017 at 21:25

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are you dead set on having full length exhaust, out the back of the car? or could you move the mufflers to just after the H, and put turndowns/turnouts out the side of the car?

just asking, there are otherways to skin a dead cat...... 

merged-5876237249235911857-hrw8uc > MM54 10/03/2017 at 21:28

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Put stubs out of the headers, then work the rear exhaust up to near the stubs, then buy a 90degree mandrel section of pipe to cut pie shapes out of to make the kink work out between the header stubs and the rear exhaust. That way you get a square seat at the header coupler and also hit the rest of the exhaust. If you can’t weld, then make the cuts and tape it together as well as index mark the pieces and run up to a muffler shop for them to weld it all up. Or run up t a shop to have them bend an s shape that will get from point a to b. But then you have kinked pipes, hence buying a mandrel section from summit to chop up.

MM54 > Die-Trying 10/03/2017 at 21:28

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I’d rather hack it together to get to drive it a couple times before everything becomes a salt-encrusted hellscape around here. Moving the mufflers and doing turndowns, etc would take more than slapping some flex couplers in place of the h pipe.

Also if it dumped below the car the oil smoke might fill the cabin. I don’t have valve guides anymore, and I can’t imagine the manual is going to help much.

crowmolly > MM54 10/03/2017 at 21:30

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https://www.summitracing.com/parts/sum-630850

Cheap enough for temporary use

RacinBob > MM54 10/03/2017 at 21:30

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Something like this doesn’t work?

https://www.ebay.com/i/302420073106?chn=ps&dispItem=1

MM54 > merged-5876237249235911857-hrw8uc 10/03/2017 at 21:33

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That would be the right way to do it (in theory I could pie-cut the existing Z-bend pipes in the second picture but I don’t own a welder, plus that section is stainless because the whole system used to be). Right now I need the easiest/cheapest route to be able to get it back on the ground. It has to go into storage before the end of the month (early November at the latest) and there’s the whole “I just swapped in a manual trans” thing to work out kinks with, too.

MM54 > crowmolly 10/03/2017 at 21:34

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This is $5.50 less per side :)

https://www.summitracing.com/oh/parts/aph-8848ib/overview/

Die-Trying > MM54 10/03/2017 at 21:36

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yeah, i can understand and appreciate those reasons........

valve guides, or stem seals? one is a whole lot easier to mend than the other......

merged-5876237249235911857-hrw8uc > MM54 10/03/2017 at 21:36

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Then if you can cut out enough of the kink pipes right now, you could run the pipes up to a muffler shop for welding. Or if you want to go ghetto with it to get it off to storage, just pick up a couple flex pipes in the proper diameter and clamp the in place for time being.

MM54 > RacinBob 10/03/2017 at 21:36

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If I can find one (well two) locally in the right size it could be just what I need. Time to search Summit

MM54 > RacinBob 10/03/2017 at 21:41

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You may have saved my h-pipe

https://www.summitracing.com/oh/parts/sum-672325/overview/

MM54 > Die-Trying 10/03/2017 at 21:44

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At 100k on an untouched ‘71 smallblock I’d tend to believe both. Vacuum gauge agrees.

RacinBob > MM54 10/04/2017 at 08:06

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Google search; exhaust ball and socket

RacinBob > MM54 10/04/2017 at 08:11

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By the way, a ball/flex joint is a good idea anyway as it decouples some of the weight off of the header when the engine rocks.