MG Midget Madness (i.e. It was either this or kill it with fire)

[RXtacy]

Originally Posted by GySgtFrank

Thanks Mike. This part took a lot longer than I figured it would, but it should work.

They always do.

[chibikougan]

So when ya starting it up then?

[GySgtFrank]

Originally Posted by chibikougan

So when ya starting it up then?

Don't start with the "are we there yet" crap or I'll come back there and paddle your behind.

[GySgtFrank]

After a protracted struggle I finished modifying my muffler.

muffler - after modifications by Kevin Frank, on Flickr


I replaced the two 2.5 inch outlet pipes with 1.75 ID pipes (same as the header pipes). I'm hoping that by decreasing the size of the outlet pipes it will help to muffle the noise a little better. Getting the bottom pipe to make multiple curves in a lot of directions, so that it would exit in the correct place, was a real nightmare. I had to cut it off and re-section it 4 times to get it right. At this point I think it has as many welds on it as it does pipe. Getting the top pipe to exit inline with, and on the same angle, as the bottom wasn't easy. It was a lot easier than the bottom pipe though.

and a picture with the muffler in (before hanging it permanently) showing the exhaust tips exiting where I wanted them to.


tail pipes - before hanging muffler by Kevin Frank, on Flickr


I have to get the muffler hung and then on to the rest of the exhaust system.

[chibikougan]

Saweeeeeeet!

[GySgtFrank]

I am going to document how I got the muffler mounted in the tight space I have to work with. This may seem like piddley details to some, but if you've ever had to mount an exhaust and muffler into a tight space (where you could not have a lot of movement) you will know that it is important. Get it wrong and it will cause you no end of headaches.

The mounts that I am using are a common mount you can get from most muffler shops. It is a fully captured rubber mount. This makes it possible to isolate movement in all directions (with the use of jams nuts on the center mounting rod), but still maintain rubber isolation between the exhaust system and the body of the car. There is still some movement so that I "hopefully" don't break anything, but not enough for it to contact any of the surrounding metal when I hit bumps.


exhaust mounts by Kevin Frank, on Flickr


I used 1/2" threaded dowel to make the hangers so that I could adjust the position of the mounting point and secure it down with jam nuts on either side of the rubber block. I used three mounting points so that it stayed secured in all directions and could be moved into the optimum position. The inlet side has two mounts, top and bottom, the outlet side has only one mount up top. Mount on inlet side:


muffler mounts - inlet side by Kevin Frank, on Flickr


Mount on outlet side:


muffler mount - exit side by Kevin Frank, on Flickr


These are the pictures of how I mounted it in the box. It doesn't look like it in the pictures, but there is at least one inch of air space all around the muffler. The box sides act as a heat shield to minimize heat transfer to the fuel tank and the body.


muffler - mounted 1 by Kevin Frank, on Flickr


muffler - mounted 2 by Kevin Frank, on Flickr


... and another picture of how the muffler and tailpipes actually ended up looking from the rear once mounted. I was pretty happy with it, as it came out just the way I wanted it to.


muffler - mounted bottom by Kevin Frank, on Flickr

[hades]

Good job

[GySgtFrank]

Originally Posted by hades

Good job

Thanks Jeff, it's getting there. It will be fun to put paid to a lot of the rotary haters on some of the Brit car forums. It is amazing how people can have such definite opinions about something they know so little about. They drink gas, they have no torque, they use oil, they only work for autocross, blah, blah, blah. To be fair there are quite a few supporters over there as well. If this doesn't work as planned I'm going to be eating a LOT of crow however.

[TitaniumTT]

Looks really fucking good man! I'm digging it and looking forward to seeing it finished!
Got a line on an engineer harness for you, should know more soon, like weekendish time. Pretty sure I just tossed the ECU so I may have to source one of those too

[GySgtFrank]

Originally Posted by TitaniumTT

Looks really fucking good man! I'm digging it and looking forward to seeing it finished!
Got a line on an engineer harness for you, should know more soon, like weekendish time. Pretty sure I just tossed the ECU so I may have to source one of those too

Thanks for the kind words. Sounds good on the harness. I can always use my existing ECU. It unplugs easily enough. I really didn't want to have to start cutting wiring harnesses out of the 79 after what I went through to get them in there in the first place.

[TitaniumTT]

I hear ya cuz... No need for that shit... Get a meecrowreck before that happens

[GySgtFrank]

I had to build a merge collector to feed the two 1.75 inch ID pipes into the single 2.5 inch ID inlet for my muffler. It was a far bigger chore than it had any right to be. I had planned to use a header collector flange that would allow me to swivel the pipe around to make it fit if I moved the muffler. Unfortunately I couldn't find that style of 2.5 inch collector that would fit my existing flange on the muffler. If I had to do it over again, I would cut the flange off the muffler and use the other style flange, but I didn't, so this will have to work.


muffler merge collector 1 by Kevin Frank, on Flickr


muffler merge collector 2 by Kevin Frank, on Flickr


muffler merge collector 3 by Kevin Frank, on Flickr


I used a 2.5 inch ID flange that would fit my muffler flange, a short section of 2.5 inch ID exhaust pipe, and two short pieces of 1.75 inch ID (2" OD) to make the piece. I had to split and form the 2.5" pipe in four directions after it was welded to the flange. I then formed it onto the two short pieces of 2" OD pipe, that I had already welded together, and tacked it down. I cut out and formed some fill pieces for the gaps where the split pipe no longer covered and put a lot of welds inside and out to ensure that I have no leaks. Clean up on all those welds was not fun. As I said, far more work than was reasonable. I would suggest using an off the shelf part if at all possible, the high cost of parts like this are for a reason, time and effort. I couldn't as no one makes a part like this to join the pieces that I am planning to use.

This piece will allow me to connect the two pipes side by side to be run over and dropped down with 90s. They will run forward between the fuel tank and frame rail, one stacked on top of the other with a small gap between them. It is going to be enough of a battle trying to get the pipes in the right position without having to worry about the fit at the muffler end as well.

[chibikougan]

Where ya bored?


Looks good and like its gonna work...

[GySgtFrank]

Thanks Ransom. It took way too long for one stupid little part.

[speedjunkie]

^I hate when that happens. One little thing takes forever and you feel like you got nothing done. Not quite infuriating, more annoying I think.