MM exhaust system

for those with Series MM sidevalve cars produced between September 1948 and February 1953

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RobThomas
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MM exhaust system

Postby RobThomas » Mon May 16, 2016 2:57 pm

[frame]Image[/frame]
[frame]Image[/frame]
These photos above are from part-way through the process of making a new inlet/exhaust system for the MM that will also fit the Alta engine. From here back I have a stainless flexi section from Ebay...[frame]Image[/frame]
http://www.ebay.co.uk/itm/ANY-SIZE-Exha ... hash=item0

...with a motorbike stainless silencer in the normal Morris position...[frame]Image[/frame]


...that made a huge amount of noise. Far too much so I have some Mini and MG Midget silencer boxes on order that will either fit between the tank and left damper or will turn 90 degrees and sit behind the tank and beneath the bumper. More info to follow as I develop it a bit further.
Cardiff, UK

seriesmm_1
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Re: MM exhaust system

Postby seriesmm_1 » Mon May 16, 2016 3:56 pm

Nice photos Rob,
A faver could you please forward the size of your wooden battery tray to me as I need to make one up for my rebuild.
Email address moggy1000@gmail.com
Many thanks
BrianR


RobThomas
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Re: MM exhaust system

Postby RobThomas » Mon May 16, 2016 7:02 pm

Will do, Brian.

I had tried to get an 096 battery in there but couldn't quite do it. I'll post the info for you tomorrow morning.

Rob
Cardiff, UK

RobThomas
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Re: MM exhaust system

Postby RobThomas » Tue May 17, 2016 11:55 am

E-mail sent with dimensions etc.
Cardiff, UK

seriesmm_1
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Re: MM exhaust system

Postby seriesmm_1 » Tue May 17, 2016 12:13 pm

Many thanks Rob
BrianR


youngcamper
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Re: MM exhaust system

Postby youngcamper » Tue May 17, 2016 12:52 pm

RobThomas wrote:[frame]Image[/frame]
[frame]Image[/frame]
These photos above are from part-way through the process of making a new inlet/exhaust system for the MM that will also fit the Alta engine.
The Manifold looks tasty!

Did you make it yourself? I'd appreciate some more pictures of this/dimensions if possible.

Thanks,
Will
ImageImageImage
________1967-Lily________________________1963-Phoebe_______________________1965-Dobby_________

RobThomas
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Re: MM exhaust system

Postby RobThomas » Tue May 17, 2016 5:34 pm

Sure!

https://www.smallfordspares.co.uk/produ ... fold-plate

These were the starting point. Someone on here (Tortron??) mentioned that the bolt pattern for the Ford was the same as the MM. I didn't know for certain that this was the case so rather than spend money on the Ford one I made a pattern in CAD from a standard MM manifold. Ended up being cheaper to get one laser cut locally so was a saving.

Image

I bought a motorbike exhaust from a scrapyard (FZR-something) that supplied the 4 curved downpipe sections. It was fairly new so didn't need much cleaning. I cut the 4 pipes to reach the same level and cut 4 holes in a steel plate to go over the end of the 4 holes. I welded from beneath to get good access and then folded a piece of steel to 'cone' down from the size of the 4 pipes to about 1.5 inches i.d.

The other curves at the bottom of the pipe are just bits of old Marina exhaust and some leftovers from the motorbike.

At the top end I welded the outer faces of the tubes to the big plate and then TIG brazed the insides to get a nice smooth transition. The inlet cost about £20 to be mandrel bent to my specs. Just 2 bends on a metre of steel tube. I had to flatten it to go from round to square for the MM head.


Image

I wanted a single carb for simplicity and then added a little ram pipe for the inlet by forcing an Ali tube over a cone in a bench vice before hammering the ends around a piece of bent rod.

Image

I made one for a friend to fit the pre-war Minor but all the tubes were new custom-bent tubes. Total cost to build was nearly £250.
Image

Next was to copy this silencer/manifold from an Austin. Again, not a complex shape apart from the flange at the bottom. The nose cone was made from 2 pieces of flat sheet bludgeoned into shape using a BFH and a hollowed-out tree stump.
Image
Image
Image
Image

I added these other pics to show what can be done with a little ingenuity and some time.
Cardiff, UK

RobThomas
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Re: MM exhaust system

Postby RobThomas » Tue May 17, 2016 5:38 pm

https://www.smallfordspares.co.uk/produ ... manifold-1

A cheap-ish option if you want to save some time?
Cardiff, UK

panky
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Re: MM exhaust system

Postby panky » Tue May 17, 2016 5:52 pm

Mightily impressed 8)
Image

RobThomas
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Re: MM exhaust system

Postby RobThomas » Wed May 18, 2016 6:16 pm

All done. Mini system (£29 inc P&P) supplied 2 silencer cans at 14.5 inch length by 4 inch diameter. Not quite enough room to comfortably hang one beside the tank so mounted it sideways across under the bit of the boot floor where the catch sits. 90 degree bend came from a VW Beetle (Called a J-tube) and then just added some hanging hardware. Much quieter but still with a deep rumble to it. I'll add some pics when able.
Cardiff, UK

RobThomas
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Re: MM exhaust system

Postby RobThomas » Sun Jun 12, 2016 4:35 pm

Taken a bit longer than expected due to the upholstery being fitted in between other jobs. Exhaust now hung at the back and it is a lot quieter, almost as quiet as my other MM.[frame]Image[/frame]
Cardiff, UK

tortron
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Re: MM exhaust system

Postby tortron » Fri Aug 12, 2016 10:44 pm

How do you find the inlet manifold? I imagine it might benefit with preheating from the exhaust due to the length and bends

Here is a ford 93E gasket over a SMM flange. Image

RobThomas
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Re: MM exhaust system

Postby RobThomas » Sat Aug 13, 2016 10:24 am

Ah, yes. Since then I've clamped a sheet of copper to the inlet pipe and then laid it against the exhaust pipe. No icing so far and happy running an EK needle apart from a slight lean at very slow idle. The copper comes from the roofing sheets they used on a building in Cardiff.

The next manifold I plan to do will have a shorter inlet run with slacker curves and a smoother transition just after the carb. Having a heat transfer seems like a good idea, now that I've read up on the subject. Better atomisation.

Do you have any more 'after' pictures of the Aquaplane manifold? I know you did a bit of grinding on it.

Thanks.

Rob
Cardiff, UK


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