It's all a bit exhausting..

Technical MGB discussion
Paul Heffernan
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It's all a bit exhausting..

Post by Paul Heffernan » Fri Feb 07, 2020 11:52 am

Hi

Looking for some pointers. My '74 B came with a Stainless Sports exhaust, it's a Bell system same as this:

http://www.msc.parts/contents/en-uk/p82 ... 62-74.html

The thing is, it's a bit too "sporty" (AKA noisey) So, I'd like to calm things down a little. My problem is two fold, firstly as I've no previous MGB experience, I don't know what it's meant to sound like. Daft I know, but there you are.

The second part is, what are my options? The pipe is 2.5" diameter, and space is very limited. ie finding a suitable product that will fit into the existing pipe run and not "clash" anywhere.

I could just buy the same exhaust but with the standard centre box ie:

http://www.msc.parts/contents/en-uk/p82 ... IFOLD.html

But that seems quite a waste, as the system currently fitted is in perfect condition.

So, I'm looking for some advice ie who knows of a localish (I'm just South of Birmingham) specialist who would be able to offer a more viable (in both fit and cost) alternative.

Any advice will be gratefully received.
Ian Fozzard
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Re: It's all a bit exhausting..

Post by Ian Fozzard » Fri Feb 07, 2020 8:37 pm

Hi Paul,. very subjective of course, but I would say that a subdued growl would be usual in an MGB!

Not sure if your system is a single box system but if it is it could be a bit loud for me. An additional "bomb" silencer fitted mid system would be a good addition, fits the space well and is a common fitting. These I think are referred to as resonators in the USA, they modify the sound.

One other thing, if your exhaust is quite loud it could be that some or all of the packing has been blown out. This has happened to me with a stainless exhaust - the metal outlasts the stuffing! This made mine so loud it was unpleasant at Motorway speeds.

Ian F
Paul Heffernan
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Re: It's all a bit exhausting..

Post by Paul Heffernan » Sat Feb 08, 2020 1:12 pm

Ian Fozzard wrote:
> Hi Paul,. very subjective of course, but I would say that a subdued growl
> would be usual in an MGB!
>
> Not sure if your system is a single box system but if it is it could be a
> bit loud for me. An additional "bomb" silencer fitted mid system
> would be a good addition, fits the space well and is a common fitting.
> These I think are referred to as resonators in the USA, they modify the
> sound.
>
> One other thing, if your exhaust is quite loud it could be that some or all
> of the packing has been blown out. This has happened to me with a stainless
> exhaust - the metal outlasts the stuffing! This made mine so loud it was
> unpleasant at Motorway speeds.
>
> Ian F

Hi Ian, firstly thanks for the reply 👍

Dealing with your last point first, the exhaust has done around 600 miles since installed. Therefore I seriously doubt it's failed. However, as the first link shows, it is a single box silencer and big bore (2.5") pipes. Thing is, it's not too bad when tootling along, it's under acceleration and in towns etc that it's quite intrusive.

As for your first point, as I mentioned I'm not too sure what a B should sound like as I've never owned one before. The last time I drove one was around 40 years ago!

So, I planned to fit a muffler, and have a Magnaflow "Bomb" that came with the car. It's brand new in it's box but it's too long to fit in the only straight part of the pipework. I have (since posting my question) managed to source a shorter version but it's for 2.25" pipe (mine's 2.5") so it'll need fettling. It's also 4" overall dia instead of 3.5", but I think that'll be OK. Just need to see if I can get a reducer to fit.

I'm hopeful that fitting the "bomb" will calm things down a little. Otherwise, it looks like I'll have to swap the whole thing out for a twin box standard system. Not too keen on that though.
Ian Fozzard
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Re: It's all a bit exhausting..

Post by Ian Fozzard » Sat Feb 08, 2020 1:44 pm

Thanks Paul. I wouldn't recommend a standard system with the larger first box - very prone to damage. My BGT has always had a pronounced hump under the passenger seat caused, I am sure, by the original big box which was fitted there!!

Ian F
Vic Butler
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Re: It's all a bit exhausting..

Post by Vic Butler » Sat Feb 08, 2020 5:36 pm

Paul, my BGT has a large bore stainless steel exhaust and matching manifold with a single rear silencer and I don't find it noisy. My system is a Double S one.
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Peter Cresswell
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Re: It's all a bit exhausting..

Post by Peter Cresswell » Sat Feb 08, 2020 9:07 pm

Hi Paul,
I am using the Maniflow rally system. The 3 branch front pipes are Part No. STR 630 and the system is STR 700 which is a twin box system. The car is very quiet as the system meets the Night Road Rally noise check regs. it is 1 3/4 in bore so slightly larger than standard and is made from heavy gauge mild steel with skid plates on the rear silencer. The centre box is a bomb type and the rear silencer is much larger diameter than the standard box. It uses the standard mounting, although I did modify the centre one to tuck the system up closer to the bottom of the car.
My car is lowered by 2 inches over standard so I can testify it will take a lot of abuse and is very strong. It can be fitted to standard front pipes but you would need some sort of adaptor to fit it. It also comes with all the clamps needed which are the circular type with a single side bolt, and unlike the U-Clamp type clamps they don't hang down lower than the system, so don't get damaged threads should you need to take it off.
I got mine from Brown and Gammons, but Maniflow will supply direct and will supply any silencer boxes you might specify.
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John Watson
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Re: It's all a bit exhausting..

Post by John Watson » Sun Feb 09, 2020 11:30 am

I have a Maniflow system, they are in Salisbury SP2 7PY and will produce what spec you want.
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Paul Hollingworth
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Re: It's all a bit exhausting..

Post by Paul Hollingworth » Sun Feb 09, 2020 2:55 pm

My friend has the Moss 'Tourist trophy' exhaust on his B and he's very pleased with it. Its a single box stainless system with tubular manifold. His car has some performance enhancements shall we say. The exhaust is not particularly noisy inside the car he says and I don't think its much different than any other B from outside. We don't remember exactly what diameter it is but we think less than 2". It will set you back £400+ Your system at 2 1/2 " just sounds too big to me. Mind you I've got a bog standard system on my B from Manners. (tight or what)
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Paul Heffernan
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Re: It's all a bit exhausting..

Post by Paul Heffernan » Sun Feb 09, 2020 5:54 pm

Thanks for all the advice, much appreciated. I'm thinking as I can get the "bomb" for free, I'll get it fitted and fingers crossed that'll do it. If not, I'm inclind to agree with Paul Hollingsworth ie 2.5" diameter is rather large, so I may just bite the bullet and replace the whole thing.

Watch this space!
Paul Heffernan
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Re: It's all a bit exhausting..

Post by Paul Heffernan » Mon Feb 10, 2020 12:51 pm

My bad........ the main length of exhaust pipe is 2" dia (Not 2.5 as I said before) It's only the polished section of the exhaust tip that's 2.5"

My understanding is that the pipe diameter measures given are external. So, I've got (sale or return) 2 mufflers, one is 2.25" and the other is 2" but these are measured internal diameter. So, fingers crossed the 2" one will slot onto the pipe.
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