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Mgb exhaust

Posted: Fri Oct 16, 2020 9:47 am
by Kilroy
Hey all.
During my current Estate rebuild a friend suggested that I should make it sound like an MGB.
Not a bad idea actually.
What I would like to know is how different is the Marina front downpipe setup as compared to mgb.?
Perhaps they are interchangeable.?
To my knowledge the mgb used a front muffler and a rear resonator.
Not sure if either or both of those were in any way special.
Having spent some time searching locally for mgb mufflers and failing, I am thinking that I need to involve mgb people.
Seems a bit of a comedown for a Marina owner....

Interested in anyone's insight.
Thanks.

Re: Mgb exhaust

Posted: Fri Oct 16, 2020 12:57 pm
by MarinaCoupe
The cast iron exhaust manifolds are essentially the same, the twin down-pipes on the Marina are slightly shorter than the MGB. The other variable could be the internal diameter of the main system could be different, which will produce a different resonance.

Re: Mgb exhaust

Posted: Fri Oct 16, 2020 1:35 pm
by david painter
On my MGB The main silencer is just forward of the rear axle U bend It is a straight though silencer unlike the Marina offset one is also slightly longer from memory with a similar diameter ( I can check actual dia if required) the rear resonator box is again similar diameter to Marina one it is also again longer with down turned tailpipe i think both would fit though
Dave

Re: Mgb exhaust

Posted: Fri Oct 16, 2020 10:38 pm
by Kilroy
Thank you both.
Looks like I am on a muffler hunt.

Re: Mgb exhaust

Posted: Sat Oct 17, 2020 10:05 am
by ClaytonSpeed
The UK TCs with mild steel pipes and their original 'torpedo' rear resonator always sounded far better than any MGB I've heard or driven.

Isn't the MGB is a shorter car? That might have an effect on what it will end up sounding like.


Ben

Re: Mgb exhaust

Posted: Mon Oct 19, 2020 1:43 am
by locost_bryan
My nieghbour's had a NZ new HL that sounded exactly like an MGB, wonder if NZMC specified MGB-style mufflers, since the exhaust system was made locally?

MGB forums say 1 5/8" ID (1 7/8" OD) tailpipe is standard, recommend 1 7/8" ID (2" OD) for a 100-120bhp engine.
http://www.superstreetonline.com/how-to ... w-exhaust/

Re: Mgb exhaust

Posted: Mon Oct 19, 2020 7:39 am
by Kilroy
Thanks for the info guys.
I have no idea what was originally fitted as all now seem to possess replacement items that often do not look as though they were designed to fit in the space provided.
Was the original front muffler on the Marina an offset type or were the pipes central both ends..?

Re: Mgb exhaust

Posted: Mon Oct 19, 2020 7:43 am
by david painter
Centre UK Silencer was offset with what looked like e perforated baffle inside
Dave

Re: Mgb exhaust

Posted: Mon Oct 19, 2020 7:46 am
by Kilroy
Thank you Dave.

Re: Mgb exhaust

Posted: Mon Oct 19, 2020 7:51 am
by ClaytonSpeed
The MGB factory mid exhaust box in this shot from Bryan's link looks very similar to the RC40 as used on minis:
172238522.jpg
image.jpeg
image.jpeg (5.83 KiB) Viewed 8115 times
Obviously with straight in/out pipes. Now, they do sound nice on B series engines.

Re: Mgb exhaust

Posted: Mon Oct 19, 2020 9:05 pm
by locost_bryan
Not really relevant for the B engine, but this Marina 6 rear muffler system is for sale on ebay Australia (for $400!). Appears to be just the single muffler.

Nos Repco Leyland Marina 2.6L Exhaust Rear Muffler System M2859

Image

Re: Mgb exhaust

Posted: Tue Oct 20, 2020 5:48 am
by Kilroy
Maybe they would sell me 2/3 of it...

Re: Mgb exhaust

Posted: Tue Oct 20, 2020 10:05 pm
by MARINAMADBAZ
my gt has no rear silencer just a straight thru pipe after the Swan neck sounds great!

Re: Mgb exhaust

Posted: Wed Oct 21, 2020 8:38 am
by Kilroy
I was running the same setup on the yellow car prior to removing the engine for use in the estate.
While it sounded pretty business, there was a harsh quality to the sound that did not please me, hence my idea that the use of a resonator might smooth the sound out a bit without muffling too much.
This was the old exhaust, which does not fit on the estate as the rear valance arrangement is different...

https://www.youtube.com/watch?v=FSTvNg4571E

Loud mechanical noise from the engine bay was the water pump announcing its demise.
Now replaced.