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MG MGB Technical - Exhaust manifold

hi,

i just bought a second-hand exhaust manifold and it's in pretty good condition i think it has never been used... i want to clean it a bit from a very superficial rust and then paint it with a high temperature paint for exhaust, do you think it's a good idea? i know it's better wiht the ceramic stuff to put on it but i take the option of painting...
Secondly I can't know really which kind of exhaust mani it is, i think it might be a performance one large bore it is like the one on the right on the Moss website : http://www.moss-europe.co.uk/MossUK/ProductList.aspx?SubSubCategoryID=MGB_UMGB-220 but the tube behind the exhaust manifold is in my case in front of the two others linked by the bigger thing (sorry i'm not very clear..)do you think it will fit my GT 1800 from 1972?
thanks a lot
Alexia
Alexia

Hello,


It is definitely an hedders(headers) or extractor manifold as the brits will tell. It will fit your engine very well but usually it need some ajustment at flange level as it is not at same thickness. Do not take ceramic coating or regular wrapping route as it retains too much heat and could be desastrous for the engine. Furthermore it is expensive for nothing. You must have in mind that you are not a racer and a B is not that kind of car. A paint with hi-heat resistance will be fine. I have an ANSA type for years on my '73B and very happy with it. You will not notice a real performance improvement, just may be in your mind, as it could be a bit noisier. I used a stebro free-flow exhaust with mine and it terrorises neiberhood if I rev too much the engine...

Cheers,

JGC
Jean Guy Catford

Alexia,
There are several schools of thought out there on headers and original exhaust manifolds and I have found that the original exhaust manifold is a header if you look at the length of each pipe. They are about the same. A friend of mine several years ago told me that he actually found thru racing that the original exhaust manifold like the type that you have originally on your 72 actually provides more torque. Some of you racers may know for sure. It is heavier than these aftermarket headers is its only downside as best as I can tell from years of experience. The original breather cans that people like to chuck are actually cold air boxes with mini velocity stacks inside them. When I install twin SU's on later Stromberg cars I always use this exhaust manifold when available and install the aluminum breather can bases inside the new pancake airfilters that I have to use to clear the brake boosters.
M. Whitt

thanks guys,
effectively my exhaust is from a GT 72 do that's a perfect match with mine and after some sandpaper work it's seems to be in a very good condition
I have to buy the silencer and the rest of the exhaust system... so don't know yet which one? do you think I have to ask to an mg specialist to fit the exhaust manifold as it's slightly different from mine currently or can i ask to a normal garage ?? i'm considering more the MG's way but ...
and do you think I could swap my black original air filters for the K&N ones ??
yes Jean-Guy I will paint it in a red exhaust paint!!
cheers
Alexia
Alexia

Allo Alexia,


I have tried many set-up for my B. The easiest way is going Moss with something near originality. They offer also Falcon stainless steel route but more expensive. There is aftermarket Bosal or Walker that still carries some parts. I don't know if you are in america but once I have used two red bullet(Thrush glasspack) free flow and a custom made exhaust tubing except for front Y-pipe. The result was very good.

Cheers,

JGC
Jean Guy Catford

The Falcon SS exhaust is a very good product. I use this on my GT with a stock manifold and it even sounds very close to the distinctive sound that the B should have. My roadster has a Double S stainless system with a performance manifold very like the one you refer to. Sounds like a cement mixer on a building site. It's in for a change !
Iain MacKintosh

ok i'll look the SS which is cheaper and i definetely want to keep the right noise !!
thanks
Alexia

I disagree that header wrap or ceramic is unnecessary or even bad for the engine. Indeed they are both very good for the engine and for keeping underbonnet temps down. They do, however, cause faster erosion of the mild steel tubing and hence faster replacement. The wrap also tends to lead to corrosion due to holding moisture.

The stock manifold is magical for torque but heavy as hades.

My exhaust is a 1 5/8" Tri-Mil tri-y with a straight 2.25" tube back to a cheapo 2.5" "cherry bomb" beside the gas tank. Sounds lovely.

Mike!
mike!

what do you think about the peco? do someone have one?
i check yesterday and the shape of the exhaust manifold i have is really like the peco one and Peco is a bit cheaper than the others....
Alexia

Peco/Falcon both good.

Paint will slowly turn white but extend the life of this relatively short life manifd.

The 'right' tubulars will produce about 2% more power plus more noise during acceleration but not change the cruising note much (slightly tinny rattle). Tape will reduce this and increase exhaust gas speed but the power increase from tape is marginal. The benefit needs to be weighed against the effect on the life of the manifold (outlined above) and the near certainty that if any part of the manifold is under tension, it will split.
( I would stick with paint
......................... and the factory manifold)

FWIW

Roger



RMW

To quote Jean Guy; ' Do not take ceramic coating or regular wrapping route as it retains too much heat and could be desastrous for the engine. Furthermore it is expensive for nothing'

Basically I replaced mine with a Pace Setter that I bought from Victoria-British. Cost was lower than other's, and seems like a good design. [What do I know]
I then had it blasted and ceramic coated, had a collector and 2" pipe alll the way back. Plus a rear chambered muffler, and a short center one as well.

The whole idea of ceramic coating is, it is now protected from rust, and as I have experienced, it cools rapidly. Cool enough to touch within minutes of shutdown. I believe it's coated on the inside as well.
Which gets the heat out quickly. Which increase HP.
I sure looks nice too.
Safety Fast
Dwight
Dwight McCullough

I've got the 2" Peco. Sounds great to me. It also wasn't difficult to install on my own. If you don't have a flowed head & a slightly hot cam, go for the 1-7/8" exhaust as the 2" won't do anything for you.

It was also stated that it will give you a little more hp (not much) over stock although your torque range will shift to a higher rpm.

Luigi
Luigi

thanks a lot to you guys and merry christmas !!
I will ask for an exhaust system to Santa ! I think i'll go for the peco one!
Alexia

Merry Christmas Alexia,

And a final word check that site:

http://www.studdsey.fsnet.co.uk/mgbtunings.htm

It could give you another point of view...


Cheers,

JGC @ 0F in Canada far from driving my B-GT
Jean Guy Catford

hi JG,

yer I already had this one, very interesting and as they say the peco one is not bad at all so ... stuck to my idea and am painting my exhaust mani curently
and don't think i'll put it on my own it's beyond my limits ...
cheers
Alexia

Hello,

A short question for JG Catford. What kind of hi heat paint do you use on your manifold ? And where do you buy it (in Qc City area maybe)?

Thanks

Happy holidays to all of you MG enthusiasts !!

p.s. MG = the car, not me !

MGaudreault

MGardreault,

it's a hi-paint special for exhaust spray written on the can, you have like 5 colours as choice and you can find it in any car shops!
cheers
Alexia

Hi MGaudreault,

An easy find, I suggest my favorite store, Canadian Tire, they have Tremclad hI-heat enamel, as far as I remember. You could find also in some hi-performance store like Brossard different brands.
Cheers,

JGC
Jean Guy Catford

Hello

In respond to JGC about hi-heat paint, Cdn Tire has one but they just have ceramic coating in manifold grey. As you mentionned above you don't recommend it. Does it apply to a standard manifold. Mine is a '78 with ZS carb.

Thank you

MGaudreault

Hi,


I'll check at CDN-tire and will come back lateer on...

JGC
Jean Guy Catford

This thread was discussed between 02/12/2004 and 22/12/2004

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