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MG MGA - Exhaust or Inlet manifold insulation?

I have been looking at various ways of keeping the heat from the exhaust manifold from affecting the induction system, I have a new Weber DCOE set up with Maniflow tubular exhaust manifold.

I had exhaust wrap on my previous tubular manifold/ SU set up but the manifold began to crack (apparently after becoming too hot) and I removed it, which appears to have prevented any further re occurence.

I have looked at getting the new manifold ceramic coated but I am not totally convinced that it can really be as good as advertised.

The new Weber inlet manifold is a simpler tubular design than the SU type and I wondered about fixing some insulating wrap around this instead of the exhaust.

I have fitted small Weber heat shield to the bottom of the carb.

I would appreciate any opinions on this.


Colyn Firth

I have the same set up as you, but the Webber sits on
a cast swan neck manifold. The Maniflow exhaust manifold and pipe are wrapped back to the middle of the front floorboard and have been for at least 5 years, without problem. I have had no heat/fuel issues since fitting the Webber but believe the DCO 45 is less susceptible to the problem than SUs.
D Townshend

We run a 1275 midget with tubular manifold and a 45DCOE, using super unleaded. We also have the small Weber heat shield. No wrap or coatings, and no problem with vaporisation. As an alternative view we ran a B with DCOE and tubular manifold but no heat shield and spent a lot of time waiting for everything to cool down once it was stopped for a short period - topping the tank up...
d brenchley


To answer your question about which side to wrap. From an engineering point of view surely it is better to wrap the exhaust as it is hotter and it is the source of the issue.

Paul Dean

I had my MGA exhaust manifold "jet coated".
It's resulted in a very obvious reduction in engine bay temperatures, and consequently also a very obvious reduction in heat conduction into the cabin.
It has also eliminated the slightly irregular running I used to experience for 30 seconds or so when restarting immediately after a hot run, which I always attributed to some fuel vaporisation in the carburettor bowls from the hot exhaust manifold below the heat shield.
You can now actually (lightly) put your finger on the exhaust manifold near the head after a run, and not burn your finger!
Theoretically the jet coating (or, if you prefer, wrapping) will also keep more heat in the head for more efficient combustion.
And I suspect jet coating (or wrapping) of your Maniflow manifold would also tone down some of the increased noise you'll experience from the resonance and less damping intrinsically afforded by a tubular exhaust manifold compared to the original cast iron exhaust manifold.
The coating (by a very reputable firm in the business in Sydney) only cost about $200; say about 100 pounds.

T Aczel


Following Tom's post I did a quick check and found this company at the home of the MGA. Might be worth an enquiry.

Steve Gyles

I asked for a quote last year from Zircotec and part of their reply was as follows:-

"The natural colour of our coating is white/cream, but many of our customers call for the very highest level of performance offered by Performance White™ but also require a coating with a finish that can be more easily maintained. To meet this need Zircotec has developed a range of high quality multi-coat colour finishes that are applied over the top of our standard plasma-sprayed ceramic. The full range of colours can be seen on the attached link ( ). Our Primary range is only available in a matt black finish.

Regarding pricing; for a MGA 4 cylinder cast iron manifold, the cost to coat is £136.00 for Primary Black™; £195.00 for Performance White™ or £223.00 for any from our Performance Colours™ range. Prices exclude shipping and VAT. Turnaround time is approximately 15 working days with payment accepted via credit card or bank transfer. "


m.j. moore

is this coating inside as well...?
Neil Ferguson

Thanks for the replies everyone,
Im not so keen on fitting an exhaust wrap
after my last tubular manifold cracked.
This is why I thought of wrapping the new Weber inlet manifold instead. It's the short swan neck design and it is easily accessible too.

I checked out Zircotec and it is an external coating only, JetHot coating doesn't seem to be available here in the uk but I have traced a company called Camcoat in the north of England who claim great things for their ceramic coating.

I value Toms comments as he has put such a lot of time into experimenting with the mgas cooling system.
I may well give the coating a try as at the very least, it could prevent the manifold from rusting.
I do though find it difficult to see how a thin ceramic coating can act as a thermal barrier but I will give it a try.

Thanks everyone
Colyn Firth

This thread was discussed between 19/03/2016 and 21/03/2016

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